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E34 (1989 - 1995)

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  #1  
Old 11-29-2012, 08:06 AM
E34_Obsession E34_Obsession is offline
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Exclamation 1991 525i M50B25

Ok so a couple of weeks ago I disconnected the battery on my vehicle to charge it up (vehicle is a project car). After reconnecting the battery, it never wanted to start again. It seems like its not getting fuel, the car ran and drove great before disconnecting that battery. Spent the last days testing everything, the car does pop and/or fire while cranking but refuses to stay running. Checked almost everything that could possible be the problem via the Bentley Manual specs...
Fuel pump works and has good pressure...
Idle control valve, crank position sensor, and mass air flow are good...
Fuel filter is brand new and tank is half full with octane 93...
Timming is correct, has good compression...
Switched out fuell pump, dme, and main power relays with new ones, still nothing.
Checked all fuses, all seem to be good...
If I crank the car and continouosly feather the throttle, it will run, however it will sound like a john deere and it will quit running when I quit depressing the pedal....
All coils throw spark...
All six fuel injectors are brand new and car ran 3 months on them...
Seems to me like the DME Motronic computer is shot...
If my spelling is off sorry, it is uploaded from a mobile device...

PLEASE HELP! I LOVE MY BMW!
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  #2  
Old 11-29-2012, 08:25 AM
robertobaggio20 robertobaggio20 is offline
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It is possible that your battery or your alternator is busted. My money is on the alternator. Connect a voltmeter in parallel to your battery with the engine off. Anything less than 12.6v is suspect. Well, that might be the case here as the car has not been run for months, so look at the voltage reading with the engine on while at idle (as best as you can figure it) and while revving the car.

With your foot on the peddle, your voltage should not be higher than 14v or so. When at idle, it should be about 13.5 volts. When at idle and with all your lights and high beam on, the voltage may drop all the way to 13.0 volts...can't remember.....this would be normal. Do some googling about alternator behaviour, and check it out on your car. Highly likely that your alternator's voltage regulator is busted (which is why it generates too little current at idle to run the coils) and your battery is flat which is why it cannot compensate for the alternator for at least 30 minutes.

Check the Bentley manual for specific tests and figures. Actually, took a quick look. The alternator tests there are pathetic. Please google and youtube for more information.

Here's another quick and dirty test. Hook up jumper cables to another car, then start the donor vehicle, then start your own car. See if the bad behaviour you described above still holds while at idle. If it does not, then you've found your gremlin.

I'm assuming that you're unable to do the stomp test or read the codes off your vehicle. If you can, please do that.

If your dme is shot, your car will not start. All the dme screwed situations that we've seen here are no-start affairs.

Last edited by robertobaggio20; 11-29-2012 at 08:32 AM.
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  #3  
Old 11-29-2012, 09:33 AM
Josh429er Josh429er is offline
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Doubt It's the alternator, you would have had to charge your battery again. I doubt you could try and crank the car with success more than twice. It seems fuel related. Check fuel pressure if you can.
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  #4  
Old 11-29-2012, 09:37 AM
robertobaggio20 robertobaggio20 is offline
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Quote:
Originally Posted by Josh429er View Post
Doubt It's the alternator, you would have had to charge your battery again. I doubt you could try and crank the car with success more than twice. It seems fuel related. Check fuel pressure if you can.
Bad voltage regulator, or maybe its carbon brushes, or a busted rectifier, all in the alternator. Probably.....likely.....carbon brushes. It can charge the battery enough while being run at higher rpms, to support another start, but is not strong enough to run the engine at idle.
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  #5  
Old 11-30-2012, 10:03 AM
E34_Obsession E34_Obsession is offline
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Quote:
Originally Posted by Josh429er View Post
Doubt It's the alternator, you would have had to charge your battery again. I doubt you could try and crank the car with success more than twice. It seems fuel related. Check fuel pressure if you can.
Fuel Pressure is at a solid 42psi.
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  #6  
Old 11-30-2012, 09:43 PM
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Quote:
Originally Posted by E34_Obsession View Post
Fuel Pressure is at a solid 42psi.
It sounds like possible idle control air leak. Check sensor connections .Break out Bentleys manual and a multi meter start testing sensors , To rule out injectors I would prime a piston with gas. Later year 91 provided stomp test feature.
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  #7  
Old 11-29-2012, 12:55 PM
E34_Obsession E34_Obsession is offline
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Guys the motor pops and will not stay running. In order to keep it running i have to feather the throttle and it sounds and feels like its running on like 3 cylinders. Then when it quit its dies back out. Its not electrical or it wouldnt even pop or try to start which it is doing
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  #8  
Old 11-29-2012, 01:04 PM
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Monsignor Monsignor is offline
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Quote:
Originally Posted by E34_Obsession View Post
Guys the motor pops and will not stay running. In order to keep it running i have to feather the throttle and it sounds and feels like its running on like 3 cylinders. Then when it quit its dies back out. Its not electrical or it wouldnt even pop or try to start which it is doing
vacuum leak somewhere. Had the same problem on my z after i forgot to reconnect a breather hose on the intake tube.
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  #9  
Old 11-29-2012, 02:35 PM
robertobaggio20 robertobaggio20 is offline
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You are giving us bits and pieces of information, much of which is critical to diagnosis. This is due to either stress or inexperience. You are always going to be the best person to diagnose and fix any issue as you're standing right there at the car. I strongly recommend that you shoot a video of the car's behaviour and load it up on youtube or tinypic.com

