<Have you been to my website? Have you used deoxit? Have you REMOVED the
intake boots to inspect for vacuum leaks?
Do these things first.
The legendary idle/bucking problems: If your motronic car starts to idle
funny, first thing you should do ...>
Thanks for your response- it is greatly appreciated. I am still hunting down
a driveability problem with my '91 16V Motronic GTi. I have used the
archives of this site as well as other sites to assist in my diagnosis of the
problem. Without the assistance of the knowledgeable members of this group,
I would be much further behind certainly less informed.
I have indeed sprayed each and every under-hood connection with a contact
cleaning spray (although not De-Oxit). I have ensured that the A/C hoses are
not resting on the fuel distributor harness. I have also:
1. replaced the O2 sensor with a Bosch O2 sensor with no
improvement
2. replaced a faulty coolant temp sensor
3. replaced the distributor cap with a Bosch cap
4. replaced the main fuel filter with a Bosch filter
5. replaced the spark plugs with OE Bosch plugs
6. blown out the idle air stabilizer valve with cleaner with no
improvement
7. looked for and found no significant vacuum leaks at all
points in system
8. sprayed carb cleaner at fuel injectors with car running to
test for intake leaks
9. been to the dealer looking for open recalls on the vehicle-
none
The OBD (using the poor man's LED version) now indicates that the idle air
stabilizer valve is faulty or has faulty wiring. I have attempted to
complete as many electrical tests that I am capable of from the Bentley
manual. I have determined that the idle stab valve is getting 11.66V, and
that there is continuity between terminals of the valve. According to
Bentley, that checks out good. However, I do not notice any "buzzing" or
"humming" of the valve when the car is running.
The symptoms are an erratic idle- the tach needle jumps from 950 up to about
1800 RPM and there is a definite hiccup in the idle when this occurs. I
really seems like the fuel is being shut off intermittently at idle.
Sometimes when the A/C is switched on and off it will kill the engine. When
I listen to the fuel distribution manifold with a mechanic's stethascope, I
can hear a definite burble and cut-out in fuel delivery.
Before I throw more $$$ replacing components, has anyone else had these
symptoms? Any ideas I can pursue before trying to find an expensive
troubleshooter?
I really appreciate everyone's input on this board! You have helped a lot
already! What an education!
Jon
