Help! Diagnosing possible Missfire / coil pack AGU/ 00 engine.

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A7mag3ddon

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Please could someone help me diagnose a miss fire, having read the other threads on possible misfires mine isnt the same symptoms.

Driving normally not above 3,000 revs and not accelerating very hard by that i mean foot to the floor max boosting, car drives and feels perfectly normal.

If i drive down the motor way and put my foot to the floor, once it gets over 2.5/ 3K revs the engine just looses boost, however ive noticed if i lift my foot gently off the pedal just slightly it picks up and can floor it again no problem, i can get it to do this every single time so is a repeatable fault.

When i checked on VCDS i had a 00561 - Mixture Adaptation 14-00 Adaptation limit ( Add ) Exceeded message. I cleared the fault and went back to create the symptoms again for about 20 mins up and down the dual carriage way. Reading back on VCDS shows no new faults.

I was told to check for a miss fire by a friend, using his VCDS on his VW golf MK 5 he can see missfire blocks when i look on my vcds i cant find any measuring blocks ( on his its 15 and 16 ) which shows the Cylinders 1 to 4 and the Missfire Count.

Other thing to note possibly is i changed the alternator about 6 or so weeks ago and had to remove the throttle body housing part a few times ( maybe 4 times ) so i have now ordered a new gasket in case thats damaged although i have used gasket seal temporarily whilst my new one arrives and it didnt seem to get any better.

So whats my next best option?
 
Some early 1.8t don't report a misfire. Example APY / APX don't record this as a fault or by a flashing EML but a misfire will usually make the car shake, you're describing a loss of boost aren't you? What DV do you have, incase it's letting go? Have you checked the boost circuit... clamps etc does it 'sound' like a boost leak?? There are intervention maps, perhaps due to overboosting - but they usually cut the max load for like 10 seconds...
 
I had a similar problem on one of my old S3's. Mine turned out to be a loose wire on the exhaust gas temperature sensor. It also caused the fuel economy to nose dive as it over fuels to help cool the gas temp. Not all S3's have this sensor though, only AMK and BAM I believe.

Other suggestions:
Fouled/damaged/poorly gapped spark plugs
Head gasket/cracked head. This ones extreme and would have other symptoms, smoke, oil mixing with water, loss of coolant but no signs of leak etc.
Large boost leak causing over fueling. I use a carb cleaner and spray the area whilst idling, revs will rise if there is a leak as it will draw the spray in under vacuum.
An unrelated fault causing limp mode, boost will be limited to 5psi. will need to do a scan for fault codes.

You fault code could suggest a large vac leak (from MAF to Turbo inlet) as its hit the additive addaption limit (more fuel required as too much air). Try logging or trending the O2 sontrol sensor to see if that is functioning correctly. I had another strange fault which looked like the O2 sensor wasnt working, turned out to be a duff MAF. If you unplug the MAF and drive it does the fault disappear, if so you could try cleaning/borrowing a MAF before buying a new one. I have a good working spare, if you are anywhere near North Hampshire I could lend you it.

Another fault I had that gave me erratic boost was a partially seized waste gate. I would get full boost or no boost (luckily not so much over boost).

Bit of a mixture there but thats just from my experiences.
 
Did you get this resolved?? If so, what was it?


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