Running like shit

[CorvallisBMW]

I've been having a lot of trouble getting this engine to run well. Just some background, all the plugs, cap/rotor, other maintenance items are new or nearly new.

When running the Miller MAF/WAR combo it idles like shit when cold. In fact it'll die the first 1 or 2 times i fire it up. But once it's fully warm it purs like a kitten. A 1400rpm purring kitten :???:

So i switched back to the stock chip and afm. Now it idles even worse! stumbles while driving, sounds like it's going to die, hesitating, etc. Also seems to be running pig rich.

I know what I'd do on an m20. And it's all stuff I've already done. Any ideas from R3v's m30 crowd?

[kronus]

Injectors? CPS? Plug gaps? TPS/ICV? Vac leaks/smoke test?

[LowR3V'in]

Rip in your intake elbow?
Do you have any wires that you've spliced? Say for the afm, or anything like
that?

[chadthestampede]

o2 sensor faulty?

[CorvallisBMW]

Did some process of elimination. The stock AFM runs like crap because I had to rewire the plug for 12V to run the MAF, the stock AFM runs 5V. So that'll never work. But I did swap out the WAR chip for the stock chip several times and found little difference between the two, the only one being that once warm, the stock chip idles at 950rpm and the WAR idles at about 1200-1300.

Injectors? CPS? Plug gaps? TPS/ICV? Vac leaks/smoke test?

The engine came from a perfect running/driving car so I would assume the ijectors are find. I adjusted the TPS per factory procedure. Plug gaps were pre-set and I checked them before install. TPS seems to be working properly, but if it were bad the car would idle like shit all the time, not just when cold. I've checked dozens of times for intake leaks, literally, and can't find any.

Rip in your intake elbow?
Do you have any wires that you've spliced? Say for the afm, or anything like
that?

No wires spliced, though I did have to lengthen the TPS wire and the O2 sensor wire. I checked the splices, everything looks great there.

o2 sensor faulty?

Maybe. I put on the same o2 sensor from the car that the motor came from. Again, a running driving car. I would be surprised if it went bad turning transport/install, but weirder things have happened.

I've heard something about an 02 sensor heater on m3 cars, anyone know about this? Could that have something to do with it, the m20 harness doesn't have provisions for it or something like that?

Also, what is the proper way to check for functionality of the coolant temp sensor?

[for3ver]

DME temp sensor?

[brody]

Have you run through our troubleshooting manual for the MAF? It is available here:

http://millerperformancecars.com/files/Troubleshooting%20Guide.pdf

Our MAF conversions have been proven time after time for 4 years now, there has to be an external cause to the problem if the MAF specs all check out.

Are you sure you are running the right software on the WAR Chip when the MAF is installed? Try running the WAR Chip with stock software programmed on it?

[BDK]

my M535i was doing this, I unplugged the O2 (open Loop) and went out and blew it out, WOT, and came back and it was fine but a little rich...eventually I changed out the O2 and all was good...
has your AFM been opened, messed with? that can drive you crazy too...
Post on Mye28, the m30 guru's are good at this shit...