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Thread: Misfire when cold, and high CO and lambda during inspection

  1. #26
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    Okay, I, very, very probaby found the cause. I tried to disconnect the vacuum hose from the fuel pressure regulator (which is located at the firewall and dificult to reach in between the manifold and the motor wiring above), and the hose crumbled in front of my eyes. The rubber was completely, completely deteriorated. So I disconnected the hose from the manifold (next to the CCV on a manifold port, but not connected to the CCV), and in the process the hose tore on several places.. It was really, really bad..

    So, that must have been the cause..

    So, the fuel pressure regulator wasn't able to regulate pressure down at higher manifold vacuums which only ocur at idle and very low loads (to ensure that the fuel pressure remains at a stable +3.5 above manifold pressure, which means +2.8 - +3.5 above atmospheric pressure).. And also, there must have been a vacuum leak.. Net result was the engine running rich at idle (due to too high 3.5 bar pressure instead of the expected 2.8 bar, with which the ECU was mapped/tuned) and running lean at higher loads (due to the vacuum leak).. Impossible for the ECU to adapt to properly..

    So, after changing the vacuum hose I should notice a strong improvement at idle and also some improvement at higher loads..
    I hope I can still drive to the car parts store (with the probably even bigger vacuum leak now the hose is completely removed) and replace the hose today.. It will be a bit tricky, reaching below the manifold (oh, it was so much easier with the M20 and M30 with the idle regulator, vacuum hoses etcetera *above* the manifold).. I'll probably have to remove the throttle body, MAF and air filter house.

    I'll let you know the results..
    Last edited by ed323i; 04-02-2018 at 07:09 AM.

  2. #27
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    Okay, changed the vacuum hose for a new one.. Was a pain in the ass to install. Both the nipple of the FPR, as the nipple on the manifold are virtually unreachable.. The BMW engineers should really have done a better job.. Or, even better, just should have left the fuel pressure at 3.5, leave out the vacuum hose and the nipple on the manifold, and just use a little less linear fuel map on the ECU (adapting to the increased relative pressure at idle and low loads).

    Here is a photo of the underside of the M52 manifold with all the connections:
    photo%20%286%29.jpg
    (taken from http://www.bimmerfest.com/forums/sho...d.php?t=751303 ).
    The nipple that goes to the FPR (#2 in picture; right next to the idle control valve hose, and on engine side) is really difficult to reach. I had to remove the oil filter housing lid, the CCV, the throttle body (to discover there was a plate blocking clear access) and it took me 2.5 hours to replace the hose.. On an M10/M20/M30 this would have been a 1 minute job.. If your arms are a bit wider than mine (mine are not so big), then you'd have to remove the entire intake manifold, just to replace a hose, that is gonna die every like 10 years.. What would have helped if I had bought the original BMW vacuum hose, which is made of very flexible rubber. The one I used is reinforced, and is like reinforced gas hose, so very stubborn to get on the nipple, and the inner dimension was, although identical to BMW specs, just too small due to the virtually zero flexibility, compared to a flexible rubber hose.
    #3 in picture was plugged with some rubber flexible plug, because in Europe we don't have the air pumps (luckily)..

    Anyway.. It's in now. Not sure yet about the results.. I've reset the adaptation values, and now I'll have to drive a bit more before I can check the new adaptation values.. Probably tomorrow evening, I'll know more.. If it hasn't helped, then perhaps, miraculously, the old rubber vacuum hose was still working, and changing the hose didn't change a thing.. Then I'll drive to a car mechanic to check the fuel pressure, to see if it's at +/- 2.8 at idle and at 3.5 with the throttle body butterfly opened up (no more vacuum). If that's all working fine, then the next suspect are the coils, which I'll then change all 6 of them for new ones I think.. Because at the moment they all seem to work okay, but it's difficult to say if they are working perfectly in all conditions..

    I'll let you know how it works out. Cheers Ed
    Last edited by ed323i; 05-20-2018 at 11:05 AM.

  3. #28
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    Alas, it's not fully solved yet.. Although there is definitely an improvement in how the engine handles itself, but this seems to diminish as the ECU is adapting more..

    INPA now reports this after some 80 kilometers or so:

    Bank 1: -16 aditiv and -6 multiplikativ
    Bank 2: -12 aditiv and -2 multiplikativ

    So, something has changed, but it's far from perfect.

    I'm afraid I used an improper hose, which is too dense, and it's still loosing some vacuum. I'm afraid I'll have to redo the procedure, and now install a proper flexible vacuum hose. I think I'll just buy the BMW original hose.

    At the same time, I'll be optimizing / simplifying the cooling hoses/tubing, eliminating quite some hoses and clamps that are not necessary in the climate here, making the system more reliable.. Check this thread: https://www.bimmerforums.com/forum/s...t-2-Is-this-OK
    Last edited by ed323i; 04-04-2018 at 03:30 PM.

  4. #29
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    Today I was looking below the manifold to see how much work it's gonna be to install the two silicone end caps on the engine head, once I receive all hoses and end caps in 1-2 weeks (details here: https://www.bimmerforums.com/forum/s...t-2-Is-this-OK ). I'm gonna be eliminating 6 hoses and 10 clamps to make the cooling system more reliable, eliminating throttle body heating and loosing cabin heater functionality (I can't remember when I used it in the last 2 years on the island here). I will also remove the heater valves, but I'll leave the heater core in the car (too much work to take out, and no real advantages except some slight weight reduction).

