air filter woes

[MrK]

I just removed my OMP 'warm' air filter plus highbeam cooling duct to clean it up a bit and re-insert my highbeam, but things didn't go quite as planned:

I took out the filter, put in the highbeam, and then realized that the filter 'barrel' (thing that covers the filter and provides a hose connector to the outside) doesn't fit with the highbeam in. So I removed it completely, leaving the filter exposed, much like normal cone filters you see everywhere.

Trouble is, the filter then fell out and hit the alternator fan, bruising a few fins on the filter.

Now, my car 'hiccups' at random points on the rpm range while accellerating, but idles flawlessly.

Could this be because the filter is effed-up/clogged/damaged, or did something else go wrong?

Any help is appreciated.

[porsche gt1]

explain the hicupp.

[MrK]

alright, I changed the filter to a new one, and the hiccup remains.

Hiccup explained:

The car runs great when it's cold, but once it reaches operating temperature, the rpm starts giving a single jolt once in a while while idling, the jolt being upwards about 100rpms or so (not much). When accelerating, the car seems to cut off for a fraction of a second at random spots in the rpm range, with occasional valve knock during the jolt.

edit: the jolts during acceleration are strong enough to be described as gut-wrenching. I literally get pushed forward onto the locked seatbelt for a fraction of a second before the acceleration resumes.

I'm thinking maybe the AFM bit the dust. Is that the first thing I should swap, or should I look at something else first?

[Restoman]

It sounds like the filter flew around in there and hit some ignition stuff?

[SA E30]

Could either be AFM , depending on throttle position, or ignition... check the wires running to and from you alternator... they could have been ripped open, and be shorting against something, creating a loss in voltage, and hencea loss in spark.

Just a thought.

[MrK]

Ok latest development:

The car now runs like its possessed. On idle the rpm wildly varies between 2000rpm and 600rpm, and the jolts occur ALL THE TIME while driving, rendering the car totally undrivable. I've tried swapping the AFM, swapping the ECU, and playing around with the adjustable cam gear (I thought maybe it wiggled loose-- it hadn't). The car's condition gets worse the more I run it, popping, backfiring, stalling etc.

What could POSSIBLY be doing this? I'm beginning to think that it has absolutely nothing to do with the filter.

[SA E30]

Hmmm... fuelling problem ?

I had a similar problem last week, when my no.6 injector stuck open... but the car would pop and backfire all the time, all miss-fired badly.

Sorry I can't be more help.

[MrK]

Hmmm... fuelling problem ?

I had a similar problem last week, when my no.6 injector stuck open... but the car would pop and backfire all the time, all miss-fired badly.

Sorry I can't be more help.

I'll be sure to check the injectors then, but I doubt it could be a fueling problem, since I have a fuel pressure gauge installed, and it's giving stable readings.

Thx for all the help so far... keep em comin:)

[HST]

did you check the plug wires and distributer.

[MrK]

I checked the injectors, plug wires for spark (the force is strong in them), and the distributor. They all check out fine...

I'm stumped!

[SA E30]

If u say your ECU, AFM, Plug Wires and Dizzy and Injectors are all workin fine... then ur car should be running 100%

This is weird.

Only other thing I can think of is that the timing is out... maybe the filter cause the belt to jump a tooth or something ? I dunno.

[MrK]

Ok it turns out that it was the chip on the ECU. Got fried. The reason I didn't catch it earlier was because I swapped in a 320i ECU and the problem remained. I didn't know it was 320i ECU, so I thought the ECU was fine. When I tried a 325i ECU (173), the car stopped going crazy.

Thx for all the help guys, esp. SA E30.

[SA E30]

Ahh, so it was something simple... glad u got it sorted.

[mikeedler]

just to let you know, the 320i computer is the exact same as a 325i computer. the problem you were probably having is that the AFM wasnt matched to the comp.- I had that problem with a car of mine a few years ago also, and had the same problems as you.