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E34 (1989 - 1995)

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  #1  
Old 08-25-2013, 07:08 PM
N5673U N5673U is offline
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Mein Auto: 95' BMW 540i
95' 540i MAF (Idle Issue) HELP!!!

Hey Guys Isaiah here,

I have a 95' BMW 540i with almost (about one hundred short) 186,000 miles on it. I'm having issues with the idle of the car, there is a misfire and an overall shaky idle. The tach seems to stay in one place for most of the time but the car just shakes when it idles. I have to have the MAF unplugged to be able to get it to start when the engine is cold or else if it is plugged in, you have to give it gas to keep it from stalling. I also get a bunch of codes with the MAF plugged in, 1215 (MAF), 1222 (Oxygen sensor lean/rich control stop), 1213 (Oxygen sensor #2 lean/rich control stop), 1221 (Oxygen sensor #1), and lastly 1212 (Oxygen sensor #2). Could it be that the MAF is dirty and that is causing the shaky idle. Any ideas? I have no idea where to go from here, I have checked the cables with a multimeter and they indicate the correct voltage. Anyone ever had any issues like this before, by the way this is "rv6rick's" former car. I also read through the long epic post about the car and to no avail. Please help, if you need more info or anything I might have forgotten to put on here just ask.

Thanks,
Isaiah.
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  #2  
Old 08-25-2013, 07:16 PM
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E34ZombieHunter E34ZombieHunter is offline
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How is the filter, you could try to clean the MAF for good measure.
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  #3  
Old 08-25-2013, 07:24 PM
N5673U N5673U is offline
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The Air filter is fine, it was replaced not all that long ago and I have taken it out periodically and shaken out the loose bits of typical debris. I guess I will try and clean it, just regular MAF cleaner right?
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  #4  
Old 08-28-2013, 08:23 AM
N5673U N5673U is offline
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No one else has any ideas on what could be causing the MAF to not work???
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  #5  
Old 08-28-2013, 09:15 AM
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your car is showing alot of separate symptoms. I'm by no means an M60 afficionado but I would start with cleaning the MAF. MAF cleaner or regular carb cleaner will work.

If you do this and still find a shakey idle, try to source a known good used one and try that. From there, i'd be looking for vacuum leaks but probability that that is your issue is low.
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  #6  
Old 08-28-2013, 09:31 AM
Mr._Graybeard Mr._Graybeard is offline
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Have you gotten a manifold vacuum reading with a vacuum gauge? Vacuum leaks are the first thing I'd check for on an M60 engine with shaky idle and O2 sensor codes. If it's under 17 hg/in, you've got a leak.
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  #7  
Old 08-28-2013, 09:54 AM
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i was under the impression the idle was better with maf unplugged. Which is why i put vacuum leaks lower
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  #8  
Old 08-28-2013, 12:39 PM
N5673U N5673U is offline
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That's correct idle is better with the MAF unplugged. I'll see if I can get a hold of a vacuum gauge but right now it's not looking super promising, maybe in a week or so. I'll clean the MAF and see if it helps.

Thanks guys,
Isaiah.
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  #9  
Old 08-28-2013, 12:47 PM
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faulty MAF. replace it.
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  #10  
Old 08-28-2013, 05:34 PM
N5673U N5673U is offline
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I took out the MAF and cleaned it, it might have helped a tiny bit but I could barely tell, I would say you are correct on that it probably is faulty. The previous owner put it in just the first month or two of this year, he said it was from a salvaged bimmer.
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  #11  
Old 08-28-2013, 05:35 PM
N5673U N5673U is offline
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Any ideas where I can get a good MAF for a 95 540i at a decent price?
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  #12  
Old 08-28-2013, 07:31 PM
Mr._Graybeard Mr._Graybeard is offline
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Isn't this the RV6rick car? I just checked his thread from a few months ago (whew) -- he replaced the MAF sensor three times, twice with aftermarket parts and the third time with a used Bosch unit. Not that the used MAF couldn't go bad in a month or two (and two new aftermarket ones couldn't be faulty), but -- the car has seen a lot of MAF sensors recently if it's the former RV6rickshaw.

