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MkIV ASZ Uneven Idle (with logs)

150 Views 1 Reply 2 Participants Last post by  northpole
Had an uneven idle (no misfire just hunting up/down 850-950 rpm) for a while on my mk4, did a scan expecting to find a faulty temp sensor as had that before.

The only other symptoms are the odd time there's a drop in power, not quite like limp mode but definitley noticable and usually when on a steep hill.

However, all seems fine other than a (I guess unrelated) ABS error 18261 / P1853 which i'll investigate seperately.

After a bit of searching forums, it seems that it could be related to an injector problem, so I dusted off my VCDS cable and off I went to take a look at some measuring blocks

Logging engine blocks 001 011 and 013 I can see what I believe may be issues, but would be keen to hear thoughts from the pro's, including suggestions on the cause.

IQ seems to spike randomly (as in fields H13 & H22) Additionally, Cylinder 3 is showing positive numbers while 1 2 and 4 are negative.

Extract from log below, can make other logs/measurements if required.

Font Rectangle Parallel Pattern Number
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2 things that can cause this: injector cables ... but that should log an intermittent fault... or worn cam lobes...
the first can be simply fixed by finding the problem and fixing it or replacing the injector cable entirely.. the 2nd well only one option... replacing the camshaft with one with extra hardened lobes. they aren't the cheapest but in most cases they do sort it out for a seriously longtime... but only if you use the specific pd-oil.
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