Hey guys. Need some help with my girlfriends 98 cobra. She started the other morning and it had a miss. I went out and started it and it felt like a dead cylinder. Shut it off and it wouldnt start again. Lucky for her (not so much for me) I am a GM technition. Have been for 12 years. I checked fuel pressure, cranking it is at 38 psi. Check spark, got spark at all plugs. Have injector pulse on all injectors. Check compression and all comp seems low... 85-75. Thought maybe timimg chain "jumped" pulled front cover to find timimg chain in tact. So here I am scratching my head..... any help would be greatly appriciated.... dont want to get rid of the girlfriend so breaking up with her is out. : )


thanks
Charlie

 

The timing didnt jump, these are zero tolerance engines and it would be much worse if it did. By injector pulse, Im guessing you checked the signal at the harness and not the injector itself. If it starts again one by one pull the harness from each spark plug wire and check for a change in engine response (harness from the COP if coil on plug). If you find one that dosent change you found your dead cylinder. Check the plug to see if your actually getting spark though the plug. If this all checks out, check the injector itself. It could be shorted inside, worn out, clogged, ect.

 

It wont start now. It acts like it is out of time. Is there a crank/cam sensor issue i should look for? Im going to scann it for codes tonight.

 

scan it for codes would defiantly help, if you pull any, post them up and we can help out more. The crank sensor could very well lead to this, but I dont want to lead you into a part swapping fiasco. Hopefully you can get some codes up, or someone will chime in with they're experience.

 

Well I found the problem. After thinking about it overnight, I remembered the Northstar engines doing the same thing with cam sensor issues. So I bought a cam sensor from the dealer. The parts guy gave me two pigtail wires for the connector as well. He said the techs always asked for the wires as well. So I get home and go to pull the sensor out, and found the wire insulation deteriorated and the bare wired contacting each other. So I replaced the wires and the sensor. Fired right up!!!

 

congrats, I'll keep that in mind for next time and should probably check mine, any hint to location?