Before you do that, check the Padre's suggestion. Check all vacuum hoses everywhere. Double check it. If its a vacuum leak causing this, it would have to be a huge one i.e. a large hose is almost totally disconnected. Check the hose that goes to the icv. Please also look through the engine driveability symptoms in the tables attached and check out anything relevant that you might have missed.

If that doesn't solve the problem then please get to that video. Shoot (with audio of course) from within the cabin, and then bring it to the engine bay and feather the throttle from the throttle cable directly. If you need to, please get someone to help you.
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Last edited by robertobaggio20; 11-29-2012 at 02:39 PM.
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  #10  
Old 11-29-2012, 10:11 PM
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I would go with air leak, or low battry, or Fuel pump.
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  #11  
Old 11-30-2012, 06:58 AM
E34_Obsession E34_Obsession is offline
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I will upload a video of the vehicles operation later today. I need as much input afterwards so I can fix it this weekend and get the car into paint. Thank you all for commenting.
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1991 BMW E34 525iA

1999 Toyota Tacoma Prerunner Xtracab 2.7L

2008 Toyota Tacoma Prerunner DCSB TRD Sport

1995 Toyota Tacoma 2WD DX V6 - SOLD

1992 Toyota Pickup - SOLD

2003 Subaru Forester 2.5X - TOTALLED

2004 Subaru Forester 2.5XT - SOLD

2005 Subaru WRX Sedan - SOLD
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  #12  
Old 12-02-2012, 08:40 PM
E34_Obsession E34_Obsession is offline
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Is it possible that my fuel regulator is bad?
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1999 Toyota Tacoma Prerunner Xtracab 2.7L

2008 Toyota Tacoma Prerunner DCSB TRD Sport

1995 Toyota Tacoma 2WD DX V6 - SOLD

1992 Toyota Pickup - SOLD

2003 Subaru Forester 2.5X - TOTALLED

2004 Subaru Forester 2.5XT - SOLD

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  #13  
Old 12-03-2012, 05:55 AM
robertobaggio20 robertobaggio20 is offline
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No.
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  #14  
Old 12-03-2012, 08:01 AM
robertobaggio20 robertobaggio20 is offline
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You were supposed to give us a video to help us help you. You were also asked to double check your vacuum fittings etc. Have you done that ?

Your problem sounds related to fuel delivery. There is a very simple test that you can do. Pull the fuel pump's fuse and start the engine. At some point, it will die. Keep cranking for around 10 seconds. No fuel will be left at the rails. Then, spray carburetor cleaner directly into your air box, or onto your air filter. Hold a good 15 second spray. Wait a few minutes, then start the engine. Once it fires up leave it without feathering the throttle. See if it lasts for a few minutes and see how it behaves in that time. A good 15 second blast will last for a few minutes on your engine. The incoming air will draw carb cleaner vapour in and that will serve as fuel.

Some members here feel that carb cleaner is bad for the engine. I don't think so, I've done this many times and its not an issue. In fact, the engine idles better...which is understandable as carb cleaner contains higher octane stuff than regular fuel. I've drilled a small hole into the side of my air box to permit easy access for the carb cleaner spray should I ever need it to start the engine etc. This hole is covered by some sponge at other times.

As an alternative to carb cleaner, simply douse your air filter in fuel, drip dry (not squeeze dry), and reinstall. Give it a few minutes to vapourise, then restart the engine. The incoming air will carry fuel vapour in with it, and this will run the engine. There is no risk of hydrolocking or anything like that. I've not tried this with fuel so I can't predict how long your engine will run. However, I've put in wet drip-dried filters before after rinsing them out with water, and I've never had a problem starting and driving the car immediately afterwards.

