My gti’s developed a misfire out of nowhere started the car up last week and it was misfiring but seemed to clear as the revs dropped down to normal drove the car thinking all was ok which it seemed it was! Let it warm up like I always do as it went to come on boost and the eml started blinking and it was misfiring got it home scanned it had no eml on but codes for random misfire and p0302 misfire on cylinder two and p0441 which I’ve replaced both canister and n80 valve it goes away and comes back every couple of weeks not bothered it’s never caused and issue, Checked all plugs they looked ok nothing stood out about plug 2 compared the the rest put them back in and the car was fine until the following day it started straight up like always but was misfiring straight away cylinder two again! Swapped the coil to another made no difference then tried swapping the plug again no different both plugs and coils were new 1500 miles ago, it only seems to misfire now on idle not throwing a code but can be seen on cylinder 2 on misfire counter using vcds it does show the odd misfire across the other 3 cylinders individually but that’s very very rare! Cylinder 2 is showing a misfire constant at idle but it drives completely fine until I get home leave it to idle and within minutes the misfire on cylinder 2 is back but the whole time it’s being driven there’s nothing at all on the misfire counter? I was thinking a sh*t injector as it’s always showed a misfire on cylinder 2 since having new plugs and coils anyway but never triggered the eml and wasn’t constant you couldn’t even tell unless looking with vcds sometimes I’d question if the car was even running as it was so smooth! It doesn’t use anymore oil than it should doesn’t smoke at all and it always starts straight up doesn’t hesitate or struggle although it’s always sounded a bit lumpy on cold starts until the revs settle as normal then it’s fine! If it is an injector I’d be replacing all 4 with genuine and walnut blasting the intake valves whilst it’s apart I did check the spark plugs again today and plug 2 seemed to be little wet with fuel compared to the other 3!
Nearly forgot I do have a compression tester coming back tomorrow so I can check!
