I just aquired a car that had some major work done to it recently to rid a random misfire. New heads. That did not cure it fully so they did the cap/rotor...i do not think they replaced the whole opti. There were no engine lights when I picked it up like i saw before, but it still seemed like it was running funny. I can hear a distinct knock everytime the engine cycles it seems. It runs strong some of the time, but other times it shakes and shimmys and studders a little bit. It seems that the SES light begins flashing at a stop after I have been running it good. This is also during a rough idle. At autozone, it came up as a random cylinder misfire. It will flash, then stay solid after that. Anyone have this problem or think of a solution? It has aftermarket ram air and catback exhaust...I think that is it seeing I don't know much about the car. It still runs like a bat out of hell, but just doesnt feel right. The distinct knocking sound is what worries me the most.

 

anyone?

 

come on experts

 

no clue but bump..

 

What year car? I get the random misfire that actually starts out as P0302 then changes to P0300. But my car runs fine and I've replaced most of the basic things that it could be. Other than leaky injectors, I don't think mine is a real problem. I was reading that the 96 OBDII stuff isn't really programmed the best from the factory and their misfire detection is known to give false readings. I've done: plugs, wires, coil, ICM, new headers, new AIR check valves, new EVAP solenoid and vacuum lines, new charcoal cannister, new O2's, new cats. Most of it was stuff I wanted or needed to replace but none of the new parts got rid of my occasional SES light. My idle is steady as can be when the light comes on and it usually only happens at idle speed. So I'm still stumped but I don't really care since my car runs fine.

 

96. It is a very strange problem seeing I have not owned it while it runs good. I cannot tell how bad it is running. Is there something you have to do when you add a ram air system to camaros? Some sort of delete?

 

Anyone know anything about ram air here?

 

Usually the blinking SES light is pinpointing the cylinder with problems. Mine comes up as a P0302 which is cylinder 2 but changes to a P0300. If you can get a scanner to check it right after it happens you might be able to find which cylinder it is before it changes to the P0300. There a lot of things that need to be checked for the P0300 code. Ram air shouldn't have any adverse effect unless there is an air leak after the MAF or something.

 

do you have one of those tools that blink the light as it flows through when you touch a spark plug wire? try that and see if all are working right when you press the throttle, when two of mine didnt, i knew it was the opti and i finally changed it and now its not back firing anymore

 

Ok. I will try that. What is that tool called? Also, could an engine knock cause this? Would the lt4 knock module solve it perhaps?

 

before you go to crazy. check for arching with the engine both cold and hot. i have seen the problem you are describing many times with a burnt or even just a small frey or crack in the shielding of a wire.

 

Be more descriptive. Where? Did you see the part about the knock too?