I also noticed while rescanning the thread that he was getting an unexplained trans program error. I did some intake work on my 540i recently and failed to plug in the throttle position sensor while buttoning it up. I got a trans program code at startup because the transmission reads the throttle position electronically. How's the transmission behaving, Isaiah?

I think about the only thing RV6rick did NOT replace or at least report evaluating was the throttle position sensor. Although it should throw a code of its own if it's faulty. Here's a link from our friends at bimmerforums.com. Just a wild shot in the dark.

Meanwhile, back to vacuum leaks: Isaiah, Autozone and Advance Auto part shops loan tools, and they often have a Mityvac available. It's a hand vacuum pump that has a vacuum gauge attached. That's what I use to measure manifold vacuum. It's quick and easy, and you can rule it out right away if it's not the problem. I've created a lot of vacuum leaks myself by leaving a hose unplugged somewhere.

Monsignor, that's why my suggestion was to check vacuum first -- it's an easy condition to diagnose and an easy condition to create by accident.

Last edited by Mr._Graybeard; 08-28-2013 at 07:33 PM.
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  #13  
Old 08-29-2013, 07:09 AM
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i had no idea the was THE RV6Rick's car! I agree with everything Greybeard said.
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  #14  
Old 08-29-2013, 06:02 PM
N5673U N5673U is offline
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Quote:
Originally Posted by Mr._Graybeard View Post
Isn't this the RV6rick car? I just checked his thread from a few months ago (whew) -- he replaced the MAF sensor three times, twice with aftermarket parts and the third time with a used Bosch unit. Not that the used MAF couldn't go bad in a month or two (and two new aftermarket ones couldn't be faulty), but -- the car has seen a lot of MAF sensors recently if it's the former RV6rickshaw.

I also noticed while rescanning the thread that he was getting an unexplained trans program error. I did some intake work on my 540i recently and failed to plug in the throttle position sensor while buttoning it up. I got a trans program code at startup because the transmission reads the throttle position electronically. How's the transmission behaving, Isaiah?

I think about the only thing RV6rick did NOT replace or at least report evaluating was the throttle position sensor. Although it should throw a code of its own if it's faulty. Here's a link from our friends at bimmerforums.com. Just a wild shot in the dark.

Meanwhile, back to vacuum leaks: Isaiah, Autozone and Advance Auto part shops loan tools, and they often have a Mityvac available. It's a hand vacuum pump that has a vacuum gauge attached. That's what I use to measure manifold vacuum. It's quick and easy, and you can rule it out right away if it's not the problem. I've created a lot of vacuum leaks myself by leaving a hose unplugged somewhere.

Monsignor, that's why my suggestion was to check vacuum first -- it's an easy condition to diagnose and an easy condition to create by accident.
Yes indeed, this is the very "RV6rick" problem car lol. The transmission is ok but it needs a flush for sure, sometimes it takes a good while for it to shift gears, other times it is great. I tried the other MAF he gave me with the car and it didn't even work, I cleaned the Bosch unit and that was a pretty much hardly noticeable improvement. Throttle position sensor, that's interesting... Thanks for the Autozone tip! I didn't know that they would have one, I'll have to go there when I get some time and give it a try. Thanks for all your tips Mr. Graybeard!
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  #15  
Old 08-29-2013, 06:04 PM
N5673U N5673U is offline
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Thanks Monsignor.
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  #16  
Old 08-29-2013, 07:08 PM
Mr._Graybeard Mr._Graybeard is offline
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Again, the TPS idea was just a shot in the dark, based on little more than the possibility that it hasn't been checked before. Good luck, Isaiah.
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  #17  
Old 08-30-2013, 07:30 AM
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the trans shifting time is variable based on temp. Cold car takes longer to shift.

