All Things Mk5 > Mk5 General Area
rough idle/misfire without fault code
mjmallia:
Yes and no.
The rings I mentioned gave a lumpy idle that sounded like a misfire, but the car was not misfiring due to a lack of oil pressure to the cam phaser not being able to manage it correctly.
I also had a misfire on cly4 due to carbon build up but still that was not registered as an error code but could see the count and hear it also.
generalen15:
UPDATE! i did check live data on misfires and it misfired alot on cyl 2 and very few on cyl 3 so i tried swaping plugs and coil but with no progress so my only thought was ''well the new services injector must be bad'' on cyl 2 and cyl 3 so i was gonna try to swap them with 2 of my old ones that i know is in working condition but when i remove the intake i notice cyl 2 runner flap was very melted so that must be the problem, so now i just need to order a working manifold and see if the problem will be fixed after that...
ZoliWorks:
--- Quote from: generalen15 on July 11, 2025, 11:35:08 am ---UPDATE! i did check live data on misfires and it misfired alot on cyl 2 and very few on cyl 3 so i tried swaping plugs and coil but with no progress so my only thought was ''well the new services injector must be bad'' on cyl 2 and cyl 3 so i was gonna try to swap them with 2 of my old ones that i know is in working condition but when i remove the intake i notice cyl 2 runner flap was very melted so that must be the problem, so now i just need to order a working manifold and see if the problem will be fixed after that...
--- End quote ---
Honestly at this point just get one of those ebay/aliexpress runner flap delete kits and re-map your car for an RF delete. If you dont remap, you'll have cold start misfires.
Good thing you caught it in time tho. If the engine sucked it in, it would have been very bad.
Still, I would do a compression and leakdown test on that specific cylinder. I have a hard time accepting that only cyl 2 got melted while the rest look fine. Maybe a valve isnt closing properly and exhaust gasses bypass back into the intake? Or worn out/pitted camshaft lobes are messing with the valve making it not seal properly.
generalen15:
--- Quote from: ZoliWorks on July 11, 2025, 12:07:39 pm ---
--- Quote from: generalen15 on July 11, 2025, 11:35:08 am ---UPDATE! i did check live data on misfires and it misfired alot on cyl 2 and very few on cyl 3 so i tried swaping plugs and coil but with no progress so my only thought was ''well the new services injector must be bad'' on cyl 2 and cyl 3 so i was gonna try to swap them with 2 of my old ones that i know is in working condition but when i remove the intake i notice cyl 2 runner flap was very melted so that must be the problem, so now i just need to order a working manifold and see if the problem will be fixed after that...
Honestly at this point just get one of those ebay/aliexpress runner flap delete kits and re-map your car for an RF delete. If you dont remap, you'll have cold start misfires.
Good thing you caught it in time tho. If the engine sucked it in, it would have been very bad.
Still, I would do a compression and leakdown test on that specific cylinder. I have a hard time accepting that only cyl 2 got melted while the rest look fine. Maybe a valve isnt closing properly and exhaust gasses bypass back into the intake? Or worn out/pitted camshaft lobes are messing with the valve making it not seal properly.
--- End quote ---
yes, the plan is to check the compression and build up on cyl 2 and i will do flap delete on the other intake that i will buy. maybe a dumb question ticking lifter on these engines cant cause exhaust gases in intake right? cause i have 1 or 2 ticking lifter that im was gonna take care of in like 2-3 weeks when my colleague is back at work, and i can mention that the day all this happend i was crusing at 160kmh and the car started misfire like crazy on cyl 2 and i had to drive for like 5-10 min at 80 kmh behind a truck until nearest truckstop, couldnt that overheat and melt the plastic?
--- End quote ---
hcmzah:
what causes these to melt, does anyone know?
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