The engine is my 242Ti has a hard time remaining at the same speed. I am not sure what is causing it. I do not notice it while under load (driving), the car does not buck, surge or anything like that.

Power and mileage is otherwise good, 19mpg last tank with mostly city driving and some good boost runs!

But while idling, if I raise the engine speed and hold it at a certain RPM. The engine will stay at that speed for a bit, then stumble a little drop 300-500 rpms, sit there for little bit then head back to the RPM I was holding. It will do this cyclically.

I have replaced the injectors (because i thought they were causing another problem, which actually I just needed hotter spark plugs).

I might have a vacuum leak but I am not sure, would it cause this kind of symptom. The engine pulls 20" when cold idling, and 22" when warmed up and idling.

take care

Luke
82 242Ti 168k miles
84.5 245Ti 300k miles retired due to condition... :( now parts car :)

http://home.ncn.com/~pcguy

Hi luke,
Inspect the oxygen sensor (bellow of your turbo), find the wire shield is bad or burned, then inspect the green wire if is well connected to this sensor.

Edwin

Edwin

Good thinking there. Last time I checked the 02 sensor the wiring looked ok.
Have to check the voltage, and see if it matters if I disconnect it.

I was thinking that maybe the base settings for the mixture were off, and thereby causing this condition.

thanks
take care

Luke
82 242Ti 168k miles
84.5 245Ti 300k miles retired due to condition... :( now parts car :)

http://home.ncn.com/~pcguy

Forgive my ignorance of earlier turbo engines but:
Does this type of turbo engine have Constant Idle Speed System CIS?
Seems like a good place to start.
Does your CIS have an Idle Air Control Valve IAC?
If so try cleaning it.
Good Luck
Karl

Karl
yes, the earlier turbo engines also use the Constant Idle Speed System.

Good thinking there. Maybe something is amiss, I wouldnt have thought to check that system since while the throttle is open, the microswitch does not tell the idle air motor to open and idle the engine. Guess it sure could.

thanks
take care

Luke
82 242Ti 168k miles
84.5 245Ti 300k miles retired due to condition... :( now parts car :)

http://home.ncn.com/~pcguy

I am assuming you are using Cruise Control and getting the variation in RPMs. If you have an automatic this is to be expected since the AW71 doesn't have a lock up feature for the torque converter. If you have the M46 with OD then the RPM's will drift with hilly terrain. Kick the M46 out of OD and see if the RPMs drift. Not good for the mileage if you do that.

"I am assuming you are using Cruise Control and getting the variation in RPMs."

Actually I dont have cruise installed on the car yet. I mainly notice it @ idle, and if I raise the engine speed and attempt to hold it there. Then it will stumble, drop, pick back up, and do it all over again. It might do it in gear, while driving around under load but I have not noticed it. The car acts quite normal under load.

"If you have an automatic this is to be expected since the AW71 doesn't have a lock up feature for the torque converter. If you have the M46 with OD then the RPM's will drift with hilly terrain. Kick the M46 out of OD and see if the RPMs drift. Not good for the mileage if you do that. "

I have an M46, I have not tested that yet. Good thinking, will have to try that and see if I can notice it in gear.

thanks
take care

Luke
82 242Ti 168k miles
84.5 245Ti 300k miles retired due to condition... :( now parts car :)

http://home.ncn.com/~pcguy