Fuel Delivery Problems - SOLVED

[mrgraybeard]

Andrew -- I ordered a blue coolant temp sensor from the dealer (@$50) and will try the test you suggest when I get my car back and encounter the next no start. Even if the temp sensor is not the issue, I am not bothered by changing it out as it was not changed during the head repair (and may even be original to the car).

Geez -- $50! Cancel that order. You can get one from RM European for as little as $5 and change -- $17 if you want the OE part by Bosch.

[squirrelhill]

Geez -- $50! Cancel that order. You can get one from RM European for as little as $5 and change -- $17 if you want the OE part by Bosch.

Thanks for the heads up. I saw the Bosch part for a lot cheaper on FCP, but was unsure whether it was an OE part.

[mrgraybeard]

It doesn't say BMW on it, but BMW uses a Bosch engine management system.

I wouldn't hesitate to use the FAE part in this application, either. You can test it for function before you install it, and its reasonably easy to replace. Also, if you get it from FCP, they have a lifetime replacement warranty.

[Andrewk79]

I'll start with: I don't know how to fix this.

My 95 525i would only do this when it got REALLY cold out. I would get it running the same way, sort of, I would put fuse 23 in while cranking the and the motor almost catching. I burned out two starters over two or three years doing this. The last time it didn't start, it was Halloween and probably 50 degrees F, I installed a Tee-d in fuel gauge to watch the fuel pressure if it did it again. Hasn't happened since, the gauge is still installed.

I've swapped the GM (which made the frequency less), fuel pumps, fuel filter, plugs, battery, switched to 0W40 when it got cold out, etc...... If you find a fix can you PLEASE post it.

Unplug your coolant temp sensor, the next time this happens. Then crank normally.

And could you post a picture of the underlined bit above ? It sounds like a good general idea. I'll be doing some work on my engine soon and might want to do the same along the way.

OP, there is only one way to check/monitor fuel pressure and that's with a gauge the way m735is did. There's no quick and dirty method for this. However the above discussion was about slow injector leaks which accumulate overnight, and slow leaks in regulator diaphragms. There are (by contrast) good quick and dirty methods available for these. In fact, if you do them both, and you don't smell fuel, you can pretty much rule out those and thereby rule in the coolant temp sensor. Because that's a known issue for the E34, and leaky injectors and busted regulator diaphragms are not known issues for the E34 : they happen to happen.

And never buy anything from the dealer that is also available on ebay or on reputed and established online retailers like the one graybeard cited.

And you said your M5's rebuilt injectors were better than OE. Probably an exaggeration but if you can do tell us about it, what you observed before and after the injector rebuild, etc.

[shogun]

And never buy anything from the dealer that is also available on ebay or on reputed and established online retailers like the one graybeard cited..

Ebay? Do you know how many copied parts are offered there?
You have forgotten the quality and brand differences. Do not compare apples with oranges.
Sometimes my dealer is cheaper than any online retailer, when it comes to special items.

[Andrewk79]

Ebay? Do you know how many copied parts are offered there?
You have forgotten the quality and brand differences. Do not compare apples with oranges.
Sometimes my dealer is cheaper than any online retailer, when it comes to special items.

I've found ebay to be a brilliant source of oe, aftermarket and cheapo parts. Its also the first place I go to determine the fair price of a particular item.

And I usually only buy new stuff from ebay sellers with a high rep count and who offer the standard return policy. I've never had a problem with fake new parts. And as to good used stuff you can call or pm the seller and suss him out and make a judgment call. fwiw

[ross1]

Ebay? Do you know how many copied parts are offered there?
You have forgotten the quality and brand differences. Do not compare apples with oranges.
Sometimes my dealer is cheaper than any online retailer, when it comes to special items.

You are talking about a guy who washes out fuel filters

[ross1]

Unplug your coolant temp sensor, the next time this happens. Then crank normally.
.

Pretty sure if the DME sees an open instead of that sensor it'll go full rich, and stay there.

[Andrewk79]

Pretty sure if the DME sees an open instead of that sensor it'll go full rich, and stay there.

Even if it does, it will be a level that has been factory tested to produce zero startup problems under all anticipated temperature conditions worldwide. When a sensor is unplugged, the dme reverts to factory default values stored in its hard memory. So that's why this maneuver works.

