Welcome to Bimmerfest -- The #1 Online Community for BMW related information! Please enjoy the discussion forums below and share your experiences with the 200,000 current, new and past BMW owners. The forums are broken out by car model and into other special interest sections such as BMW European Delivery and a special forum to voice your questions to the many BMW dealers on the site to assist our members!

Please follow the links below to help get you started!

Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > E34 (1989 - 1995)

E34 (1989 - 1995)

Thread Tools Display Modes
Old Yesterday, 09:44 PM
FabianE34 FabianE34 is online now
Location: Massachusetts
Join Date: Oct 2014
Posts: 8
Mein Auto: 1994 525i
Bad idle, shuts off

LOL my car is always giving me some problem as soon as i have plans to do something the next day but anyways, 1994 525i , when i start my car it idles around 400-500 rp,s and itll try to give itslef the power to stay on but itll die out. To keep it running i have to keep on pressing the gas pedal to keep up the rpm. It was misfiring so bad and i noticed a weird smell. I also did the stomp test and fault code 1215 came up which i think is MAF sensor. I took that apart and checked the intake box and the throttle body and it was all good, EXCEPT that i noticed a bit of motor oil in the throttle body. I'm not sure if it was like that when my mechanic put in a new motor for me or if theres an oil line/tube that can be leaking around the intake system. I cleaned the MAF and still did the same thing. Also cleaned out the throttle body. Honestly IM almost sure theres a vacuum leak somewhere because the brake pedal went stone hard while i was driving and would only be easy to depress if i floored the gas.
Reply With Quote
Old Today, 10:21 AM
ThoreauHD ThoreauHD is offline
Officially Welcomed to the 'Fest
Location: Virginia
Join Date: Feb 2006
Posts: 685
Mein Auto: 02/1994 530i 8cylinder
See the brake booster vacuum leak thread below. Also keep in mind that your MAF may simply have gone bad.
But as that is one of the most expensive parts on the car, explore the vac leak first.
Reply With Quote
Old Today, 12:57 PM
tristero tristero is online now
Registered User
Location: 805
Join Date: Mar 2014
Posts: 29
Mein Auto: 95 525i
When I was troubleshooting a misfire, at one point, I did get a MAF code. I sprayed it with MAF-cleaner, cleared codes, and it didn't come back.

(I did have oil in my spark plug wells, and I also changed my Valve Cover Gasket, just in case the misfire was caused by that oil; but my coil boots were also gunked and cracked, so I also replaced those and bought new plugs; one of my plugs was burnt - so ultimately, my problem could have been caused by ANY of that; including, maybe a loose intake boot on the throttle body that I snugged down).

What I'm saying is: sometimes, the root cause of these kinds of problems can be hard to pin-down, and your best bet is to check out everything that's a potential cause, and eliminate those causes as possibilities - and when you've got everything buttoned down, (which is not easy on cars this old) - it should run right as rain.

Idle issues seem to be primarily related to the Idle Air Control Valve, or problems with intake leaks, vacuum leaks, throttle body, or MAF. I think the MAF code points at the MAF, but it could also be an intake leak.

One great test for the MAF is to unplug it (at the connector) and see how the engine runs. (mine hunted like crazy) - some MAF failures will do crazy things. Try spraying it with some MAF cleaner (not carb cleaner! - harsh solvents can damage a MAF). You can hose-off any contaminants or deposits, dust, oil, or other crud that's sitting on the MAF and interfering with how it responds to air flow. If it's not burned out, that should clean up the MAF's behavior. Another thing to try, is if you have a known-good MAF from another car (same model) - then swap them. (otherwise, swap it with a brand-new MAF; which is costly, like $200-ish).

Otherwise, you can order new intake gaskets, throttle body seals, and probably injector seals, and start taking the whole intake plumbing apart, and look for leaks, and replace the seals and gaskets which are a primary source of leaks that will cause inconsistent behavior like this.

Idle Air Control valve is sort of a bypass to the throttle body - when that throttle-plate is fully-closed, the air flows through the ICV, and that's how your idle is controlled. So if that's leaky, or clogged, or the adjustment is off, that can affect your throttle.

These articles are some good background info:

Great DIY procedure:

ANother one with pictures (dead links though)
1995 525i M50TUB25 Automatic; 231k miles.
Reply With Quote


Forum Navigation
Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > E34 (1989 - 1995)
Today's Posts Search
Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On

Forum Jump

All times are GMT -7. The time now is 08:23 PM.

Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
© 2001-2011 performanceIX, Inc. All Rights Reserved .: guidelines .:. privacy .:. terms