My turn to ask for help :) (wayyy long)

[Robin-535im]

Okay Men (and Rina), here's the deal.

1990 535im, EAT, slightly agressive cam, 19# injectors, valves recently set to a snug 12 / loose 11.

Up until yesterday, everything was just fine. Yesterday afternoon I start the car, still fine. I let it idle for ~10 seconds, then start down the street. It sputters a bit... just a bit. About 200 yds down the road, just after stopping at a stop sign, the engine almost dies as I take off. I have to coast to the side of the road and let it recover. RPM's drop wayyyy low, giving it gas does nothing. 10 seconds of this, and the idle climbs back up, and the car is fine for the next few miles. Driveability is normal, lots of power, no lagging under any conditions.

Until I pull over to get gas. I let it idle for 3 minutes while I stepped out to look at an ///M3 for sale at the gas station, idle was just fine. I stop the car, get gas, start it again, and idle good for a few seconds then crappy, almost killing the engine as I u-turn out of the gas station. I have to put in the clutch and let the engine come back to life... then it's fine for the rest of the journey.

I get to the party, have a grand time, come back out and the car starts right up. I pull out, head home, but 20 seconds after I start out the car just about dies again. It comes back to life then the ride home is just fine. Runs like a champ.

I did some testing today, and it seems to only happen when I start the car. It feels like a huge vacuum leak, really lopy idle, much more than the standard m30 roughness. I pulled the dipstick while it was running, and it got even worse, so there is at least some vacuum in the system.

If I drive around then stop at a light, the idle is fine. If I park and shut it off for a few minutes then start it up, the idle is fine for a few seconds, almost dies, then comes back to life.

I'm thinking it's a leaky injector or fuel check valve... any one have any ideas? All comments welcome.

Thanks,

Robin

[George M]

believe your E-34 sputtered because it wanted to mate with that M3 you were looking at :-)
Robin...always start any driveability assessment with running your codes via the stomp test available on the '90 535i which had Motronic 1.3.
Let us know...then move on to checking sensors, vacuum, fuel pressure etc.
Good news is the M-30 is very straight forward to trouble shoot.

[Robin-535im]

Robin...always start any driveability assessment with running your codes via the stomp test available on the '90 535i which had Motronic 1.3.
Let us know...then move on to checking sensors, vacuum, fuel pressure etc.
Good news is the M-30 is very straight forward to trouble shoot.

Stomp test gave 1222 - which means? Bently's at home and Bruno n'est pas la. Of course, that was after I pulled the dipstick to intentionally induce a vacuum leak... Will have to clear and re-check.

The fact that it only happens on startup makes me think the Motronic is involved somehow... Perhaps a sensor is bad and the computer can't correct right at startup, but after running it figures it out and can correct.

I'm mostly hoping someone will have some insight that I don't. Right now the list of things to check is: vacuum leaks, fuel pressure, idle control circuit, leaking injectors, temperature sensors, DME, ... It'd be nice to have a smaller list. :)

[zmuff]

I had a similar experience with mine about a year ago...I wondered if I was even going to make it back home. I pulled over alot because of no throttle response, and then it would intermittantly run great. Got several check engine lights (1222--O2 sensor). Turns out that the clamp on the air tube between the AFM and throttle body was pretty loose and apparently sucking in doses of unmetered air. I had recently pulled the AFM and other stuff and just didn't catch it (head hung low in shame). Check your connections if you haven't already.

[Jr ///M5]

And the Bentley's sez.......Code 1222....Oxygen sensor lean/rich control stop.

Check for intake air leaks or reasons for rich mixture.


Hope it's something simple, yes...I agree with George, your car caught you looking at another ///M and now it's pissed...

Good luck,
Jr

[632 Regal]

kinda like a jealous old lady...till you kick their ass out of your world! Then stuffs good again! ya ya ya...bsck to the couch... :|

[Robin-535im]

And the Bentley's sez.......Code 1222....Oxygen sensor lean/rich control stop. Check for intake air leaks or reasons for rich mixture. Hope it's something simple, yes...I agree with George, your car caught you looking at another ///M and now it's pissed...

Good luck,
Jr

The car sputters for exactly 30 seconds, then runs perfectly fine after that. I think the DME is reading a bad temperature signal and floods it with gas during the cold start period, then when it gets out of the initial startup phase, the DME is fine.

Thanks for the info...

- Robin

[ryan roopnarine]

...i don't think its necessarily a "cold start" problem, 30 seconds seems to be enough time for the dme to compensate for the car to run passably for a lot of problems. when one of my icv hoses was (effectively) kinked shut, the car would studder a little at idle, take a little while to stabilize its idle from intermittent startup, then become ok with a high idle. it would increase in idle when i gave it gas. will elaborate some more when i get back home.

[Robin-535im]

Did the idle smooth out forever after the start-up period was over?