High idle, stumbling, surging...

[6erwebb]

Ive got it all you guys. I searched and no luck.

Ive done alot so far, my car is an early 86 eta manual.

The car was parked in 05 due to a problem...which I suspect is what Im on now.

The car starts like perfect, and will idle right on 750rpm... sometimes, other times it idles as high as 1700rpm and you can bottom out the icv and it still idles as high. The oddest thing is that you can let it drag itself at about 800rpm and it will stay there after a minute or so. But, as soon as you touch the gas pedal the rpm will climb again. Ive had issues with the car missing, like its only running on two or three. Ive had it to where you could start the car, and it runs fine for 10 seconds til it starts stumbling, shut it off and start again and it runs fine for another 10 seconds.

Also, worth noting is the fact that the car smells very lean though I havent checked plugs to confirm.


Ive had the injectors cleaned at MrInjector.

Replaced fuel with clean, new.

New fuel filter twice.

Different ICV and control module

Different ECU

different TPS

Different wiring harness

Different AFM

Different Fuel Injection relay

Different Main relay

SMOKE TESTED FOR VACUUM LEAKS (none)

CHECKED FUEL PRESSURE (35 or so at idle, jumps up around 40 when youre on it)

Verified spark at each cylinder.

New spark plugs and wires

New air filter

New Cap and rotor



Honestly the only thing I think I havent swapped out is the coil...


I really am simply at a loss, is there a part I havent thought to check?

-Webb

[jlevie]

Rail pressure on this engine should be 34-38psi off idle and something like 32psi at idle. So the rail pressure is well off if your gauge is accurate.

Swapping in a different ICV, TPS, ICM doesn't mean anything unless you have certain knowledge that those parts are good. And even then a fault in the wiring harness is a possibility.

You need to check the throttle body and throttle cable for binding and make sure that the TPS and throttle stop are correctly adjusted. Was the smoke test performed correctly? That means plugging the exhaust, replacing the AFM with a plug having a nipple for oil smoke introduction, and holding a smoke pressure of 2-4psi for at least 5 minutes.

[poplars]

thats interesting jim, does this mean that my having a hole in my muffler would impact the results of a smoke test?

if so I'll be busting out the JB weld and sheet metal promptly.

[6erwebb]

All the tests were done by a bmw tech who has worked on early bmws for years. Most of the parts were taken from known running cars. Except for the afm, I think Ill stop by the pull a part yard today and see if they have one... just to get a second opinion, not that we know if those cars ran or not.



-Webb

[6erwebb]

So I figured Id check the o2 sensor and got no voltage reading from the number 1 pin (3 wire system). The heater circuit is working, got 13 volts there! But nothing from the signal pin. Unplugged the thing and absolutely no change.

Im going to get a new one but could an o2 sensor cause all this?

[6erwebb]

..it wasnt.

[djmossm42]

What should the voltage be on the O2 sensor?

Sent from my SGH-T769