    I think with the M52 manifold and the E36 chassis, it should be possible to install the two end caps on the head without removing the intake manifold. Especially when I first remove all heater valve hoses and the heater valves themselves, I think I should be able to unscrew the hose clamp, remove the hose and install the end cap and a new hose clamp, reaching with my right hand below the manifold, from the firewall side. Also, because the M52 manifold is relatively open from above, I can see enough to make it happen. With the M50 or M54 manifold it's a lot more difficult I think.

    Anyway, back on-topic, I looked at the fuel pressure regulator and saw that the newly installed hose had already ruptured.. I think the inner diameter of the hose I bought was way too small (2mm), whereas the FPR nipple is 3.5mm I think.. I think it was already ruptured when I forced it on.. It just doesn't fit.. And it explains why it was such a tough job.. I thought BMW meant 1.8mm inner diameter and 3.5mm outer dimension when they specified 1,8x3,5, but it must mean something else.. I think a 3,0mm inner diameter hose should work though.

    Luckily I also ordered silicone vacuum hose of both 2mm and 3mm inner diameter. So when that arrives, and also a new CCV and hoses, I can replace virtually all rubber below the manifold.. And then I expect the engine to run as smoothly as BMW intended. Right now it clearly still has a vacuum leak. The leak itself will make the mixture a little bit leaner, but not so much. But more importantly the FPR will keep pressure at 3.5 bar also at idle and low loads, which results in an absolute pressure of 4.3 bar at idle (at idle manifold pressure is +/- -0.8 below atmospheric pressure), which causes the injectors to overshoot and make the mixture too rich.. Hence the high negative additiv values in the ECU fuel trim.

    I also had a brainwave, and instantly understood why vacuum leaks are way more important at idle and very low loads, than at higher loads.. At higher loads there is no vacuum in the manifold, and 99% of the air will just choose the path of least resistance, through the MAF and air filter. The tiny amounts that enter through the vacuum leaks have virtually no effect on the AFR, because of the high volume of air being sucked into the cylinders at higher loads.. Whereas at idle and low loads, the high vacuum will pull in the air from all vacuum leaks. Also, because a relatively low volume of air is sucked into the cylinders at idle, even very small amounts of extra unmetered air will change the air fuel ratio, and cause the engine to run too lean.

    So, hopefully in one or two weeks, when all stuff has arrived, my M52 purrs like a kitten at idle (and will not loose any coolant because of the three new hoses and the elimination of the other 6 hoses).

    Update:
    I get it.. When BMW specifies 1.8x3.5 they mean: 3.5mm inner dimension and 1.8mm wall thickness. I found that here: http://www.bimmerfest.com/forums/sho...d.php?t=574809 . I reckon the 3mm silicone hose will work okay then.. Better to use one a little bit too small than one that's too big (4mm is the next I could buy)..
    Last edited by ed323i; 04-06-2018 at 06:33 PM.

  5. #30
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    Still haven't received the silicone hoses.. I hope I'll receive them in a few days..
    In the mean time the M52 runs better and more fluent than before, even with the slightly torn vacuum hose.. No more cold start rough running..
    So I expect it to run perfectly once I install the new vacuum hose between the fuel pressure regulator and the manifold. I did receive the CCV and hoses, so I'll do everything at the same time, together with the coolant hose reduction.

  6. #31
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    Still haven't received the silicone hoses.. They are having trouble sending it from the UK to the Canary Islands (which are part of Spain/EU, but not part of the EU tax system, so you need export registrations to be able to send it here)..
    So, tomorrow I'll drive by the BMW dealer and buy the BMW 3.5mm inner diameter vacuum hose, which will probably also last 10 years..
    In the meantime, the adaptation figures had dropped to -45 .. So it's worse than before..

  7. #32
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    Yesterday I finally installed a 3mm silicone hose in between the fuel pressure regulator and the intake manifold.. And I think it's solved now. INPA now shows -4 and -2 adaptation figures for bank 1 and 2 after a 30 minute drive.. I'll check again after some time to see where the adaptation figures stabilize, but I'm quite certain it's fixed now. Before I had even seen values of -40 (perforated vacuum hose, so fuel pressure was always at 3.5 bar, and now lowered to 2.8 bar idle).

    To install the vacuum hose between the fuel pressure regulator and the manifold, what I did was:
    * Remove the air filter housing and mass air flow meter
    * Remove the ASC throttle body
    * Remove the throttle body
    * Remove the lid of the oil filter housing (store it in a clean place, and wrap it in a couple of layers of paper to prevent oil spills)
    * Cover the opened oil filter housing with a plastic bag
    * Disconnect the hose from the head (near the VANOS) that goes to the CCV. Press both lids and pull/wiggle it off.
    * Remove the three screws from the CCV valve and take the CCV out of its rubber in the manifold, and move it down as much as possible, so you gain space

    Now you should have enough space to get your arm below the intake manifold and install the hose to the intake manifold nipple. It takes some time to learn and feel where this nipple is located.
    Study this photo, so you know where to look for the nipple #2 (right next to the idle control valve hose, and on engine side):
    photo%20%286%29.jpg

    Once you've found it with your left hand, then bring your right hand to where throttle body was and try and find/touch your left hand finger with your right hand finger. Now you should be able to get the vacuum hose on, using both hands. It takes some perseverance but it's doable. Make sure you get a proper vacuum hose (original BMW is best, as it is 3.5mm and slides on the easiest) or silicone hose (3mm or 3.5mm). I advise against using a high pressure gasoline or diesel hose because those are too stiff and are very difficult to get on.

    On the fuel pressure regulator side it also takes a lot of perseverance. It's not easy to do, but with time you should be able to get it on. If you have big hands, you might need some assistance from your wife/girlfriend or someone with smaller hands/fingers.