Thinking about it, if its a fuel delivery issue, all this can be done without pulling the fuel pump's fuse and purging the rails of gas first. Doing so wouldn't make a difference. So you can go directly to the carb cleaner or gas douse method.

In any case, if you do not do what we recommend especially if its something new and report results back, and if you do not double check stuff, you are not going to solve this problem. After awhile, people will not bother responding to you, and you'll end up towing your car to a workshop.

Last edited by robertobaggio20; 12-03-2012 at 08:05 AM.
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  #15  
Old 12-03-2012, 01:56 PM
snowsled7 snowsled7 is offline
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Quote:
Originally Posted by robertobaggio20 View Post
You were supposed to give us a video to help us help you. You were also asked to double check your vacuum fittings etc. Have you done that ?

Your problem sounds related to fuel delivery. There is a very simple test that you can do. Pull the fuel pump's fuse and start the engine. At some point, it will die. Keep cranking for around 10 seconds. No fuel will be left at the rails. Then, spray carburetor cleaner directly into your air box, or onto your air filter. Hold a good 15 second spray. Wait a few minutes, then start the engine. Once it fires up leave it without feathering the throttle. See if it lasts for a few minutes and see how it behaves in that time. A good 15 second blast will last for a few minutes on your engine. The incoming air will draw carb cleaner vapour in and that will serve as fuel.
Why? What is the point of this test? he reports that he has spark, and the car will run poorly. It will certainly run on carb cleaner but what is this telling you that you do not already know?

Quote:
As an alternative to carb cleaner, simply douse your air filter in fuel, drip dry (not squeeze dry), and reinstall. Give it a few minutes to vapourise, then restart the engine. The incoming air will carry fuel vapour in with it, and this will run the engine. There is no risk of hydrolocking or anything like that. I've not tried this with fuel so I can't predict how long your engine will run. However, I've put in wet drip-dried filters before after rinsing them out with water, and I've never had a problem starting and driving the car immediately afterwards.
This does not strike me as a very good idea. Gasoline vapor is extremely flammable. I can not imagine what the point of this exercise is either.

Quote:
Thinking about it, if its a fuel delivery issue, all this can be done without pulling the fuel pump's fuse and purging the rails of gas first. Doing so wouldn't make a difference. So you can go directly to the carb cleaner or gas douse method.

In any case, if you do not do what we recommend especially if its something new and report results back, and if you do not double check stuff, you are not going to solve this problem. After awhile, people will not bother responding to you, and you'll end up towing your car to a workshop.
The above post just wasn't any help, I might not respond if it was my post either.
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  #16  
Old 12-03-2012, 02:42 PM
robertobaggio20 robertobaggio20 is offline
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If you look through his list, he has changed and tested virtually everything that he needs to. He did read the bentley manual. So, there are only two possibilities, either he screwed something up when doing the various repairs/tests (solution is to doublecheck everything), or one of his new components has suddenly failed....rare but it does happen as **** happens, which means he needs to function as if this is a standard no-start issue, which means the usual suspects need to be tested.

And if this was a typical post, considering that his engine starts but dies shortly thereafter, it is a fuel delivery issue, and not a plug, coil, cps, dme, dme/main relay, fusible link, EWS2 or starter problem.

The OP has stated that this is a project car. Which means he should be grown up enough to handle himself around fuel without setting everything on fire.

In any case, unless he double checks everything, or posts a video, instead of trying to think through everything which has obviously failed which is why his car is not running now, its no point helping him and we should let him go to a mechanic.
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  #17  
Old 12-03-2012, 03:03 PM
snowsled7 snowsled7 is offline
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Just be cause you do not know what is wrong with his car doesn't mean he should be abandoned. Just because he doesn't respond to your incessant posting, doesn't mean he is beyond help.

You failed to describe what you were trying to accomplish by starting the car on something other than the fuel coming from the injectors...

Douse the air filter in fuel? seriously? Please explain to us why?
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  #18  
Old 12-03-2012, 04:11 PM
robertobaggio20 robertobaggio20 is offline
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Quote:
Originally Posted by snowsled7 View Post

You failed to describe what you were trying to accomplish by starting the car on something other than the fuel coming from the injectors...

