UR quattrro misfire

[audinut]

ok i didnt have time to get the bore scope out , the lifters go up and down with the engine turning , they kinda feel/seem the same , it was blowing blue smoke when it came in

its definately a burnt out or bent valve as i cant see it being melted rings or a hole in the piston

[LSG]

Can you do a leak down test. ? Do you have a tester or would you like me to pop one over to you. Also has the cylinder been bore washed ? This could also give you low / no compression.

[audinut]

yea good plan and thanks for the offer , im pretty sure theres a leak down kit in the workshop

i would have thought a washed bore would still give me a small reading ?

[Ian Simmonds]

Ours, about 15 years ago, had loss of compression and it turned out to be a slipped valve seat partially holding the valve open.

[chezz]

maybe a valve collet has slipped and jammed the valve...take the cam out - you don't need to remove the head to do this and examine the valve /spring/followers ...something physically has to be causing this problem.

[stocious]

Get some compressed air in the cylinder if nothing is visually apparent and have a listen. It should be a loud leak if zero compression .

[adam g]

Hmm, blue smoke could mean holed piston or head gasket gone. Agree a hole in piston is unlikely unless it is tuned or modified ecu.

[audinut]

compression test results

cylinder 1 - 100 , cylinder 2 - 95 , cylinder 3 - 75 , cylinder 4 - 35 , cylinder 5 - 0

headgasket anyone?

[s2driveruk]

thats odd...the compression test shows consistent leakdowns from 1-5...not sure i've ever seen that before?

[Ian Simmonds]

Almost as if the head hasn't been screwed down properly one end...

[audinut]

mmm I know , if you want me to make it even more odd , how about this it was stored for 7 years , current owner bought it and took it to dialynx who replaced the fuel system there advice was to drive it once a week , he hasn't and has just stored it and occasionally started it .

the other day when he collected it he said it started fine and drove with no misfire for at least 15-20 mins (he thought he had a fuel issue as it had been in the tank for so long) he then said it started messing around after that.

so from no misfire to the compression readings I have now

[s2driveruk]

yeah exactly, normally you have a few at very similar pressures and one or more fluctuations. Like that as you say Ian, looks like its not on properly.

[Ian Simmonds]

Just a thought, but after 20 minutes the whole block/head etc will have expanded and be hot. Maybe it was seven years of stone cold inactivity followed by this heat cycle that's freed up the head studs.

[stocious]

compression test results

cylinder 1 - 100 , cylinder 2 - 95 , cylinder 3 - 75 , cylinder 4 - 35 , cylinder 5 - 0

headgasket anyone?

what happens when a wet test is done, just out of interest ? looks like there something to be learned fro this, thanks for posting comp results ect..

just had thought, does the oil stink of petrol by any chance ?

[audinut]

just had thought, does the oil stink of petrol by any chance ?

i havent had a chance to check but i will tomorrow