    If you haven't changed the CCV valve and its hoses and rubbers, then it would be best to replace those too. Then you probably won't have to work below the intake manifold for several years.
    If you're in a moderate or warm climate, think about doing the throttle body coolant hose delete mod.. See my other thread for details. This gives a lot more space below the intake manifold and also above the power steering fluid reservoir, and makes the cooling system more reliable (less hoses, less clamps). And it also allows you to add a third temperature sensor (M12x1.5) in the head, which you can use to drive a temperature gauge, which shows exact temperatures instead of buffered temperatures like the factory gauge does.
    Last edited by ed323i; 05-20-2018 at 11:10 AM.

  8. #33
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    After driving around for 5 days, not too many kilometers, the additive adaptation values are now at -15 for both banks.. So definitely better than it was.. Adaptionswert multiplikativ is at +2 for bank 1 and +6 for bank 2. Not sure if the -15 additiv values are considered as 'in normal range' of if they are a bit low.. To complicate matters, I use a tuned DME with a general M52B25 tune (should give 190 crank HP and 260Nm, but not specifically tuned for my engine; but it seems a proper tune so it should have okay values in the fuel map at idle rpm/loads).. Let's see. I think, if the adaptation values stay in the ballpark of -15, I leave it be.. At -45 it was obvious something was wrong.. The car runs great and has great throttle response (improved a lot with DME tune, but also improved a little due to fan delete mod, which I like a lot). When I drive in it, it always gives me a big grin, and I think a stock E36 328ia will be no match, acceleration-wise due to torque convertor losses. And I think a stock (not-tuned) manual 328i might be just a little faster, but only if it's in good shape with working Vanos, high cylinder compression, etc.

    Screenshot INPA (engine off):
    capture_inpa_001_25052018_144042.png
    I think that with the M52 (non-TU), INPA reports the additiv as 1 hundreds of a milisecond, and multiplikativ as percentage values; idle injection time is probably something like 2.0ms, so additiv -15 will turn it into 1.85ms, which means +/- -7.5%. With the M52TU the additiv is reported as miliseconds, so there it would show -0.15 I think.

    P.S. Let's first see if that values stabilize at +/- -15. If they continue to drop lower, then I'll have to change the fuel pressure regulator. Perhaps do some pressure tests before, with a running engine, to confirm that fuel pressure drops when manifold pressure is high (keeping relative pressure between manifold and fuel at a stable 3.5, which means dropping absolute atmospheric reference pressure to +/- 2.8 at idle).

    Update:
    Hmm.. I still have some work to do.. -15 won't do.. If the aditiv value is lower than -2 [later updated: should be -20], then there must be a problem, according to this chart: https://www.motor-talk.de/bilder/ada...207551845.html . Perhaps the manifold nipple is blocked and is not passing vacuum to the vacuum hose and fuel pressure regulator. Or the fuel pressure regulator membrane is bad. Because the engine, at higher loads (the multiplikativ value of +2% and +6%) runs slightly lean, but within range (at > +8% there is a problem, according to same chart), and at the same time runs rich at idle, it must be the fuel pressure regulator not adjusting to intake manifold vacuum.. I'll try and find a fuel pressure tester and see what pressure the FPR adjusts to at idle and low loads..

    Another update:
    According to circulating 'BMW Fuel Trim.pdf' file (of which I'm not 100% certain if it's correct), an aditiv value larger than 112% of +/- 0.35ms (with M52/MS41 this would be 39) for longer than 10 seconds will trigger an error code. So, with an M52TU/MS42, the DME would be perfectly happy with the -0.15ms. No problem whatsoever. Adaptation within normal range.. I'll do some more reading on the topic, and if I can find a cheap fuel pressure meter (or a garage that can do it for me), I'll do it to make sure the FPR adjusts for the manifold pressure..

    And yet another update [everything seems fine; -15 additiv is in range after all : When I wrote "I still have some work to do.. -15 won't do" at the first update, I was incorrect.. The linked charts says 0.2ms, which means 20/100ms.. That means that anything between -20 and +20 is 'in range' according to BMW.. So, -15 seems to be okay according to both the linked chart (up to -20 = 0.20ms) and the BMW Fuel trim pdf (up to -39 before error is stored; which by the way with the M52 never gets stored it seems)..

    So what I'll do is I'll keep on driving a bit more and see if it stabilizes in the -20 to 0 range.. If it does, then it's in range and everything is fine. If it doesn't, I'll be checking the fuel pressure at idle (should be 2.8 bar)..
    Last edited by ed323i; 05-25-2018 at 08:55 PM.

  9. #34
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    Today, I started the car with cold engine, and it wasn't running on 6 cylinders and smelled really rich from the exhaust.. So, problem NOT solved yet..
    I'll measure the fuel pressure with the engine running and see if it compensates for the high intake manifold vacuum while idling, lowering fuel pressure from 3.5 to 2.8 bar. If it doesn't, then I'll replace the fuel pressure regulator.. If that doesn't solve it, then perhaps the little intake manifold pipe, to which the vacuum hose is connected might be clogged/plugged and no vacuum makes it to the FPR?

    I hope I can solve it soon.. I think the running rich shows the most symptoms when the engine is cold and the DME enriches the mixture even more (and has no oxygen sensor feedback in open loop mode), up to the point that the mixture gets so rich that it causes misfires.

  10. #35
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    Today I connected the INPA laptop and the additive adaptive values were -13 and -10.. So I consider the problem solved.. The vacuum hose between fuel pressure regulator and intake manifold was ruptured, and this caused the fuel pressure to stay too high during idle, causing very high negative additive adaptive values of -30 to -50. Once I replaced the vacuum hose, values dropped to -13,-10 range, which is in normal range (up to -20 is OK according to BMW).. So: problem solved.

