Another crank no start issue

[ed323i]

I personally can't see how a vacuum leak can cause the engine to run that rich (8.5 AFR is very, very rich, almost twice the amount of fuel).. Normally a vacuum leak will cause an engine to run too lean, as more air is sucked into the engine than the MAF and DME are aware of. (but perhaps, in a turbo setting other things can happen, not sure, no experience with turbo's; I'd assume that at idle the turbo is not spooling and there is normal vacuum in the intake manifold, so the same rules apply like with N/A engines)...

I think you can assume that the ignition is running fine (coils, DME, crankshaft and camshaft position sensor), and something is going wrong with some sensors, causing the DME to think it needs to inject way more than what's really needed.

Can you reset the DME, so that all fuel trims are reset? And then just try and run without O2 sensor. If the O2 sensor is the cause, then you'll see normal AFR's.
What else can cause this, as you've already replaced FPR? The MAF sensor, or a shorted DME.. (or perhaps something gone wrong while burning the EPROM that's used to tune your DME; they selected the wrong image perhaps? but probably not, as it ran fine before; I assume it's a custom tune, taking into account the very high cap. injectors and the MAF used).

If you know someone in the area with the same MAF, perhaps you can ask to use his MAF, to exclude that possibility.. Did you buy a new one, or is it a used MAF?

[DSGBUILT]

it was all bought new .
i also made a home made smoke tester and after pumping the system found a leak at the brake booster /manifold hose where i used to route the vacumm for the bov valve.
tighten it air tight and tried to start the car but still no luck but did notice that while cranking it feels alot more healthier and like it wants to start, also noticed that while cranking her up the afrs were alot higher, still not good but higher, 10.7 to be exact and thats on a super cold engine.
it got cold in the garage and my flashlight died so i couldnt check for more leaks so i called it quits(had a long day shopping with the gf and kids)
come tomorrow im going to check if i c anymore leaks and go from there.

this is my race car and i only use it to go to drift events in the summer time so i got some time to sort it out, as long as i figure it out by summer time ill be happy.

ill keep everyone updated

[ed323i]

Bad MAF or bad O2 sensor or bad tune are the most probable causes, I think.. Since MAF is new, that's probably not it.

I see no way how vacuum leaks can cause a too rich mixture.

You could also install an adjustable FPR and set it to a very low pressure, such that it will compensate for the excess fuel. But that's no real solution.

[s13flyboy]

This might be a silly suggestion, but are you sure the tune is installed? If it wasn’t then you’ve got huge amounts of fuel from the larger injectors that the DME doesn’t know about and it probably would run as rich as you are seeing.

I haven’t put a tune on mine yet, but I’ve read about similar issues from others on the forums. Give Zack a shout he’s a good guy and very helpful.

[DSGBUILT]

Ye the chip is in the dme

[vollosso]

Bad MAF or bad O2 sensor or bad tune are the most probable causes, I think.. Since MAF is new, that's probably not it.

I see no way how vacuum leaks can cause a too rich mixture.

You could also install an adjustable FPR and set it to a very low pressure, such that it will compensate for the excess fuel. But that's no real solution.

While I appreciate you trying to help, your answers are becoming distracting.

He absolutely doesn’t need an adjustable fpr.

Until he has both good cam and crank sensors we cannot troubleshoot any further. He does not need to spend money on other parts till those are verified.


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[DSGBUILT]

While I appreciate you trying to help, your answers are becoming distracting.

He absolutely doesn’t need an adjustable fpr.

Until he has both good cam and crank sensors we cannot troubleshoot any further. He does not need to spend money on other parts till those are verified.


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I can Confirm that the crankshaft position sensor is Good but can’t do so with the camshaft one. I heard people say that the OBD1 camshaft Sensor cannot be testef. I don’t know who to believe because my sensor that I had on the car didn’t read no resistance and so was the new sensor that I got to try to replace that one with. I can try and order a Genuine sensor And try to see if it has any resistance and If not return it, if somebody has a definite answer for me and knows 100% that a camshaft position for a 94 325 OBD1 can definitely be tested with a voltmeter on a 0HM setting using the first and second pin

[DSGBUILT]

I ordered a brand new genuine BMW cam shaft position sensor hopefully this one is different from what I had before, If not I’ll just return it

[s13flyboy]

Sorry, missed the OBD1

[ed323i]

Volloso, you're right about the adjustable FPR, but I already wrote that was no real solution.
It would be interesting though, to diagnose the problem and see if it would run fine if you'd drop the pressure a lot. Then you know a lot more: it's fuel related and not crank/camshaft pos. sensor related. I don't see how a bad crank pos. sensor or camshaft pos. sensor would cause such low AFRs. It just doesn't seem logical to me.

