ok , so i really do need some good advice. the 1.8t in my bus has been running fine, its been uber reliable and making good power/trq. my turbo exploded last sunday after a air leak caused a massive overspeed on it. a puff of smoke and the turbo was no more. i replaced the split pipe, but since then its developed a rather odd misfire. the misire was present before i took off the old turbo and after the overspeed. its completly random, the boosy gauge goes mad and it sounds like scooby, but if you acclerate it will pull out of it. no obvious split pipes. boost gauge sits at -24 when normal and bounces between 0 to -09 when its playing up. no smoke of any kind. compression test is good and even across all cylinders. i've changed plugs, coilpacks, crank sensor etc. bore scope down on piston tops looks ok, nothgin obvious. the bus is currently running a spare turbo, so i will flash across a map to suit as the old one was a hybrid unit and this is stock. however its only runnign 10 psi, so should be ok. vcds reports misfires across all cylinders (hence my inital icm or crank sensor thought) no other fault code than those related to misfire p0300 items any ideas ? as its all looking rather expensive at this point. right as im due to be away for 2 weekends and a trip to Wales in it.
yes i agree, what worries me is its makes a metallic sound when it misfires. almost like something is broke and rattling around. rocker cover is coming off tomorrow to check for obvious damage and chain etc.
possibly oil starvation issues to the chain tensioner and/or worn shoe bit, the rattly noise could be loose chain and with revs might boost oil pressure enough to get it to pump out? check coilpack wiring as well, its so common VW sell a kit for it (well SEAT do, but it fits VW still )
so tonight i checked the top end, rocker cover off etc. nothing obvious, everything intact that should be. coilpack wiring checked and all good. what i did notice is that on idle when cold the car is asking for 20% more fuel . this indicates a air leak, but i'm dammed if it can find it. when hot it evens out to around 0 or - 1.5% could the vacuum pcv system be at fault maybe a one way valve. anything i can remove and block to prove ? or bypass ? it ran fine for ages on a run, then after boost started playing up. this is why i'm thinking the pcv system aint playing ball. it also tallies with the boost gauge going mental in what is a normal steady state. could a failure of a one way valve cause this ?
has anyone got the offical testing procedure for the MAF.. i have a multimeter etc. so far im yet to test the maf, lambda. still have the issue
Log the MAF group 2 see if any drop outs or spikes, check peak of 120g/s if a 150bhp engine. Or simply run without it see if it improves? edit - Just watched your vid on FB, sounds like its missing all the time and mechanical sounds don't sound good? Can you post the vid on here?
HI GVK, i still remember you nearly trashing my vr6 turbo at Snetterton, i think into a ultima from memory you had him on pace, but not breaks back to my bus, yeah its got a oil pressure issue. i did the timing chain last night as it was of unknown age. sump is currently about to be off, so i can look at the strainer. i was kinda hope that the lack of oil to the tensioner is causing the issue.. it has 0 air leaks, coil packs etc all changed, icm changed, maf reads good. a good crank sensor fitted from my pile of spare parts. let me see if i can link the video to here.
