Doing my head in!

[stevieyid]

After i thought i had sorted the hesitation/misfire it seems to come back every so often. Im sure it is something to do with hot air or when the engine gets hot. Today on the way to QST for some essentials the car was superb a lot better than with the cone filter on (just put the original air box back). It was boosting fantastic and driving a lot better. On the way back it was the same fantastic but after gettin stuck behind a lorry and a lot of stop startin and getting stuck at the lights the temp gauge rose to 90 when it usually runs at about 50-60. I know 90 is usual running temp. I decided off the lights i would boot it up the straight as u do and guess what hesitations and misfire. Only done it the once after sitting in that traffic. What could it be? Injectors? or do u think its the hot air making the intake temps to high? Anybody else ever experienced this? Thanks for your help

[Ski]

faulty/dirty MAF ?

[stevieyid]

I cleaned the MAF about 2 weeks ago. When i put the air box back the mesh did look dirty so i might clean it again. Also would it not affect it all the time not just when it seems to get hot?

[Bowlerwell]

My misfire was due to a faulty POS channel.
Apparently that's common for an intermittant misfire.
These things get hot, and should be attached with heatsink compound.
I guess a relatively high ambient temperature under the bonnet could cause one to fault...?

http://www.sjmautotechnik.com/troubl...4_Ignition.htm tells you how to check if it's the POS or not... but you can only check if it's actually misfiring at the time...

JB

[WabTheKing]

my miss fire was spark plugs, they looked ok visually but they were fooked

[stevieyid]

All the spark plugs have only just been changed. Does not seem to do it when the engine temp is running from about 50-80 so could it be injectors or something?

[WabTheKing]

i had another similar prob on a 7A and that was split HT leads but yours is an ABY so cant be that

have you vagcom'd it?

[stevieyid]

not after this time but before iwhen it was happening i took it to MRC for a health and no codes and no boost leaks either. Went on a test run but guess what it did not happen. But then i had not related the problem to the hot running or anything. Also had the coils checked and they seemed to be fine.

[WabTheKing]

maybe they are breaking down when they are getting hot like my HT's were

[4WheelDrifter]

Coil pack or POS?

[stevieyid]

Would the coil's or POS show up any codes on the vag com? The link does not work but i went to there site and read about the s4 engine which i take it is the same as the aby s2. That sayss heat can cause problems with the POS. How do i check it with the s2 engine?

[Corey]

Would the coil's or POS show up any codes on the vag com? The link does not work but i went to there site and read about the s4 engine which i take it is the same as the aby s2. That sayss heat can cause problems with the POS. How do i check it with the s2 engine?

Failing coil or POS does not show any codes on VAGCOM, sounds temperature related and is affecting the coils or POS and making them break down.
When this misfire occurs does it do it under all driving conditions or just under load?

[stevieyid]

Just under load. Starts to pick up at full boost then it will jolt and misfire. When i had my plugs changed by MRC the spark plugs look as though they had been subjected to extreme temps

[Ian Simmonds]

I think I've just blown a hole in the wastegate diaphram again on mine, it's okay on anything up to about 2/3rd's throttle then the staggering misfire starts...... You've not done the same have you Steve? - Great for the fuel economy though (33mpg)!

Hope the old girl holds together, still got 400 miles + before a visit to the QST Doctor!

[ridgeracer]

coils...