Rough & Misfiring RPM, need advice.

[takumidrift30]

This is actually a continuation of my previous thread, decided to have a separate one. Anyway here it goes, basically got her just last week-1992 525i 5 speed (M50), was garaged for 4 months w/o starting, we only started her when we pick her up. Had a rough idle sound actually more like a misfiring from idle 'til 3,500 RPM, standing rev and moving. After 3,500 RPM as if nothing is wrong with it 'til 6,000 RPM.
Here's what I did:
1. Put new plugs
2. Bought 3 new ignition coil (As the previous owner says that it needs 2 igniter guess he meant coils upon testing found that it was 3).
3. Put new fuel filter, Fresh gas and injector cleaner.
4 Checked all the hoses & vacuum for leaks-found nothing everything is ok.

Results: for the few miles got a better idle and the misfiring like thing went down from idle to 2,000 RPM. As I used it today it went back to the same condition as when I got it. Rough idle at low RPM and misfiring like sound at high RPM. Planning to do today compression test.

I would appreciate any input at this point, thanks in advance!

[stu1]

Might well be worth just giving it a bit of a clear out. Get it out on the highway and just run it at 5000 rpm in 3rd gear for five minutes or so. Occasionally drop it down to 4000 and then hard accel up to 6000, then back to 5000.

[DABLACK]

were the coils (old) cracked or did they burst?
usually when this happens it messes up the dme/ecu
whatever whoever calls it (engine comp)
you might have to get a new one
just a thought I went through the same thing
check it out and let us know

good luck!

[632 Regal]

this sounds !

Might well be worth just giving it a bit of a clear out. Get it out on the highway and just run it at 5000 rpm in 3rd gear for five minutes or so. Occasionally drop it down to 4000 and then hard accel up to 6000, then back to 5000.

[BillionPa]

you might want to check the battery and alternator before you go high RPMs on it, and also do the plug boots on the other coils.

O2 sensor good?

[VentoGT]

Check the cap and rotor for moisture or corrosion...sounds like it well could be the culprit. You may not be running on all cylinders either.

[acidfire52]

I have this same problem with my M50. Mine also sat for several months before I bought it.
When I bought the car 2 months ago I do not remember the problem. Seems it started when I replaced the plugs with Platinums. Found out they such, replaced with copper plugs, still does it.

Was thinking it could be a problem with my VANOS. Does anyone know how to check to see if that is working?

Have also read it could be the MAF. Tried unplugging that, but it just ran worse.

[takumidrift30]

Thanks for the input guys! The O2 sensor is good, changed the boot plugs and the rest of the igniton coil-so basically all 6 coils are new, cleaned the throttle body and still the same. I did a compression test and the results were good w/c i wasn't expecting consistently at 200 psi except for #1 w/c is 190, but that is still good right?
Also I noticed as the engine temp. gets higher the roughness gets worst.
noticed also with the new plugs when I removed them, the tip or codes are dark (these are new plugs) so I would assume at this point that she is running rich?
Guys need your help how to address this problem, it's getting kinda frustrating at this point. Thanks again!

[takumidrift30]

you might want to check the battery and alternator before you go high RPMs on it, and also do the plug boots on the other coils.

O2 sensor good?

The battery is new too.

[acidfire52]

My battery and alternator are both new too.