2002 996 misfire
#3
Race Director
If a VarioCam actuator or solenoid bad enough this might generate an error code in its own right. In the meantime, it might just generate a misfire.
A misfire in just one cylinder can be a bad injector but engine controller will attempt to adjust/adapt by if injector blocked injecting more fuel in the other cylinders. Long term fuel trim on this bank will reflect any enrichening or leaning (if the bad injector leaking) of the air fuel mixture.
Another source of a misfire can be a burned valve. I've seen this happen on just one valve -- exhaust -- in an engine but if one cylinder can experience a burned valve, two cylinders can.
Adjacent cylinders experiencing the same symptom suggests a common failure between them: intake manifold leak; head gasket leak; or cracked head; porous head or block.
What do long term fuel trims look like?
What did the old plugs look like from these cylinders? Exceptionally clean, dirty, oily, dark with carbon or other deposists; or just normal?
What do the new plugs look like?
And of course the misfire can be an early sign of more serious troubles with the camchain drive. What is engine noise like?
Sincerely,
Macster.
#4
RL Community Team
Rennlist Member
Rennlist Member
When does the misfire and CEL happen? Right at startup? A worn/bad flywheel can result in a misfire and subsequent check engine light a couple seconds after startup.
#5
Hey all, thanks for the reply, the misfire takes up to 5-7 minutes to occur and the CEL light flashes and eventually stays on. I will investigate all these ideas and post again, thanks Ken911