a496ws6ta

So I am driving to Kansas City and my SES light is blinking, tripping code P0300: Random/Multiple cylinder misfires...but the car is running perfect. Just changed plugs, wires are fine, new opti, just put in a lt4 hot cam and 1.6 rr's and i have lt headers with true duals...has not been tuned for the cam. Could this be false knock or what? It doesnt bother me since it doesn't seem to affect performance but its just really annoying, and it might even be flipping the fans on and retarding the timing if its putting the engine into limp home mode lol.

Any advice?

Thanks in advance

ArkBird96

From what I have heard, a new cam sometimes throws false misfire codes. I think some people have to raise their misfire detection thresholds in the computer to compensate for a new cam.

LS6427

iTrader: (2)

Make sure none of the spark plug wires are touching or able to bang/rub against the metal exhaust pipe manifolds while your driving. They can give you misfires and SES lights flashing and you really might not feel anything at all. Its pretty subtle sometimes.
If you hit a bump in the road and a wire bangs against a manifold it'll arc and make it misfire slightly.
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a496ws6ta

looked over every wire, no burn marks and no arcing present, i think its just computer stuff...so a tune can change the knock thresholds for the pcm and i wont need to buy the knock module?

LS6427

iTrader: (2)

Yeah, I do remember long ago my tuner said my cam in my 427ci was pretty big (for back then anyway). He said he did something in my PCM so my misfires wouldn't put my SES light on all the time for no reason.

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eseibel67

iTrader: (10)

A blinking SES light warns the driver that the cats could be damaged if you keep on driving it.

If you have cats.

a496ws6ta

no cats, long tubes, true duals...brand new o2 sensors too, its gotta just be from the cam im assuming...

peterock98

iTrader: (25)

My car did the same thing it was caused by a vacume leak on the intake manifold gasket.I changed plugs, wires and O2's and the fix was tightening up the manifold bolts.