Douse the air filter in fuel? seriously? Please explain to us why?
Please read my relevant post above....slowly.
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  #19  
Old 12-03-2012, 04:38 PM
robertobaggio20 robertobaggio20 is offline
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Originally Posted by snowsled7 View Post
Just be cause you do not know what is wrong with his car doesn't mean he should be abandoned. Just because he doesn't respond to your incessant posting, doesn't mean he is beyond help.
No one is beyond help snowy. Thats why i do bother to be firm with him.

And by now it should be VERY obvious, and increasingly so as time passes, as to what is wrong with his car.
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  #20  
Old 12-04-2012, 04:49 AM
snowsled7 snowsled7 is offline
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Originally Posted by robertobaggio20 View Post
No one is beyond help snowy. Thats why i do bother to be firm with him.

And by now it should be VERY obvious, and increasingly so as time passes, as to what is wrong with his car.
Who exactly are you to be firm with anyone here?

Yes, he obviously has either a fuel problem or possibly a DME problem. Either way, your suggestion of introducing some other flammable makes absolutely no sense

More proof that you are not qualified to be firm or even give advice in most cases.
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  #21  
Old 12-04-2012, 05:04 AM
robertobaggio20 robertobaggio20 is offline
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Quote:
Originally Posted by snowsled7 View Post
Who exactly are you to be firm with anyone here?

Yes, he obviously has either a fuel problem or possibly a DME problem. Either way, your suggestion of introducing some other flammable makes absolutely no sense

More proof that you are not qualified to be firm or even give advice in most cases.

No Snowy, those are not the real reasons why this car is not back on the road where it belongs. If you step back a little and think on it deeply, be just a little zen about it, you will understand what i mean.
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  #22  
Old 12-09-2012, 05:54 PM
robertobaggio20 robertobaggio20 is offline
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The air filter is doused with fuel as a substitute for starter fluid and for carb cleaner, two substances which invoke many pre-existing beliefs amongst festers that they would damage the engine. The entire procedure is done for the simple reason that it can unambiguously confine the faults to the fuel delivery system alone in one fell swoop. You need not test everything in turn over again. In this case, the car coughs and dies soon after a startup. Pull the fp's fuse, run the car until it dies thus purging the rails of fuel and thus preventing false positives from your test, does the filter, drip dry, reinstall, give it a few minutes to vapourise, start the car (hold the throttle open if you need to for the start then release) and see if it starts and idles normally after that.

If it does, it is not the ecu, not the crank sensor, nothing else except something related to the fuel system. The fuel system has too many intermediate systems which need to be checked individually, and when you feel you have already done so, it is generally unlikely as well, so reduce your time investment by using a quick and dirty method. Naturally, I use carb cleaner spray instead of gasoline because its handy and works very well.

Then, if this test is positive, you know you screwed up your fuel system doublechecks and you can redo everything again.

And if you are not an adult, insist on skipping posts, or are somehow unable to handle flammable fluids like bloody GASOLINE with appropriate care, then maybe you shouldn't be doing anything with a car, and should just take it to mommy or a mechanic instead in future.

Last edited by robertobaggio20; 12-09-2012 at 08:39 PM.
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  #23  
Old 12-14-2012, 07:18 AM
E34_Obsession E34_Obsession is offline
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Ok guys sorry I've been busy. Today I will post a video on youtube on the cars behavior. The car does not idle or run at all. If I crank and feather the throttle it will run like **** and stay running until I stop then it dies. Its hard to explain but I will show in the video. Sorry for the late response, I will get back to ya'll today.
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1991 BMW E34 525iA

1999 Toyota Tacoma Prerunner Xtracab 2.7L

2008 Toyota Tacoma Prerunner DCSB TRD Sport

1995 Toyota Tacoma 2WD DX V6 - SOLD

1992 Toyota Pickup - SOLD

2003 Subaru Forester 2.5X - TOTALLED

2004 Subaru Forester 2.5XT - SOLD

2005 Subaru WRX Sedan - SOLD
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  #24  
Old 03-13-2013, 07:08 PM
E34_Obsession E34_Obsession is offline
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Vehicle is up and running with a new DMe.
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1991 BMW E34 525iA

1999 Toyota Tacoma Prerunner Xtracab 2.7L

2008 Toyota Tacoma Prerunner DCSB TRD Sport

1995 Toyota Tacoma 2WD DX V6 - SOLD

1992 Toyota Pickup - SOLD

2003 Subaru Forester 2.5X - TOTALLED

2004 Subaru Forester 2.5XT - SOLD

2005 Subaru WRX Sedan - SOLD
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