My 1999 Saturn SC1 began to run extremely sluggish. I pulled over and looked under the car and saw that the catalytic converter(CC) was red hot. I thought it was clogged so I took it to a muffler shop. I actually ran fine on the way there (because it had sat for a day and cooled off I guess). They put it up on the rack while it was still running. As he was telling there was nothing wrong with the CC because the exhaust was coming out fine, the engine began to bog down at idle. The muffler mechanic told me there probably was a sensor problem judging by the symptoms. He did a code check and it was P0300 and p0340: multiple misfire and no signal from camshaft sensor. Problem is, this particular car doesn't have a camshaft sensor. I checked the coils and they were good. I changed the temperature sensor, throttle position sensor and oxygen sensor. I did this knowing that having issues with these things can cause the fuel delivery system to run rich thus causing fuel to be dumped into the CC and igniting. The car will run fine if it sits overnight. After it warms up, the same problem occurs. Is there anything else that I can check that might cause the engine to run rich?
Your cam sensor is in the iginition module. Try cleaning the module off and putting dielectric grease on it to make better contact, it may work. Also check for a vacuum leak and check compression on offending cylinder/s. Check fuel pressure.
October, 16, 2012 AT 7:33 PM
So, would changing spark plugs and wires help also? It's probably been awhile. How do I check compression and fuel pressure?
October, 16, 2012 AT 7:35 PM
You might try that but I dont 'thik it wl fix the problem. You need a compresion gauge and fuelpressure gauge to check. Maybe some adapters for fuelpressure. Auto parts store rent those out.
October, 17, 2012 AT 4:27 PM
This car has no cam sensor the code P0340 0r P0341 is most commonly caused by carbon build up where the spark plug wire meets the plug look for black powder residue arching down the plug etc. Did the exhaust shop perform a back pressure test?If not have them do one because you cant tell for sure if its clogged by feeling the exhaust coming out of the tail pipe. It sure sounds like a plugged cat to me and that will cause a random missfire code but the cam codes set random missfire/cylinder missfire codes as well. Let me know what you find.