GC001 Posted February 9, 2016 Report Share Posted February 9, 2016 2002 Lupo 1.4 16v (BBY)hiive a misfire on my girlfriends Lupo that I cannot get to the bottom of.it starts fine, and idles fire but one warm when driving when it's not under load it's misfires/hunts quite badly on partial throttle.its had a full service, throttle body cleaned and reset on VCDS, new coil packs and sparkplugs and all vacumn pipes checked.also replaced a leaking section of exhaust.A scan showed up 17961 Barometric/Manifold Pressure SignalsP1553 - 35-10 - implausible Correlation - intermittentThis was cleared and hasn't returned, yet the misfire is quickly getting worse. Done a compression test this morning, and got an almost identical 250 PSI off 3 cylinders, after repeating the test many times; but the cylinder next to the cambelt only managed 225 PSI after testing time and time again.any suggestions what I can check? (I've got VCDS) Quote Link to comment Share on other sites More sharing options...
Pete Posted February 9, 2016 Report Share Posted February 9, 2016 Is it burning oil? My guess is piston rings on cylinder 1. When cold it's not so noticeable, but once up to temperature and the metal expands it becomes more evident, so you start losing compression and there's your misfire. It's not uncommon on the 1.4 16v. How many miles has it done? Quote Link to comment Share on other sites More sharing options...
GC001 Posted February 9, 2016 Author Report Share Posted February 9, 2016 It's done 81k, but doesn't use any oil. Looking down to the cylinders through the spark plug holes does show a lot of carbon build up. Quote Link to comment Share on other sites More sharing options...
Sausage Posted February 9, 2016 Report Share Posted February 9, 2016 Take the plugs out after a run and compare. is the water pressurising as it could be head gasket? other things it could be are valve seats, inlet manifold leak. And just as a precaution you might want to check the cambelt tension as the tensioners seem to be made of chocolate. Quote Link to comment Share on other sites More sharing options...
carrera-gt Posted February 9, 2016 Report Share Posted February 9, 2016 You don't mention the leads as being replaced, did you replace them. ? Sounds like ignitionj, If it's getting worse then something is obviously failing. One other thing is check the leads are correctly routed it might be crosstalk. If you have VCDS you can check the lamda sensor output, mixture might be weak on part throttle but not enough to throw a code. Quote Link to comment Share on other sites More sharing options...
GC001 Posted February 10, 2016 Author Report Share Posted February 10, 2016 It's got seperate coil packs rather than plug leads. i'll use VCDS and check the Lambda sensors, MAF and also cambelt tension. a can of brake cleaner sprayed around the inlet manifold may show up a leak if the revs change. Quote Link to comment Share on other sites More sharing options...
GC001 Posted February 14, 2016 Author Report Share Posted February 14, 2016 (edited) VCDS readings on the Lamba sensor number 2 show 0.820 or there abouts when hot at idle. fluctuates between 0.000 and 0.850 when driving. Edited February 14, 2016 by GC001 Quote Link to comment Share on other sites More sharing options...
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