car running bad....help.

[UDM Motorsport]

hi gruppe,
ok my car is running really bad now...here's the lead up to it.

Thursday - i installed a supersprint resonator (eliminating the cat converter)
Car ran fine on thursday.

didnt drive the car on friday.

Today: was planning to install new engine and tranny mounts.
Drove the car from parking lot into my garage - car revved really freely...felt really good.
Managed to swap tranny mounts. Attempted motor mounts but bolts are too hard to reach and tight. I removed the AFM and when i was reinstalling it, i heard this funny sound coming from the front of the motor - like a buzzing sound. after a while it went off.

Drove the car from garage to parking lot - car felt really bad, lt starts fine, idles fine and is fine upto about 1500rpms. Above this and the car vibrates alot, i thought it was the mounts, but the engine sounds like its struggling. Either its flooding or fouling....like its on 5 cylinders.

BTW my car is a 87 325is.

So what could possibly be wrong with the car now?

This symptoms is similar to what happen to my E30M3 - a bad O2 sensor. Could this be it? I dunno if its ever been changed.

Looks like the part number for the O2 sensor is 11 78 1 716 which is the car specific Bosch part. There is also a universal 3 wire Bosch part that will work with my car for 1/3 the price of the original unit. Anyone used this before?

Thanks for your help.
franklin

[Dominick]

i dont know what your problem is but it may have something to do with the AFM since you messed with it and it was running fine before.

and use a mustang 5.0 o2 sensor and just splice the sensor to the OEM connector. I dont know the link off the top of my head but search and you'll find it.

good luck

[atmh]

check spark plug wires and fuel injector wires. My car had a similar problem, it was running REALLY bad. I changed the spark plugs and it ran a lot better, but still a little rough, so I checked stuff and found my no. 5 injector wire was not hooked up (I just did an engine swap where i needed to change the wiring harness, must have not put it on good enough)

So check the basics first, and the AFM is definatly a possibility, cause that is what you did stuff to before it started getting bad. Check the o2 sensor after all those other things, unless you have good reason to believe THAT is the problem.

[UDM Motorsport]

Thanks for the info.

I'll swap out the spark plugs tomorrow to see how it runs.

I also dropped the AFM - maybe from 6 inches up when trying to reinstall.
Could that have knocked it outta whack?

If so, wonder if its a good opportunity to source the M30 AFM?

thanks
franklin

[atmh]

I just remembered something:

If you think one of the piston's is skipping, a great way to check is to start the car up with the hood open, then remove spark plugs one by one while the engine is running. If you remove a spark plug and it makes NO difference in the way the engine is running, then the problem is with that cylinder.

[Dominick]

great point

[65Matt]

Grab a spark plug wire while the engine's running and you'll learn something the hard way.