95 S2Avant with slight misfire

[lee davenport]

seems to be more like hesitiaion than misfire - holding back type sensation really. that is why a friend thought it could be the timing being retarded to prevent damage due to hot charge intake temps

[Corey]

Ok, if it is a miss from the coils then it will be obvious at idle. It will be lumpy.
a hesitation is a whole new ball game

[AndersS2]

Ok, if it is a miss from the coils then it will be obvious at idle. It will be lumpy.
a hesitation is a whole new ball game

Sorry, just borrowing this thread a little.

Mine is lumpy on idle, same in hot or cold engine temp. It stays between 600-650rpm but jumps up and down like i couldnt stand still on 600rmp.
the car also tends to jump under heavy acceleration sometimes, resulting in a giant flame out the exhaust.
It almost stalls when approaching a roundabout or similar driving normally also, but reaches up to a 1000rpm before it stabalizes again.

..i thought it was the cracked head gasget (?) wich did this. (going for a new head job now in a short time).
but maybe it is the coils too then?

i had a similar symptom earlier, but that was fixed with new sparkplugs and Mark-H mod.
Now it seem more complex.

the engine (aby) is standard internally but is operating on a Turbonetics t60-1 charger and 044 fuelpump + 3 bar map sensor.

[lee davenport]

any suggestions on what causes hesitation? went for a blast tonight and in the cooler air it seemed as if the problem had gone or was too slight to notice. would faulty POS cause hesitation or would it be like coil probleme i.e lumpy and misfiring?

[nigelm]

misfire

This link helped me understand things.

http://www.sjmautotechnik.com/trouble_shooting/S4_Ignition.htm

In the first instance do check for loose plug (s) - is common.

nigeln

[phil2.016v]

I had hesitation/misfire on my ABY, it was fine one minute and lumpy the next. I purchased one of Corey's kits and everything is schweet!! Well recommended.

The problem is that kind of problem is hard to diagnose and you don't wanna chuck money at it trying to find out what's wrong. I have my OE coil packs in the garage, if you want you can borrow one to do a bit of testing?

[Sidspud]

It almost stalls when approaching a roundabout or similar driving normally also, but reaches up to a 1000rpm before it stabalizes again.

9 times out of 10 this is caused by a faulty ISV (Idle stabilisation Valve). Either clean it or replace it. Its the silver cylinder that sits at the rear of the engine bay near the throttle body.

[dan_b]

any suggestions on what causes hesitation? went for a blast tonight and in the cooler air it seemed as if the problem had gone or was too slight to notice. would faulty POS cause hesitation or would it be like coil probleme i.e lumpy and misfiring?

Hesitation and shoddy running is often caused by a duff lambda probe - the lambda allows the ECU to adjust the fuel mixture, but if it's faulty, the ECU goes rich, then lean, then rich, then lean etc. Results usually felt are hesitation, poor running, funny idle and poor fuel economy.

Replacement lambdas are about 60 quid - it is possible to check a faulty lambda using VAGCOM to see if it has been logged as an error by the ECU.

[stevieyid]

Can a lambda cause overboost protection? also how many POS are there?