    When cold it still tends to misfire a little, so I'll be buying a new coil and will try and find out which cylinder is the culprit.
    Also, if I'm in bad luck, perhaps the catalytic convertors aren't that great anymore and that's what causes the rich smell at the exhaust.. I bought the used 328i exhaust front-to-back, and didn't know the mileage. After installing it, it passed the inspection perfectly fine, but second year it passed it only after heating up the catalytic convertors a lot.. So next year (in January) I need some luck.. Best to find a spot and time where I can drive the car into the inspection directly after warming up the engine/cat very well.. Last time I had to wait over an hour before they helped me, which must have lowered the cat temps too much.
    Last edited by ed323i; 06-23-2018 at 08:32 PM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  11. #36
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    I have INPA running properly now, using a new FTDI232 USB OBD2 cable instead of the CH340 USB OBD2 cable which caused many, many connection errors. I can now finally check all live values with the engine on.

    Interestingly, after resetting the adaptation values with the engine running, the DME very quickly learns the new adaptation values of +/- -30 additive for each bank. It took less than 10 minutes for it to relearn the new additive adaptation values. I think it goes this fast, because the engine was idling all this time, so the DME could learn from a very static situation; same load, same rpm all these 10 minutes.

    I did some math to see if the -30 value (-0.30ms injection time) seems correct if indeed the bad FPR (which will be replaced next Tuesday) is the cause..

    So, here are some specs:
    3.5 bar normal fuel pressure (Bosch/BMW specs)
    M50 and S50 seem to pull -20 or -21 in/hg vacuum at idle
    -21 in/hg equals -0.7 bar

    So the DME expects a fixed 3.5 bar at idle, but in reality it gets 4.2 bar (because the FPR doesn't compensate for the 0.7 bar of vacuum, the relative pressure is 3.5 - -0.7 = 4.2 bar)
    So, pressure at 4.2 is 20% higher than what the DME expects (4.2 / 3.5 = 1.20 = 20%)
    Using flow/pressure calculator, the flow increase is 10% (so, for each ms the injectors are open 10% more gasoline flows through them)

    I don't know what's the normal injection time at idle for the M52B25, but it should be somewhere between 2.0 and 3.0 ms I think.
    At 2.0ms normal injection time at 700rpm idle, throttle butterfly valve closed, the DME should reduce injection time to 1.82ms (2/1.10), which equals -18 additive adaptation
    At 3.0ms normal injection time at 700rpm idle, throttle butterfly valve closed, the DME should reduce injection time to 2.72ms, (3/1.10) which equals -28 additive adaptation

    So, if indeed injection time at idle equals 3.0ms with the M52B25, then the adaptation values of +/- -30 seem correct.

    I'll do some more tests once the FPR is replaced, probably next Wednesday. I'll let you know the results. I hope the additive adaption values will move to the healthy -5 to +5 range.
    Last edited by ed323i; 08-29-2018 at 01:21 PM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  12. #37
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    Okay, car is at the garage now.. Will be a big transformation as I've also asked them install Bilstein shocks, Meyle HD control arms, stabilizers, etc.
    When they told me that cleaning the injectors (ultrasonic) would be only 30 euro more (they already have to remove the injector rail because of the FPR), I gave them the go ahead..
    So, with some luck, the M52B25 will run like (virtually) new after the job's done..

    Will let you know the results.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  13. #38
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    They're still working on it.. The garage had a backlog of about 6 BMWs, and the garage owner also called me to tell me they had some trouble replacing the outer steering joints I think because of corrosion/being stuck.. So that added to the delay. Hopefully will all be ready tomorrow afternoon.. I can't wait to feel how the car and the engine feel/run after they're finished. I also watched some youtube videos on installing the E34 steering u-joint instead of the 21 year old rubber one currently in.. Seems tempting, and a very simple upgrade.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  14. #39
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    Damn... I hope the garage I took the E36 to has done its job to perfection, and the invoice he will show me, shows some very, very low prices. Otherwise I won't come back ever.

    I left the car with him Monday evening at 8PM, and he would start work Tuesday morning at 8AM.. Car would be ready be Wednesday the latest, or even Tuesday evening.
    Four days later, and I still haven't got my E36 back, and I learnt (too late) he closed early today at 3PM.. No phone call, no message from him what so ever, all those days. And he's closed for the weekend.
    So now I'm without car for almost a full week.. And we have no car to take our daughter to school Monday morning. Will probably have to call a cab (luckily not very expensive) Monday morning.

    What I'm really pissed about is that he didn't communicate anything. I always had to call him and then he would say we need another day. Etc, etc. One day he didn't answer the phone at all, and I just had to guess it would take another day. All in all, all the work should be possible in 4-5 hours max.. So, in all those days he didn't find those 4-5 hours (probably gave priority to other customers, who were behind me in the queue)..

    As the garage is on a public road, and the E36 parked in front of the garage, I was able to inspect his work this evening, and luckily the 4 Bilstein shocks are in, as are the front discs and pads. I assume the Meyle HD control arms and bushing are too, and also the steering outer joints. Don't know if he changed the diff, manual gearbox and engine oil. He probably did install the new fuel pressure regulator. This morning (on the 4th day) he decided to sent off the 6 injectors, without asking me what I would prefer, and without asking if I would need the car this weekend and Monday morning..
    So, the injectors didn't come back in time today, and he didn't let me know anything, and I'm without car. Of course it's boxed in by other cars, so even if I would take the spare key, and get myself another set of injectors, I wouldn't be able to get the car out..

