MC2 misfires (continued)

[Dag Bøsterud]

I've reveived some great clues and hints so far about what makes my car (1990 100 Turbo Quattro Sport Exclusiv) misfire, but I've been driving the car some more now and "felt" the problem a bit more.

In the last 12500 miles I have replaced all sensors in regards to the engine except for the air intake sensor, new injectors, lots of new hoses. I get no fault codes. Oxygen sensor was replaced last summer.


Before the problem started: MTM ECU, original wg-spring, car boosted to 0,6-0,7 (1,6-1,7 on the driving computer). No problems, no misfiring.

When the problem started: MTM ECU, stiffer wg-spring. Car boosts to 0,6-0,7 (1,6-1,7 on the driving computer). When the car boost 0,6/0,7 you sometimes feel it holding back (probably starting to misfire) when you pass 3000 rpm, and when you pass approx. 4000 rpm it misfires.
This happens under load, so it always happens in 5. gear, but not always in the other gears.
If the car boosts less than 0,6/0,7, you may feel just a single misfire.

I have inspected the ignition cables, even did the water trick that was suggested, so they are OK.

This is driving me mad! :D

Any clues to what might be causing this?

/Dag

1990 Audi 100 Turbo Quattro Sport Exklusiv