02 Pontiac Sunfire Ignition Enigma

pontiac

#1

My 2.2L OVH Pontiac Sunfire engine wont start on 30% of the keycycles. For the past two months, 70% of the time, turning the key results in start-up, car drives away and runs fine. The other 30% of the time, turning the key to start, it either cranks but won’t start, or starts for 1-2 seconds (if I git it a little gas) and then shuts off. I let the car go to sleep and repeat process and it will repeat the failure. 3rd, 4th and 5th attempt usually results in start-up. I have replaced the crank position sensor, checked fuses and relays, tested the ignition coils with a volt meter, and tested the fuel pressure and everything works. I am also having issues with my instrument cluster (light out and tachometer not working) that may or may not be related. I do not get a security light. Sitting between key-cycles for hours vs minutes seems to increase chance for success. Also, I am not getting any error codes. Any idea of whats going on?


#2

In the no-start condition, either you don’t have spark or you don’t have fuel pressure. Have you checked for spark with an in-line spark tester? And you said you tested fuel pressure, but was it up to spec when the engine wasn’t starting?


#3

The fuel pressure was up to spec in the start and no-start conditions. I have not tested with an in-line spark tester yet. I’ve heard of these symptoms being common with a bad ignition switch, should I replace that next?


#4

I would start by pulling the plugs. Could be as simple as bad plugs. And if plugs are bad they may have damaged the coils even though you say you tested coils. Then do inline spark test. I wouldn’t just assume bad ignition switch.