1990 Coupe 2.3E 10v - jerkiness/poor driveability

[Doyt W. Echelberger]

Here is a report I wrote back in 1998 on a bucking problem in a different
model Audi, but it was a 10v 5 cylinder. It may give you some other options
to try.....Doyt Echelberger

This is a report of success in correcting a frustrating and stubborn low
RPM drivability problem in a 1986 4kq.  Vehicle could not be driven at
1,600-1,800 RPMs in any gear at a steady pace without alarming power train
clanking surging and bucking. Acceleration was good and operation at higher
RPMs was acceptable but a little thready.

After replacing wires, plugs, cap and rotor, the problem remained, although
improved by about 50%.

Reducing the plug gaps to 0.028 made the problem worse. Increasing the plug
gaps to 0.040 greatly improved the condition but didn't eliminate it.

Dismantling the distributor and physically checking the centrifugal weights
and springs disclosed no problems. Vacuum advance tested good.

RETARDING THE TIMING by 3 degrees (at idle, from whatever it was originally
set at) solved the problem completely. The vehicle now smoothly cruises at
very low speeds in all 3 lower gears without surging or bucking, with no
problems in either deceleration and acceleration. After the timing
adjustment, I put the plug gaps back within factory limits and found no
changes in performance.

Doyt Echelberger


 >>>>>>>>>>>>>>>>>>>>>>>
Dear Listers,
I wonder if you can offer any ideas on the following? It seems to have
confounded both my local Audi dealer and a Bosch Injection specialist...
The engine has recently started bucking, or jerking under very light
throttle openings - both as I go on the gas, and as I come off it. If I
hold the throttle in the same position, the car will continue bucking in a
most unpleasant way. Putting my foot down seems to smooth everything out -
it's really only a problem if the throttle is held steady with the car
under light load........snip