Driving mine sotne cold it will hang in high revs in 1st for a while, kinda nerve wracking
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  #18  
Old 08-30-2013, 01:41 PM
N5673U N5673U is offline
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Thanks Mr. Graybeard! Shifting is variable based on temp....? Surely the cars weren't that way when they were brand new?
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  #19  
Old 08-30-2013, 01:44 PM
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Quote:
Originally Posted by N5673U View Post
Thanks Mr. Graybeard! Shifting is variable based on temp....? Surely the cars weren't that way when they were brand new?
My dad is original owner of mine and He was the one who told me that, after i asked him when my car wasnt shifting up to my standards.

I would even say new automatics are the same way.
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  #20  
Old 08-30-2013, 11:00 PM
N5673U N5673U is offline
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hmmmmm..... Interesting.....
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  #21  
Old 08-31-2013, 10:12 AM
Mamij Mamij is offline
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Bimmer Hero's Car ! Wow that was a true saga indeed. And he earned his monicker.

Welcome to the fest. Lets get your car fixed.

The M60 engine gets vacuum leaks only through bad intake manifold gaskets. Rick at that time clearly stated that the seals were good and reused them. He had removed the manifold as part of his investigations.

The only other way that you get vacuum leaks would be through loose hose connections, rupture hoses/fittings, or improperly tightened down stuff such as the rear ccv plate. All of this can be fairly easily checked by simple inspection and checking everything for tightness.

The other way to check for vacuum leaks is to spray carb cleaner at suspect spots (intake gaskets, throttle body, intake bellows, ccv plate, valve cover gaskets area, dipstick oring, anything after the maf basically) while the car is idling. If the idle suddenly improves when you hit a spot, there's one vacuum leak. The carb cleaner gets sucked in through the leak and is combusted, improving the idle temporarily.

Importantly, if you find one vacuum leak through this test, check the whole spectrum for other leaks as well.

Since this is Rick's car, he probably explained all of the above to you and you've done them to no avail. And you probably have the E34 bentley manual as well and have looked at its engine drivability troubleshooting lists.

Time to go back to basics.

The first basic is to do the stomp test and see if you have any useful codes. If there are any, clear the codes, then restart the car, drive for abit, and see if the same codes reappear. Sometimes you get transient old codes that are stored there which are not connected to the current problem.

You might have already done that.

The next thing to do (after you've confirmed that there are no vacuum leaks) is the drivability disconnect test. You basically disconnect each of the car's drivability sensors one by one, with the car running. As each sensor gets disconnected, the ecu switches to an onboard default map for that sensor or it ignores it totally. Once you hit the buggy sensor, the idle improves instantly.

The car's fault code registering system was not that advance for the E34 and the dme might still keep a fault sensor online and treat its nutty inputs as real, responding to it and generating a rough idle.

Only disconnect one sensor at a time and give it a minute to stabilise, reconnecting it before going to the next sensor. After the whole series has been done, clear all your error codes.

Your drivability sensors will be :

1. TPS (throttle position sensor).
2. ECTS (engine coolant temperature sensor)
3. MAF
4. O2 sensors (unplugging the relay should suffice if you can't get to the round pin socket easily and replug it easily as well)
5. IAT (intake air temperature sensor)
6. ICV (idle control valve). This is easily accessible on your M60 and you might want to just clean it out with carb cleaner with a shot of wd40 before reinstallation, just to rule out a dirty ICV.

The trouble is that sometimes unplugging 2 good sensors generates a rough idle all on its own. This greatly complicates an otherwise simple, quick and straightforward test.

The location of the sensors can be found on realoem.com, if you don't have Bimmer Hero handy to help you with this issue.