    Sorry about the rant.. But I was really pissed off.
    Alas, that's one of the disadvantages of living in Spain. Lots of Spanish people never really got a grip on capitalism and the resulting competitiveness and client friendliness..
    The strange thing is he gets away with it, as he's booked full 5-7 days in advance. So I hope he did a really great job and will ask a very low price. We'll see on Monday (I hope he'll have the car ready by then).

    P.S. Luckily there are also lots of very positive aspects of living in Spain :-) ..

    P.P.S. Yes, we've been driving this E36 for 2.5 years now and it never failed us (hasn't been flawless though, but would always start and drive).. With some luck and some preventive maintenance the E36 can be a great daily and only drive, just like the E30 we had before.. Here on the island you can't do anything without a car, or you must fancy walking or bicycling on roads with up to +15 or in some extreme cases even +20% inclination/grade. The volcanic island goes from sea level to over 3718 meters (top of the volcano) altitude in just a few kilometers (13 to +/- 25km depending on which side of the island you start) from the coast.
    Last edited by ed323i; 09-07-2018 at 10:14 PM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  15. #40
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    The shop/garage owner WhatsApp'ed me today, and wrote that he picked up the cleaned injectors today, on his free day.. So that's a nice gesture.
    He also wrote the injectors were in really bad/dirty shape, and it took 2 days of ultrasonic cleaning to get them in shape.. Monday at 1 PM he'll have the car ready.. So, that's good news.

    So the 'misfire when cold' was probably caused by a clogged injector with very poor spray pattern.. Perhaps a little worsened by the FPR, as the adaptation values in the DME can't cope with a too wide range of loads (every load is affected differently by the malfunctioning FPR as the vacuum decreases with load), and after a cold start the oxygen sensors aren't working yet..

    Chances are the E36 will run a lot better than before.. The way an M52 should run, silky smooth (which it definitely didn't, even though it has 6 new coils, and great, almost identical compression values in all 6 cylinders).

    The injectors were probably that bad because the car hadn't been driven for 2 years, burning in the Spanish sun, when I bought it in January 2016.
    Last edited by ed323i; 09-08-2018 at 04:34 PM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  16. #41
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    Eventually I got the car yesterday (Monday) evening at 7PM. Job well done. And he only asked 120 euro for all the work (Meyle HD control arms + rubbers, 4 new shocks + extra parts, 2 new outer steering joints, fuel pressure regulators, removing and reinstalling injectors, 2 stabilizers, 2 front break discs and pads, replacing 2 fuel hoses next to fuel filter, replacing the 4 door handle gaskets).. I think that's a very good price.

    Then he also had the wheels re-aligned for only 25 euro. He also changed engine oil & oil filter (56 euro) , diff oil (22.50) and manual transmission oil (20.00). He supplied the oil.
    I supplied all parts, so there were no costs for the parts. I did forget to include the rear shocks plastic dust covers and there he charged me the OEM price I'm afraid (40.50 euro).
    And cleaning the injectors was a bit expensive, at 80 euro.. But he told me his technician had also flow-tested them until they were all equal. And they needed a lot of cleaning.

    So all in all, I'm happy. Communication was very poor, but eventually he made up for that with his very low labor price. Next time, I'll only let him do small jobs at a time and I will ask him to guarantee that he starts the job when I arrive. Then I just stick around until the job's done.

    With the Bilstein B4's and the complete suspension overhaul, the car feels quite different. A major improvement. It gives a lot more confidence in the corners now if you're trying to find the limits. And the limits have moved a lot. The B4's are stiffer than I thought, so a great upgrade.

    So, that part all happy!

    But, "mierda" (shit in Spanish).. The additive adaptation values still move to double digit (or even 20-30) in the negative range...
    I'm out of options now.. So I said, Mierda, I'll just reset the adaptation values and disconnect both O2 sensors and be done with it.
    Effectively the car is now like a European 1986 E30 325i, with a nice Motronic DME, but without any adaptation or O2 sensors. And those who drove that car know it drove very well.

    It definitely runs best with the adaptation values at zero.. So, I have no clue what else to look at..
    Both banks have identical adaptations and the O2 sensors give comparable values (after viewing live INPA for quite some time).. So chances of it being the O2 sensors are slim.. On the other hand I have no idea how old they are, and perhaps they 21 years old.. So perhaps they developed the same bias.. Alas, they are hard to find for a reasonable price.. Paying 200 euro and then discovering that also wasn't the cause would be a PITA..

    Well, if anyone has suggestions, please let me know.. But for now, I'm just gonna enjoy the new ride.. And it also runs better with the injectors cleaned. But I think it's safe to conclude the fuel pressure regulator wasn't faulty.. Oh, wait, I'll ask the garage/mechanic to do a fuel pressure test at idle.. Their hour rate is so low it's worth the hassle. Just to exclude the posibility that the vacuum nipple on the manifold isn't blocked some how (in which case the FPR would get no vacuum and wouldn't be able to adjust pressure, even though the FPR is new and the vacuum hose is new)..

    Summary: Additive adaptation values slowly but steadily move to -30 (minus 30) or even lower, both banks, while multiplicative values remain near 0%
    * New fuel pressure vacuum hose (no change)
    * New Fuel pressure regulator (no change)
    * Six new coils (no change)
    * Six injectors cleaned and flow-matched (no change)
    * All intake vacuum hoses and boots checked, and replaced where needed (no change) (also, vacuum leaks should give positive adaptation values)
    * CCV replaced and all hoses (no change) (also, vacuum leaks should give positive adaptation values)
    * Compression checked: All 6 cylinders at 11.0 bar +/- 0.2 bar (so perfect, almost like new)
    * Other DME (it now runs a chip tuned DME instead of stock) (no change)
    * It runs an original Siemens MAF (before I had a junk Ebay one)
    * All live INPA values checked. All temp sensors give OK, plausible values
    * It seems to have most power and smoothness with adaptation values reset at zero

    The two main possible causes for negative adaptation values are too high fuel pressure, and severe misfiring. Other options: bad oxygen sensors, bad MAF, bad coolant temp sensor (which send too low temps to DME, which then over-fuels because it thinks the engine is still in warm-up cycle)..

