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1992 Grand Prix SE 3.1 starting/idling issues.

Borch1965

Borch1965

New member
Hey everyone

New to this site and looking for help. Within the last 2 weeks my Grand Prix started acting up and it has me frustrated. When going to start it will fire and for a brief second, then drop down to idle and will just stall out. I can get it to stay running if I hold throttle open a little and let it warm, once warm she'll idle but will run its idle all the way to 2100 rpm and then drop down to 900 and back again. It will stall if in gear unless I ride the throttle. I checked the codes and these are what flashed, 23,33,34,and 35. I have replaced the TPS, Idle Air Motor, and MAP sensor plus cleaned the EGR valves to no avail. At wits end and need help.
 


I am having almost the Exact same problem... It acts like the car thinks it is cold all the time to me. Will let you know if I figure it out if you like...
 
Your motor probably has a very easy to access valve on the fuel rail to check the fuel pressure, you can probably rent a fuel pressure tester kit from your local parts store. Atleast you could rule out fuel delivery as a problem
 
After extensive looking and a week at the mechanics. We think we have it figured out. The number 3 fuel injector is shorting out at start up. Which in turn screws up the computer and sends false codes. Every sensor has been replaced and double checked. Unfortunatly unable at this time I cannot afford to change out injector, cost to much to find the problem, so I have to wait. LOL. On a side note, while blue is down, went and picked up a 1999 Grand Prix SE as a replacement. Kinda liking this one more than blue.
 


I fixed the issue that I had with my '90 GP LE, so I figure the fix might solve your issue as well. On the drivers side, between the engine and fire wall, there is a sensor with a single green wire right under the throttle body. Un-plug that sensor, and see what happens.
 
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