[demetk]

Even if it does, it will be a level that has been factory tested to produce zero startup problems under all anticipated temperature conditions worldwide. When a sensor is unplugged, the dme reverts to factory default values stored in its hard memory. So that's why this maneuver works.

Prove it.

My experience with disconnecting the CTS is the engine will gradually start running worse and worse.

[Andrewk79]

Prove it.

Look at the relevant section in the bentley manual to understand what the cts does.

My experience with disconnecting the CTS is the engine will gradually start running worse and worse.

Then your experience is wrong. Or rather you drew the wrong conclusions from your observations, probably because you did not rule out all other possibilities.

If you unplug the cam sensor, the afm/maf, the iat, o2 sensor and the cts, you essentially have a carby engine. The purpose of these devices are to vastly improve fuel economy and engine power at all ranges, by precisely controlling the fuel/air mixture dynamically and in real time. When that is precise, combustion is efficient. And of course, all of these helped to control harmful emissions through the simple device of efficient combustion.

Now...did carby engines run worse and worse just because they didn't have all these devices ? No, they ran great, but they were notorious drinkers.

Unplug your cts now. Your engine should feel no different at all ranges and it will stay that way for years. However, your fuel bill will begin to show some changes. Basically, as long as any driveability sensor is off, you can expect a loss of up to 20% on your fuel economy, assuming your driving style (whatever it is) is unchanged.

If you unplug your cts and your engine runs worse and worse....something else is wrong. You need to troubleshoot the other driveability sensors.

[demetk]

I think you are wrong on this and I think you have no clue that you are. Have fun talking to yourself.

[Andrewk79]

You've given no rebuttal to my detailed explanations given earlier (which actually makes it easier to pick apart an argument if it is wrong). And you're saying I don't know what I'm talking about ?

[demetk]

" You are entitled to your own opinions, but not to your own facts."

Which you've neatly proven by giving no rebuttal to my detailed explanations given earlier (which actually makes it easier to pick apart an argument if it is wrong).

Rebuttal? Ah yes, I forgot that we're in a debating contest where he who debates the best, or the loudest, wins. You come here and start proclaiming that everyone else is wrong and that only you are right. Didn't your parents teach you any manners? You remind me of my ex. You're not her are you?

And do you even have an e34? My WAG for the day is that you don't. So prove it.

[shogun]

@Andrewk79: since you registered on 02-03-2017 you have posted about 80 posts and you post as if all others are beginners and you are the only one who can save them from making mistakes. Do us all the favour and calm down a bit.

Back to the subject:

Limited Operating Strategy (LOS)
In the event of a serious fault in one or more of the sensors or their wiring circuits, Motronic will substitute a fixed default value in place of the defective sensor. This procedure is often termed limp home. A serious fault occurs when the signal from the sensor is outside of its normal operating parameters. When operating in LOS the engine may actually run quite well with failure of one or more minor sensors. Since the substituted values are those of a hot engine, cold starting and running during the warm-up period may be less than satisfactory. Also, failure of a major sensor, ie the AFS, will tend to make driving conditions less easy. Once the fault has cleared, Motronic will once more accept the live signal from the sensor. The following LOS measures are taken in the event of a failure

Component..............................Action
AFS........................substitute values are calculated from the TS position. The load signal is fixed to 6.0 ms and the ignition timing to 20° BTDC once the TS contact is open.

ATS........................substitute value of 50° C . A code will not be set, and LOS will not commence until a minimum of 3 minutes after engine start and the engine idling for a minimum of 30 seconds.

CID sensor.............injectors are pulsed simultaneously

CO pot..................substitute value of 2.77 volts

CTS...................substitute value of 80° C if ATS value is greater than 20° .
if ATS value is less than 20° , substitute value of ATS value for first three minutes after engine start-up.

OS.....................substitute value, open loop control

TS.....................substitute values, restricted engine operation

CTS
The CTS is immersed in the coolant system and contains a variable resistance that operates on the NTC principle. When the engine is cold, the resistance is quite high. Once the engine is started and begins to warm-up, the coolant becomes hotter and this causes a change in the CTS resistance. As the CTS becomes hotter, the resistance of the CTS reduces (NTC principle) and this returns a variable voltage signal to the ECU based upon the coolant temperature.
The open circuit supply to the sensor is at a 5.0 volt reference level and this voltage reduces to a value that depends upon the resistance of the CTS resistance. Normal operating temperature is usually from 80° to 100° C.
The ECU uses the CTS signal as a main correction factor when calculating ignition timing and injection duration.


