1996 GMC Sonoma 2.2l running problem

1996 GMC SONOMA
135,000 MILES • 4 CYL • 2WD • AUTOMATIC
Avatar
BLUESLOVER61
  • MEMBER
  • 2 POSTS
96 Sonoma, running problem. OBD II code 303 - cyl 3 misfire. All plugs are carbon fouled, plugs less than 9 mos old, plug wires brand new. Truck idles rough, check engine light will flash when engine is run hard. Possible guesses are coils not producing enough spark, causing rich running and one of the coils failing casing the cuy 3 misfire. Only other guess was a bad throttle position sensor. Any ideas?
Apr 11, 2009 at 11:28 PM
Advertisement
Avatar
BILLYMAC
  • CERTIFIED EXPERT
  • 2,204 POSTS
hi, you wrote in your post that you had two guesses. did you replace these two parts or not yet? let me know and i will try and help thanks billymac
Apr 12, 2009 at 7:42 PM
Avatar
BLUESLOVER61
  • MEMBER
  • 2 POSTS
Hi -

thanks for the reply. As of yet, I have not tried either the coils OR the throttle pos sensor, as I was hoping for input from the group before I spend any MORE money on this vehicle. As it is, I want to fix this problem and send this truck down the road, replacing it with somethign more reliable.
Apr 13, 2009 at 11:25 AM
Advertisement
Avatar
BILLYMAC
  • CERTIFIED EXPERT
  • 2,204 POSTS
hi yes i would check all the coils with an ohms meter.make sure all are consistant.and check the elec plugs at the coil..not likely a sensor since you have no code for this. however the check eng light flashing at higher rpm.could possibly be a faulty ecm.
Apr 13, 2009 at 3:16 PM