Another possibility might be a bad spark plug, injector or ignition coil. This is not that straightforward to quickly troubleshoot, so I will leave it to others here to advise. As for ignition coils, just unplug each on in sequence while the engine is running. The rough idle should get worse when you unplug a good coil. If you unplug a coil, and the idle remains exactly the same as before, you've localised the problem.

Come to think of it, this would work to isolate the chamber responsible. THEN, you can troubleshoot as to whether its the ignition coil, spark plug or the injector on that chamber which is specifically at fault.




From what I remember, Rick had 3 separate problems, and one unresolved issue on his car.

1. Cylinder wash due to quick cold starts and shutdown. Nikasil engines slightly more prone to this. However a good ects should not cause this problem regardless. The ects was changed to a new oem unit.

2. Bad maf. Now he had been driving for 2-3 years before this January, with a bad maf. He merely disconnected it. The idle was perfectly normal. We persuaded him to purchase a good used oem maf unit to fix this and he did so. With MAFs, you can get away with a good used oem unit ($40). New ebay china copies ($75) are not recommended, even when compared to a used oem unit. New oem units are very expensive ($200).

3. Bad IAT. Coupled with an unplugged maf, this generated a bad idle. In fact, a very bad idle. The car was barely drivable. The problem was identified when he unplugged the IAT. He replaced it with a new oem unit, as I recall.

4. A trans program error, that came and went without clear cause and effect. Changing DMEs did not make any difference.

5. Switching on the a/c switch and/or flipping the fan's dial up somehow fixed a bad idle issue. Cause and effect unknown.

So yes, that jogs my mind. The 540i does run at a stable idle with the maf unplugged, and when plugged in the idle was rough. With the maf unplugged and the IAT busted, the car was nearly undrivable and even stalled a few times. I suspect that your current cleaned MAF is ok. One other sensor is not. If two sensors are busted, the car would be nearly undrivable Plug it back in, and proceed with the driveability disconnect test for the other sensors. You should find the problem within 30 minutes.

Good luck.

p.s. Rick's transmission was perfect. The car shifted like butter. He took great care of his tranny. If you are suddenly noticing unusual shifting, it could be related to the rough idle, specifically the tps usually.
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  #22  
Old 09-03-2013, 09:16 AM
N5673U N5673U is offline
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Wow Thanks Mamij!!!! I don't know if I'll be able to get to trying the elimination process today but, if not today then tomorrow. It would be great if it would just be some sensor and not going out and buying a new MAF. I have sprayed carb cleaner around the intake manifold and the idle seemed to increase but not a lot, I tightened up everything there, it just might have been a bit loose. The idle was still the same though after that and of course I cleaned the MAF and no change. Next comes the sensors, until tomorrow, I'll be dreaming tonight of a great idling car.
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  #23  
Old 09-03-2013, 09:19 AM
N5673U N5673U is offline
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Also, I would like to note that "Rick" ever since he sold me the car stated that "whatever happens, it's your problem now." So, as far as having his help, that's not ever gonna happen lol. I really appreciate you guys though, this is what I call a real community!!!!
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  #24  
Old 09-03-2013, 11:39 AM
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Monsignor Monsignor is offline
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do not spray carb cleaner as a form of smoothing idle. Its meant for carburetors, not fuel injected cars.

I have mamij on my ignore list for a reason. I suggest you do the same.
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  #25  
Old 09-03-2013, 12:40 PM
Mr._Graybeard Mr._Graybeard is offline
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Isaiah, if you haven't read Rick's no-start thread in detail. I'd suggest doing that. He chased a ton of dead ends to resolve what ended up being a simple flooding situation. He also did a lot of work you won't need (or want) to duplicate.

Remember that you're the only one on this forum who has his hands on the car. Everybody else here is just offering educated guesses.

This is a great learning opportunity. I suggest you get a copy of this book: http://www.amazon.com/Bosch-Fuel-Inj...rds=bosch+fuel. Read up, and you may be giving us advice before long.
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