    Update: Am gonna recheck the MAF.. It's an original Siemens MAF, but it's a used one.. It was a major improvement over the very bad ebay MAF (DO NEVER BUY THESE), but I have no way to tell it's 100% OK.. I'll be comparing live INPA MAF values I can find on Youtube M52 videos with my live values.. See if there's a difference. If my MAF over-estimates the amount/mass of air being sucked into the engine, then the DME has no option than to inject less fuel to obtain a good AFR..
    Last edited by ed323i; 09-11-2018 at 06:42 PM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  17. #42
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    Similar issue for me here’s how to test MAF function.
    Turn key to on and go into INPA reset your adaptations. Turn key off unplug maf start car. The car will now run in its default setttings and fuel car based on throttle position l(hope that sensor is bueno). How’s the car feel? If it runs worse it’s not your MAF if it runs better or even slightly better replace MAF with reliable unit.

    Also a bad MAF Will show in INPA by a large negative additive, similar to bad fpr, and a positive multiplicative number. And that’s a general indication could still be other things but run that test
    Last edited by ArcticM; 09-13-2018 at 08:43 PM.

  18. #43
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    Thanks for your suggestions..

    I've just used INPA to measure the MAF flow.. And at 700rpm idle, it's very stable at 11.50 - 11.75 kg/h, which is exactly identical to the values I found in this Youtube video (idle at 3:16 - 3:30):


    So, I think I can safely conclude the MAF is working fine, at least at idle.

    It runs very well now with the oxygen sensors disconnected.. But it smells rich at idle.
    I'll ask the mechanic to do a fuel pressure test at idle.. I still have a feeling that pressure is too high (3.5 bar instead of vacuum corrected 2.8 bar)..
    If, somehow pressure remains high at idle, the pre-programmed AFR of 14.7 will drop to 13.2 (no oxygen sensors connected, so MAF can't adjust), which is too rich, and the catalytic convertor won't be amused, but it won't cause the spark plugs to foul I think. I already have doubts about the health of the catalytic converters, so I'm not risking that much. But I'll ask for the fuel pressure test, just to exclude that possibility..

    Here are some other reference values for the MAF flow:
    M52B20, 10.5 - 10.75 kg/h, https://www.youtube.com/watch?v=nTEnQEUQlb8

    Interestingly, it's a very small difference between the 2.0 and 2.5 . The 2.5 takes just slightly more air, and hence fuel at idle. (+/- 10-12% more, while it has 25% more cc)..

    Update: Here's an M52B28 and it only uses 10.5 kg/h .. Less than what my M52B25 uses (11.5-11.75).. So, that's odd to say the least.


    Or is it corrected for air temperature? It's quite hot here today (28 degrees C) and air temperature was at 62 degrees C, INPA indicated)..
    Other values: rpm +/- 700, air temp 61.7C, coolant temp (aux fan just turned off) 88.6 deg C, TPS at 0.6V, Last/Load 92.13 mg/stroke.

    Thought: Perhaps this M52B28 has a vacuum leak and that's why it's registering so low.. The other M52B28 videos I found are near 13-14 kg/h, but they often had an idle rpm of 750 rpm (so, perhaps A/C on or alternator on high load?).

    Request: If you happen to be using INPA in the next days, could you please write down the MAF flow (kg/h) at 700 rpm idle (A/C off)? It can be found at Analog Values 1.
    I'd like to collect some reference values..
    Last edited by ed323i; 09-14-2018 at 08:45 AM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  19. #44
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    1997 BMW E36 323i
    Quote Originally Posted by ArcticM View Post
    Similar issue for me here’s how to test MAF function.
    Turn key to on and go into INPA reset your adaptations. Turn key off unplug maf start car. The car will now run in its default setttings and fuel car based on throttle position l(hope that sensor is bueno). How’s the car feel?
    Sorry, forgot to mention that I've done that test several times in the past. With the cheap Chinese ebay MAF, the difference between MAF-installed and MAF-disconnected was really big.. Going from very sluggish and low-torque/HP to very fluent and high HP.. Tip: Do never buy any other MAF than VDO/Siemens (OBD2) or Bosch (OBD1).. The clones are really, really bad. Your car will run lean and then rich and then lean again. They are just very poorly calibrated. Total waste of money and I've tried 3 of them.. All performed very poorly (but will get you home if you have no alternative, and disconnecting the MAF doesn't work)

    Once I installed the Siemens MAF it drove at least as good as with MAF not installed.

    Right now, with the tuned DME, it runs better with the MAF than without the MAF, as the DME has improved fuel and ignition values when running with MAF, but not without MAF (Alpha-n).. Most tuners don't bother to also retune the Alpha-N mode of the DME.. And I've even read that they don't even know where the Alpha-N tables are located in the DME's ROM.

    After running with MAF and O2-sensors installed, the adaptation values go very negative and then I lose torque and power and it runs less fluent.
    But with MAF installed and without O2 sensors, it runs perfectly fine. High torque and HP and very fluent, also at cold starts.