ATS
The ATS is mounted in the AFS inlet tract and measures the air temperature before it enters the inlet manifold. Because the density of air varies in inverse proportion to the temperature, the ATS signal allows more accurate assessment of the volume of air entering the engine. However, the ATS has only a minor correcting effect on ECU output.
The open circuit supply to the sensor is at a 5.0 volt reference level and the earth path is through the AFS earth return circuit.
The ATS operates on the NTC principle. A variable voltage signal is returned to the ECU based upon the air temperature. This signal is approximately 2.0 to 3.0 volts at an ambient temperature of 20° C and reduces to about 1.5 volt as the temperature rises to around 40° C.


CO pot
The CO pot mixture adjuster is a three wire potentiometer that allows small changes to be made to the idle CO. A 5.0 volt reference voltage is applied to the sensor and connected to the AFS earth return circuit. The third wire is the CO pot signal.
As the CO pot adjustment screw is turned the change in resistance returns a voltage signal to the ECU that will result in a change in CO. The CO pot adjustment only affects idle CO. Datum position is usually 2.50 volts. On catalyst equipped models, the CO pot has no effect and the CO is thus non-adjustable.

[demetk]

Thanks shogun. OMG, does that mean Andrew was right on this one? Who is this masked man?

BTW, with a VPN you can locate yourself anywhere in the world.

[Andrewk79]

Thanks shogun. OMG, does that mean Andrew was right on this one? Who is this masked man?

Do i sense a hug coming ?

[Andrewk79]

@Andrewk79: since you registered on 02-03-2017 you have posted about 80 posts and you post as if all others are beginners and you are the only one who can save them from making mistakes. Do us all the favour and calm down a bit.

I'm sorry, but when did I say that everyone here is a beginner? You for example, when have I said that you are wrong about anything, even though you post so much ? Would that be because you are factually right about most things? I've even asked you to confirm certain points I wasnt sure of.

I recognise that you're a learned man and I recognise and respect the continuous effort that goes into being learned. However, when others are wrong they should have the balls to accept that being pointed out and not just defend themselves with no credible reason as if they were children who can't accept being wrong about anything. This is bfc and not the disney channel.

And I have made mistakes and when others point it out I've acknowledged it explicitly. That is fair and matured. Graybeard pointed out a mistake I made recently, he did it decently, I acknowledged it and did so decently. Butters Stoch pointed out another mistake I made recently, but he did so snarkily, I acknowledged the error, and did so snarkily back.

If you provoke/insult me when you don't have to, you're probably gonna receive a counterpunch. I expect the same when I do the same. Fair is fair.

And yes, I do know alot about the car. Sorry for not signing up earlier.

[/B][/U]

Back to the subject:

Limited Operating Strategy (LOS)
In the event of a serious fault in one or more of the sensors or their wiring circuits, Motronic will substitute a fixed default value in place of the defective sensor. This procedure is often termed limp home. A serious fault occurs when the signal from the sensor is outside of its normal operating parameters. When operating in LOS the engine may actually run quite well with failure of one or more minor sensors.


Since the substituted values are those of a hot engine, cold starting and running during the warm-up period may be less than satisfactory. Also, failure of a major sensor, ie the AFS, will tend to make driving conditions less easy. Once the fault has cleared, Motronic will once more accept the live signal from the sensor. The following LOS measures are taken in the event of a failure

Less than satisfactory does not mean we have problems like hard starting. It means less than ideal performance (i.e less than satisfactory). A point I made earlier with demetk. Thank you for confirming what I said.

[shogun]

starting will be less than satisfactory or even a problem (depending on ambient temperature), because the Motronic uses for LOS the values of a hot engine when you disconnect the temp feeler, and not that of a cold engine. Normal operation is, that during start up from cold engine, the injector pulse duration is increased, means: to provide a richer air to fuel mixture and the pulse frequency is also increased. Also, in addition to the injector pulse duration increase the ignition timing is also retarded. Injector frequency and pulse duration and degree of timing retard depend upon the engine temperature both during start-up and immediately afterwards.

So simply said: that is the same like with the old cars with choke and carb and someone tries to start a cold engine without pulling the choke to make the air to fuel mix richer. Ever tried to start a cold lawn mower engine without pulling the choke?

