A buddy of mine is having a misfire in his stock-engined 2002 Si. A code reader has previously told him an O2 sensor code, cam sensor, and misfire on cylinder #1. We don't know the code numbers though; somebody read it a while ago.

We can smell rich gas coming out of the exhaust, so it seems the cylinder has fuel--we assume the O2 code is a result of the rich mixture. We haven't checked the coils or cam sensors yet but the coils and plus are new, so they would most likely work when tested.

What the car is doing is idling very rough at startup, and is difficult to start without finesse, because of the misfire. It's hard to tell if it's misfiring at higher rpm, it sounds intermitent at higher rpm. When the engine drops back to idle from a revs it won't catch itself and will stall out.

Anybody have suggestions on what to check based on all that?

 

If you are smelling gasoline then you maybe having incomplete combustion which is a result of either fuel injection timing or spark timing. But if your code is telling you misfire on number 1 then you might need to check the spark timing and fuel injector pressure. The K series motors don't have distributers like the B-series, so your cam sensor could be sending bad signals to your computer, which could result in late ignition. What I would do is disconnect that cylinder spark plug and run the engine. If there are no changes then you need to trouble shoot that cylinder by changing out the plugs, wires, etc.

 

we unplugged the coil and there was an obvious difference in the idle and the car would not idle unless you give it throttle.plugs and coils have been replaced. could it just be a faulty cam sensor? and way to test that 100% before buying one?

 

get a multimeter and read the output from that cam sensor. If it's good, then check all the other sensors, MAP sensor, MAF sensor, O2, TPS, and RPM Sensor. It could be that maybe your Vtech is malfunctioning. Variable Valve timing was only met to run at mid to high rpm. If it is ran at low rpm, then it would give you bad idling because it is letting in too much air and such.

 

you also might wanna look for a vaccuum leak for your EGR valve and PVC valve.