M42club.com - Home of the BMW E30/E36 318i/iS

DISCUSSION => Engine + Driveline => Topic started by: achtungE30 on May 14, 2007, 09:25:54 AM

Title: Engine hesitates under high load after cleaning ISV and AFM
Post by: achtungE30 on May 14, 2007, 09:25:54 AM

I used carb and choke cleaner attempting to clean the ISV behind the upper intake manfiold plenum and the AFM while removing the factory airbox and installing a hot air intake (temporary).

Now driving the car around and testing it (at night), didnt get a look during the day, at some point in accelerating the car hesitated and a light quickly flashed and went out, located next to brake lining light. When I pulled back into my driveway, I tried revving the engine and each time i seemed to hesitate right after i pressed the gas but revved as it should have, kinda like a stutter or shake.

What could this be?

*EDIT* Some more info..
I did a tune-up last year, new fuel filter, plug wires, plugs, oil and filter, didn't touch the o2 sensor yet.
When I did all my vacuum lines, i had the intake manifold out and lower manifold as well, and cleaned the injector jozzles by hand as best I could while still inside the plenum.

Title: Engine hesitates under high load after cleaning ISV and AFM
Post by: Alpine003 on May 14, 2007, 04:04:10 PM

Did you make sure you don't have any vacuum hoses or sensor wires loose or detached?

I often see people that have problems after installing something or doing some maintenance after overlooking some part they forgot to put back.

Title: Engine hesitates under high load after cleaning ISV and AFM
Post by: achtungE30 on May 14, 2007, 08:51:07 PM

Pretty sure I had everything back in place. I'm worried the carb cleaner may have damaged a sensor in the AFM. I'll give it another look and see whats up :)

Title: Engine hesitates under high load after cleaning ISV and AFM
Post by: achtungE30 on May 16, 2007, 10:54:05 AM

Update:

No I didn't overlook anything...all hoses seem to be secure...but I do hear a vacuum leak someplace!!

Last year I replaced all the vacuum lines. Does the hoses that connect on the ISV need to be clamped at all? Everything else that previous had a clamp is clamped.

I will also go over my intake manifold and valve cover bolts just to make sure they are torqued to specs.

Anything else?

Title: Engine hesitates under high load after cleaning ISV and AFM
Post by: kowalski on May 16, 2007, 12:11:12 PM

i was under the impression carb cleaner was not sensor safe.

Title: Engine hesitates under high load after cleaning ISV and AFM
Post by: achtungE30 on May 17, 2007, 07:39:46 AM

So you theorize my AFM is shot now?

Title: Engine hesitates under high load after cleaning ISV and AFM
Post by: b318isp on May 17, 2007, 08:02:54 AM

The AFM track is inside the black casing and it is unlikely that any cleaner would have got to it.

Title: Engine hesitates under high load after cleaning ISV and AFM
Post by: kowalski on May 17, 2007, 10:03:27 AM

there is a sensor in the AFM is there not? As well as the ICV could have also ran into some troubles with the cleaner. I would try swaping them out with a friends, and see if the problem goes away.

Title: Engine hesitates under high load after cleaning ISV and AFM
Post by: Alpine003 on May 17, 2007, 11:27:08 AM

Quote from: achtungE30;25914

So you theorize my AFM is shot now?

Highly doubtful unless you have some cracks or holes in your AFM unit that would let cleaner get to some sensitive components. I've cleaned mine without any effect. I would try as others suggested and try swapping components.