    Most logical explanation would still be a too high fuel pressure at idle and low loads.. At high loads it seems to work just fine as the multiplicative adaptation values remain near 0.
    I double checked if the mechanic really installed the new FPR by inspecting the old one, and it definitely is the old one he gave me after the job (stains, etc, which show its age).

    Fuel pressure test is what I'll do now.
    Last edited by ed323i; 09-14-2018 at 01:58 PM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  20. #45
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    After driving around for about a week now without the oxygen sensors attached, I must say it drives very well. No hesitance, no bad cold starts. Idles more smoothly.
    I think it's still slightly off, running probably slightly rich (10% too rich at idle, up to 0% at WOT if it's the FPR not getting vacuum), because it feels a bit less aggressive/powerful down below than before, on the days when it would run great.

    Still haven't done the fuel pressure test, but I think I will install a Bosch wideband oxygen sensor I have lying around (LSU 4.9, also M18x1.5 so easy fit). Will just have to find a cheap wideband controller, probably the 'SLC Free 2' from 14point7. Then, along with the Test-o software, I'll be able to measure what the DME is exactly doing (with oxygen sensors connected), and compare it to the wideband o2 logs. I'll know very soon if the BMW oxygen sensors are wasted, or if the fuel pressure is off. I can also run without the stock O2 sensors, and see what AFRs I see. If the FPR isn't doing its job (not adjusting to intake manifold vacuum), I would see rich idle, rich low loads, slightly rich medium loads, and OK high loads (WOT).
    If the stock oxygen sensors are wasted, I can use the simulated narrowband o2 output from the wideband controller to fee the DME, and then it should all run fine again.

    As a bonus, I can fine tune the already tuned DME.. Find lean or rich spots and adjust the map using romraider (haven't used it yet)..
    Last edited by ed323i; 09-23-2018 at 08:29 PM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  21. #46
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    I've been thinking a bit.. Perhaps I'll just buy:
    1x SLC Free 2 without LSU 4.9 O2 sensor (because I already own the sensor) ($45)
    1x SLC Free 2 with LSU 4.9 O2 sensor included ($95)

    And then replace the old oxygen sensors with these, and install two AFR digital displays (included with the SLC Free 2 kit) in the cabin, and feed the narrow-band output from the controller to the DME.

    Per sensor, it's cheaper than the OEM NGK oxygen sensors, so, to me it's a no brainer.. Will need to install some wires and do some soldering though.. But would be a cool, dual bank O2 wideband sensors, including O2 sensor temperature display.

    Then I can completely fine-tune the pre-tuned DME and perhaps get a little more HP out of the engine. I really liked tuning the Megasquirt 2 installation in my ex E28 528i. It will be a bit more difficult though, as the Siemens MS41 doesn't accept wide-band input, and the MS2 did, so it was able to 'autotune' the pre-specified AFR's.

    I'll think it over and let you know if I go ahead..

    P.S. Narrow-band oxygen sensor, like the stock NGK sensors, are quite "dumb" and only show "rich" (<14.7) or "lean" (>14.7), nothing in between.
    Wide-band oxygen sensors, like the Bosch LSU 4.2 or LSU 4.9, show (when connected to the special controller) "AFR is exactly 14.7" (or any other value, very high precision). In reality it says "lambda is 1.00", but you can convert this to AFR by multiplying with 14.7 for gasoline.

    So, if you want to tune your engine yourself you really need a wideband O2 sensor, especially at WOT at higher RPM, because you won't like it if your narrow-band tells you "rich" while in fact it's only AFR 14.6, but you need AFR 12.5 or AFR 13. Wideband will tell you exactly what's going on.

    Update: Damn, Because the MS41 (M52 DME) uses Titania O2 sensors, there currently is no wideband controller that can feed the DME the proper signal/voltages it needs.. At least, that's what I read here:
    "There is no current way to use a wideband to replace a narrowband on ms41" .. That's a bummer.. I'll be looking for some more info to see if somebody came up with a solution in the meantime, but it doesn't look good..

    So, that means, if I would install two widebands, I would also need to install the 2 narrowbands to provide the MS41 DME a good O2 signal.. Very expensive... And I would need to add two bungs to the exhaust manifold or exhaust pipe (pre-CAT).

    Update 2: Yay! It seems to be possible after all.. At least, by setting it up like this:
    "
    It seems to work for me. I have it set to output 0.6v at 14.55:1 and 4.7v for 14.65:1" .. At least with the LC-2 controller.. But should probably also work with the SLC Free 2.
    Last edited by ed323i; 09-24-2018 at 08:32 PM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  22. #47
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    1997 BMW E36 323i
    I just remembered something. As I installed a European OBD1 328i exhaust in my "OBD2" (in Europe it's not really OBD2, but it sort of is) 323i, the exhaust has one oxygen sensor bung in a cross-section before the cats, which the exhaust mechanic plugged with a bolt when I let him install the exhaust..

    So, I can remove that bolt and install the LSU 4.9, and get the 14point7 SLC Free 2 for $45, and after some wiring, have a functioning AFR readout in the cabin.. Then I can double check if the oxygen sensors are really doing their job.. If not, I'll just have to bite the apple and buy the 2 narrowband sensors, and accept that they're more expensive than the wideband sensor+controller kit price. I don't feel comfortable running the wideband's narrowband simulation output to the DME, because of the few bad reviews, and also because the Titania oxygen sensor is a bit of an odd-ball w.r.t narrow band oxygen sensors (0-1V range and other different characteristics compared to the more regular 0-5V sensors)..

    So, will let you know how it goes.. Will probably be some weeks until I get the controller.