If the DME is able to send the right ignition timing to the coils (as it is able to run, but then floods), the sensors are at least working sufficiently to have it idle. If the DME has trouble reading a proper signal from the crank/camshaft pos. sensors it won't know when to spark the coils, AND it won't know when to inject fuel, and I guess it will stop doing both at the same time (no spark, no fuel), or if it does receive a good signal, it wil supply both, spark and injection. I really don't see how these sensors, when bad, can cause AFR's in the 8-range. I would consider it very sloppy programming of the Bosch Motronic engineers/programmers if bad crank/camshaft position sensor readings would cause the engine to flood (as in: just keep on injecting, but ignore that there is no spark).

Another interesting test, which would give the same/comparable insight as the adjustable FPR, is going back to the original injectors (going back to stock, like advised earlier), and original EPROM chip, and see if it runs then.. Just disconnect MAF. Should run fine (assuming you didn't install another camshaft or other major internal engine modifications). As long as you don't spool the turbo, the engine should run fine, if the current problem is caused by the DME/injector-combination (incorrect tune installed) or by the MAF sensor.

If it's caused by crankshaft position sensor or camshaft position sensor, then it will still run badly, and, perhaps, against all (my) logic, still show AFR's in the 8-range.

In that sense, IF it's one of the position sensors that's causing problems, I have more reason to suspect the crankshaft position sensor, as the camshaft pos. sensor was already replaced by a (new?) one (right? #33), so there is 99% chance it's working fine, and disconnecting the camshaft sensor didn't change anything (while engine should run fine on just the crank pos sensor). So, if one of the two sensors is bad, my bet is it's the crankshaft pos. sensor. It's resistance/ohm reading is quite out of range (800-ish) instead of the 540 (forum) or 1240 (Bentley).

Also, to exclude the possibility of a bad oxygen sensor: If you can somehow hard-reset the DME (so the stored fuel trims are deleted), and then disconnect the oxygen sensor, you can take the influence of the oxygen sensor out of the loop (just let it idle and do not put load on engine, and do not spool the turbo to be safe).

[DSGBUILT]

Volloso, you're right about the adjustable FPR, but I already wrote that was no real solution.
It would be interesting though, to diagnose the problem and see if it would run fine if you'd drop the pressure a lot. Then you know a lot more: it's fuel related and not crank/camshaft pos. sensor related. I don't see how a bad crank pos. sensor or camshaft pos. sensor would cause such low AFRs. It just doesn't seem logical to me.

If the DME is able to send the right ignition timing to the coils (as it is able to run, but then floods), the sensors are at least working sufficiently to have it idle. If the DME has trouble reading a proper signal from the crank/camshaft pos. sensors it won't know when to spark the coils, AND it won't know when to inject fuel, and I guess it will stop doing both at the same time (no spark, no fuel), or if it does receive a good signal, it wil supply both, spark and injection. I really don't see how these sensors, when bad, can cause AFR's in the 8-range. I would consider it very sloppy programming of the Bosch Motronic engineers/programmers if bad crank/camshaft position sensor readings would cause the engine to flood (as in: just keep on injecting, but ignore that there is no spark).

Another interesting test, which would give the same/comparable insight as the adjustable FPR, is going back to the original injectors (going back to stock, like advised earlier), and original EPROM chip, and see if it runs then.. Just disconnect MAF. Should run fine (assuming you didn't install another camshaft or other major internal engine modifications). As long as you don't spool the turbo, the engine should run fine, if the current problem is caused by the DME/injector-combination (incorrect tune installed) or by the MAF sensor.

If it's caused by crankshaft position sensor or camshaft position sensor, then it will still run badly, and, perhaps, against all (my) logic, still show AFR's in the 8-range.

In that sense, IF it's one of the position sensors that's causing problems, I have more reason to suspect the crankshaft position sensor, as the camshaft pos. sensor was already replaced by a (new?) one (right? #33), so there is 99% chance it's working fine, and disconnecting the camshaft sensor didn't change anything (while engine should run fine on just the crank pos sensor). So, if one of the two sensors is bad, my bet is it's the crankshaft pos. sensor. It's resistance/ohm reading is quite out of range (800-ish) instead of the 540 (forum) or 1240 (Bentley).

