Engine in question is M103, 1989, 2.6L
Everything is in order from engine performance point of view:
(1) Idles normally ~650RPM (manual transmission, in neutral)
(2) Accelerates normally
(3) Fuel efficiency is normal
(4) Vacuum gauge is pegged all the way to the stop during idle
Has a rebuilt Fuel distributor that is about 20K miles ago.
ICV has been replaced and the behaviour has not changed at all.
Here is the issue that is a nuisance. I'm afraid it is a symptom that is going to get worse over time.
Issue is an idle "stumble" issue. About once a day, the idle jumps to 1100RPM from 650RPM, then corrects and stumbles.
This can happen 2 or 3 times in a row and the engine my stall the third cycle. But sometimes it just self corrects and this does not happen again the rest of the day. If there is a stall, there is no issue restarting. One quick strike and the engine is running again. During the stumble it appears Air Flow Meter drops to let in more air on its own. So it appears emissions related not ignition related.
Additionally during warm start if the car was sitting for more than 15-20 minutes if I crank the engine unless I give it gas, it will start and immediately stall. Second strike is always a perfect start. Cold start no problem, hot start no issue at all, ome quick strike and the engine starts.
Don't know if the two are related at all, probably not.
What can this be? Both are somewhat annoying but not detrimental at the moment.
Any help would be appreciated.
Everything is in order from engine performance point of view:
(1) Idles normally ~650RPM (manual transmission, in neutral)
(2) Accelerates normally
(3) Fuel efficiency is normal
(4) Vacuum gauge is pegged all the way to the stop during idle
Has a rebuilt Fuel distributor that is about 20K miles ago.
ICV has been replaced and the behaviour has not changed at all.
Here is the issue that is a nuisance. I'm afraid it is a symptom that is going to get worse over time.
Issue is an idle "stumble" issue. About once a day, the idle jumps to 1100RPM from 650RPM, then corrects and stumbles.
This can happen 2 or 3 times in a row and the engine my stall the third cycle. But sometimes it just self corrects and this does not happen again the rest of the day. If there is a stall, there is no issue restarting. One quick strike and the engine is running again. During the stumble it appears Air Flow Meter drops to let in more air on its own. So it appears emissions related not ignition related.
Additionally during warm start if the car was sitting for more than 15-20 minutes if I crank the engine unless I give it gas, it will start and immediately stall. Second strike is always a perfect start. Cold start no problem, hot start no issue at all, ome quick strike and the engine starts.
Don't know if the two are related at all, probably not.
What can this be? Both are somewhat annoying but not detrimental at the moment.
Any help would be appreciated.