    P.S. Car runs just fine with the O2 sensors.. Rock-solid, no hesitations, perfect.. But I think the DME might have retarded the ignition timing a bit, because it doesn't "dare" to go all the way without the O2 sensors.. I also read somewhere the MS41 DME might disable the knock sensors. It just feels a bit less snappy than before. Perhaps I'll join the MS41 romraider forum to see what details they have for me.
    Last edited by ed323i; 09-27-2018 at 06:31 PM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  23. #48
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    Holy shit..

    I just joined the Romraider forum and I almost immediately found this:
    http://www.romraider.com/forum/viewt...p?f=58&t=14941 (check first and last post)

    Very shocking.. INPA doesn't report the additive adaptation values as 1/100s of miliseconds, which I assumed..
    It's a PERCENTAGE of the maximum allowed deviation, which, for the M52B28 (not sure what it is for the M52B25), equals + or - 0.38 ms (at idle).

    So, in my case, it shows, say -30%, which then equates to -30% of 0.38ms = 0.114 ms..
    Assuming that a normal injection time at idle is +/- 2.0ms, the adaptation turns it into 1.89ms, which is only a deviation of 5.7% .. Not something to really worry about I think.
    If the FPR really wasn't compensating it should be adding 10% excess fuel at idle (high vacuum, so relative vacuum turns to 3.5 + 0.7 = 4.3 bar, which adds causes about 10% more fuel flow)..

    But I still think the engine runs worse with the oxygen sensors connected. So somehow it gets leaned out too much.. I'll do some more tests soon.

    Summary: What I thought was -0.30ms adaptation, in reality is only -0.11ms adaptation. Almost one third of it..
    So, another conclusion. The DME will only start complaining if the additive adaptation reaches - or + 100, which equals 100% of 0.38ms = 0.38 ms..

    This seemingly is a problem of the MS41-INPA combination.. Using RomRaider logger you get the real values.. And the MS42 and MS43 don't have this problem and show correct INPA values..

    Update: So, say the additive adaptation values remain at +/- -30, which equals to -0.11ms, then with the oxygen sensors disconnected and adaptation values reset, the engine will run at AFR 5.7% richer than normal, so instead of 14.7 it would be 13.9, which is a bit rich.. Or, the oxygen sensor aren't accurate anymore and it's now, with oxygen sensors disconnected, at 14.7 AFR and with the oxygen sensors enabled, it would run too lean, at 15.6 (as 15.6 * 0.943 = 14.7) ..

    Only new OEM O2 sensors will show me what's really happening (with a big risk that the oxygen sensors didn't need replacing, and I'm +/- 200 euro poorer). Or the wideband sensor, which will tell at exactly which AFR the engine is running with and without O2 sensors connected. Will be an interesting experiment..

    Another option is to only buy one new narrowband OEM oxygen sensor, plug it in the cross-section bung of the exhaust (before the cat), and use romraider to order the ms41 to only use that single O2 sensor instead of the two.. Makes logging and tuning a lot easier, they say in the forum.

    I'll start by doing some more tests, with the oxygen sensors enabled, and see if it really runs worse with the sensors connected. I can also test with just one sensor connected, hoping the DME will interpolate between banks (copy adaptation values for bank 1 to bank 2).
    Last edited by ed323i; 09-27-2018 at 08:43 PM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  24. #49
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    Very interesting update:
    Today I reconnected the 2 oxygen sensors.. And, wow, what a difference. It seems that if you disconnect the O2 sensors, not only are the knock sensors disabled (which is a fact, confirmed by the romraider guys), but also, quite logically in hindsight, the timing is retarded quite a few degrees. With the oxygen sensors reconnected, and the timing no longer retarded, the car feels alive again.. Before it felt OK and relatively quick, but now it really responds aggressively to the gas pedal. Especially noticeable on the low revs..

    Another theory is that the DME reverts to a completely different table with oxygen sensors disconnected, and perhaps my tuner didn't tune that table, so I was back at square one, the non-tuned (actually very down-tuned at factory) 170 HP OEM tune..

    Anyway.. The way it accelerates from say 1200 or 1500 rpm has changed considerably. A lot more fun driving the car again. Out here in Spain, I feel like 'the King' ;-) again on the road. Not many modern BMWs or Mercedes's driving around here. So, not much to worry about.

    So, now to see if the hesitation returns, or if that was only caused by the filthy injectors. I'll keep you updated.
    The 5% injection time cut (additive adaptation values of 30 in INPA, which mean 30% of 0.38ms, which is nothing) don't worry me anymore, and could be due to slightly de-calibrated MAF, or, whatever. It's such a small deviation, that I will just ignore it.

    Fingers crossed that tomorrow at the cold start it runs fine and doesn't hesitate. There is one nasty stop sign at a quite steep hill that we drive by each and every day with a cold engine, and it's not handy at all if the engine stumbles when you release the clutch pedal.
    Last edited by ed323i; 09-30-2018 at 02:26 PM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

  25. #50
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    So far so good. No hesitation, no stumbles, when cold.. Haven't connected INPA yet, so don't know how far the additive adaptation has adjusted already.
    Lots and lots more power, especially at low revs. Taking roundabouts in 2nd gear, it once again feels like it wants to drift, on a dry road.. Big smile :-) . Before it was a good, relatively fast car, but a bit lame. Now it wakes up the Dr. Hyde inside of you :-) .

    I think the DME turns into some sort of limp/safe mode when both O2 sensors are disconnected. And it's definitely more than 2-3 degrees that it retards the ignition timing.. It's a lot..
    Last edited by ed323i; 10-01-2018 at 06:31 PM.


    1997 E36 BMW 323i
    (European) 275k km (171k miles), with following small mods:

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