Also, to exclude the possibility of a bad oxygen sensor: If you can somehow hard-reset the DME (so the stored fuel trims are deleted), and then disconnect the oxygen sensor, you can take the influence of the oxygen sensor out of the loop (just let it idle and do not put load on engine, and do not spool the turbo to be safe).

interesting and i would definatly go over everything again, and yeah i replaced the crank position sensor and when looking over the camshaft sensor i couldn't get a resistance reading so i purchased a new sensor and nothing was different from the 1 had which made me believe the part was good then upon some reading i read that with an obd 1 car some people get a resistance reading so i figure i order a bmw sensor and check if i could get a reading, maybe i just lucked and got a bad sensor. i ordered it from autozone and it was supposed to be a duralast and when opening the box it was a bosch. maybe some one returned their old sensor in the box to get their money back who knows lol

[ed323i]

I collected some very interesting info with regards to the crankshaft and camshaft position sensors.. Here it is: #50 .
Conclusions:
1. The M52 MS41 DME runs perfectly fine with just one sensor connected, either one.
2. The MS41 runs better with a disconnected sensor than with a (slightly) failing sensor
3. It's of extreme importance to only buy the 100% original part: So with a Siemens DME (MS41) only buy Siemens sensors. With Bosch, only buy Bosch sensors.
4. Diagnosing the two position sensors just got a lot easier:
* Disconnect one sensor -> does it run fine -> you know for sure that the other sensor is 100% fine.
* Does it stop running or does it run very badly -> you know for sure that the other sensor is bad.

P.S. In your specific case, in which I think overfueling is problem, I'm not sure if you can apply conclusion 4 100%. Because the DME gets itself in a very complex situation with a missing position sensor AND an overfueling problem. So you might not apply the conclusions for 100%.
Also I assume Bosch Motronic 3.1 is as advanced as the Siemens MS41, so it can also run with just 1 sensor connected, but I haven't researched it completely yet. So, perhaps it only applies to the M52 MS41 DME and not to the M50 Motronic 3.1 DME.. I think, partially going back to stock (disconnect MAF, stock injectors, stock 325i tune) is the best next step now. You can also replace both position sensors, but be sure to use the original OEM ones (expensive though, but hey)..

[ed323i]

I remembered you noted an error code 1281:
From: http://www.318ti.org/forum/showthread.php?t=7211
1281 DME Memory Unit Supply This indicates a fault with the internal memory of the DME computer. This is sometimes caused by low battery voltage. Delete the codes, and disconnect the DME for 15 minutes. Then reconnect, let the car idle for five minutes, and then drive over 30 mph for more than five minutes. Recheck the codes - if it occurs again, the DME is faulty and should be replaced.


--

So, this indicates there is a problem with the DME.. Follow above instructions and see what happens. Perhaps the DME has died from static discharge during the replacement of the EPROM chip and is now malfunctioning? Do you have another DME you can swap?

Update: Sometimes this error resolves it self after resetting the DME, but in some cases it means the DME is fried.. See #2 .

Just another thought: It could also mean that the EPROM wasn't burned properly and has a checksum error perhaps? In that case, going back to the stock setup: stock eprom, maf disconnected, and stock injectors, might result in a good running engine. And then go from there, and perhaps ask for a new EPROM.

[glockroulette]

For what its worth i had a similar issue. ie, running pig fucking rich (8 and below) tried everything and it ended up being a maf that i fried when i wired it wrong the first time. verified it was fried.

new maf and new plugs later it was purring.

[DSGBUILT]

So I got a brand new sensor from BMW, the camshaft position sensor, and to all the people that said they can be tested You’re wrong . I also picked up A different DME from a buddy that I’m going to test later in the day to see if that has any effect on it. I’ll Keep you guys updated

[DSGBUILT]

So after Replacing the fuel filter,camshaft position sensor and the crankshaft position sensor and also swapping out to anther DME nothing changes.. I’m super lost and don’t know what to check for next .

[328iFun]

Put all the stock crap back on and see how the car runs

[DSGBUILT]

Put all the stock crap back on and see how the car runs

The only stock part I got is a maf, not sure I have the injectors left and the stock
chip

[328iFun]

The only stock part I got is a maf, not sure I have the injectors left and the stock
chip

I can send you injectors, I have a ton

if OBD1 and II are the same that is

[drstuess]

I would try and reload the tune on the chip if you haven't already. If you have a Moates it is super easy to burn the Eprom again. Most of this would be explained by stock tune.

Throwing stock injectors back on would confirm this as well. I would start there if swapping parts

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