please help me! unusual problem... - BMW Forum

tahoenj · 07-08-2011, 09:38 PM

no one seems to know. clogged cat? bad sensor somewhere?

suddenly check engine light came on. i managed to buck and bog it back to work. when i start the car the idle goes from about 500-1200 up and down like breaths. when i put it in gear and try to go the car bucks and bogs. sounds fine when i rev it in neutral. the exhaust has been loud for a while now but there is no holes in the muffler and the loud sound comes out of the tips. the car is undriveable.

please please help i do not have the cash to bring this to a shop. - 92 325i

Thanks!

ltafta · 07-09-2011, 01:56 AM

I'm looking for some help on my issues but to give an opinion I, and others will want more information. Error messages or codes of any kind. I know I got the pulsating idle you described from a leak in the intake between the filter and the throttle body. Look for dry cracks in the rubber.

tahoenj · 07-09-2011, 02:25 AM

thanks ill check that out in the morning.. i dont have a computer to scan for a code though.

Jack Dabsy · 07-09-2011, 06:09 AM

Could be the Cam Sensor...
Just a thought !!

ltafta · 07-09-2011, 06:20 AM

you can get engine codes by doing what is called a stomp test. It amounts to turning your key to the run position and pressing the accelerator to the floor five times in five seconds then the check engine light will flash on for 2.5 seconds then off for 2.5 seconds then a series of four numbers begining with one. Each number is seperated by a breif delay. Here's a page that explains it and has the code meanings.
BMW E34 Check engine light stomp test

Jack Dabsy · 07-09-2011, 06:29 AM

Not heard of that one !!! Does it work on Euro spec BMW's ?

tahoenj · 07-09-2011, 10:48 PM

mine is a 3 series that stomp test is for the e34 5 series (apparently) i did try it in my car anyway and it didnt work.
im reallly leaning towards a clogged cat. any thoughts on that?

copcarguyp71 · 07-10-2011, 09:34 AM

While I have not had this problem myself I would not think the Cat since it was sudden and not a slow degredation of performance. I think the better possibility is a vacuum leak somewhere under the hood. If the stomp test does not work out then call around to Advance Auto or Pep Boys around you to see if they will plug in an anylizer for you...many of them will do it for free. If you were closer I would offer to use mine! Good luck and keep us posted, we can all learn from this one.

Jack Dabsy · 07-10-2011, 10:24 AM

Cam Position Sensor OR Idle Control Valve... Trust me !!!

tahoenj · 07-10-2011, 02:05 PM

Hey so I tried the stomp test again and it worked! (you gotta start stomp IMMEDIATELY after you switch the key on) Anyway, I got a 1215 which is an Air Mass/Volume Sensor so I ordered the part. Autozone- $199 Pepboys- $245 and Advance Auto- $85 plus $45 core. Needless to say I went with Advance, it should be in on Tuesday or Wednesday and I'll let you guys know!

Jack Dabsy · 07-11-2011, 02:46 PM

Its called MAF - Mass Air Flow sensor... This tells the ECU how warm and how much air is entering the system and compensates for it in different ways...
You could have an air leak somewhere else which would cause the MAF to give wrong signals etc...
Have a good look at the hoses/gaskets etc...

tahoenj · 07-11-2011, 09:23 PM

The results are in! There's actually a hose coming off the bottom of the tube after the MAF, closer to the motor that was all split and fell off. I got some epoxy and a hose clamp, problem solved! $5. Canceled the order for the MAF. Success!! Thanks to all

Jack Dabsy · 07-12-2011, 02:21 PM

Happy Days Now !!