[Andrewk79]

starting will be less than satisfactory or even a problem (depending on ambient temperature), because the Motronic uses for LOS the values of a hot engine when you disconnect the temp feeler, and not that of a cold engine. Normal operation is, that during start up from cold engine, the injector pulse duration is increased, means: to provide a richer air to fuel mixture and the pulse frequency is also increased. Also, in addition to the injector pulse duration increase the ignition timing is also retarded. Injector frequency and pulse duration and degree of timing retard depend upon the engine temperature both during start-up and immediately afterwards.

So simply said: that is the same like with the old cars with choke and carb and someone tries to start a cold engine without pulling the choke to make the air to fuel mix richer. Ever tried to start a cold lawn mower engine without pulling the choke?

I understand what you say. Unfortunately, it does not match physical observations. So your information must be wrong.


a. The E34s with hard or no cold starting that had bad cts's, had zero trouble starting after the cts was unplugged. This has also been seen here for years.

Computers can be programmed with default values RnDed at the factory, and can automatically do the needful on what it assumes to be a cold start even when the cts is unplugged. So if say its been 4 hours since the engine last ran, and the cts input is not available (because Ross unplugged it), the computer can be designed to assume its a cold start and utomatically richen the mixture and alter ignition timing at startup, and can automatically revert both aspects to normal after 5-8 minutes of engine run time when the engine will surely be hot (depending on the average rpm during that time).

In short, what we observe in reality, which is fact and not opinion, must be correctly explained by our reasoning. Facts and observations, especially consistent ones, cannot be forced to fit reasoning and consistent observations cannot be ignored if they conflict with current reasoning. The reasoning must be examined and abandoned if it does not match reality.

[shogun]

the Motronic is designed and fixed like that: the substituted values are those of a hot engine

and not like you wish: "the computer can be designed to assume its a cold start and utomatically richen the mixture and alter ignition timing at startup, and can automatically revert both aspects to normal after 5-8 minutes of engine run time when the engine will surely be hot"

That is how Limited Operating Strategy (LOS) works for lowest emission level possible, not only for BMW, that is standard, more here
https://books.google.co.jp/books?id=...0(LOS)&f=false

[Andrewk79]

this is so stupid. The answer is in shogun's extract.

CTS...................substitute value of 80° C if ATS value is greater than 20° .
if ATS value is less than 20° , substitute value of ATS value for first three minutes after engine start-up.

When the cts is not available, and the ats (air temp sensor) records less than 20 degrees (which would be the case on very cold starts), the dme subs in the ats's value to manage the engine's startup.

And the cts would not not be available if it has been unplugged. Without the ats also being unplugged of course.

And of course, from common sense, we know that the dme prioritises the cts over the ats, so if a damaged cts shows a wrong and much lower temperature than an (undamaged) ats, then the dme uses the cts's value.....and floods the chambers causing hard starting and sometimes no starts.

There. Neat.

[ross1]

I understand what you say. Unfortunately, it does not match physical observations. So your information must be wrong.


a. The E34s with hard or no cold starting that had bad cts's, had zero trouble starting after the cts was unplugged. This has also been seen here for years.

Computers can be programmed with default values RnDed at the factory, and can automatically do the needful on what it assumes to be a cold start even when the cts is unplugged. So if say its been 4 hours since the engine last ran, and the cts input is not available (because Ross unplugged it), the <script id="gpt-impl-0.3804832250621735" src="https://securepubads.g.doubleclick.net/gpt/pubads_impl_108.js"></script>computer can be designed to assume its a cold start and utomatically richen the mixture and alter ignition timing at startup, and can automatically revert both aspects to normal after 5-8 minutes of engine run time when the engine will surely be hot (depending on the average rpm during that time).

In short, what we observe in reality, which is fact and not opinion, must be correctly explained by our reasoning. Facts and observations, especially consistent ones, cannot be forced to fit reasoning and consistent observations cannot be ignored if they conflict with current reasoning. The reasoning must be examined and abandoned if it does not match reality.

Most of us here do not participate in order to debate, and you sir are debating the wrong guy. So I suggest you shut up, listen and learn then perhaps you can run your foul mouth at some other forum with less experienced members.

https://www.psychologytoday.com/blog...ut-know-it-all

[mboor]

What we have here is failure to communicate. Some men, you just can't reach.



Someone knows just enough to be dangerous.

[ross1]

What we have here is failure to communicate. Some men, you just can't reach.



Someone knows just enough to be dangerous.

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