Questions and Answers

GMC Pinging Q. Has detonation even at low speed and slight acceleration. Higher octane helps but does not eliminate it. I had the fuel injectors cleaned and it seemed to help a bit. Also replaced the fuel filter. Any idea how to solve?? 1994 GMC 1500 4WD 350 engine 80,000 miles Thanks...

A. Lots of possibilities here! Timing? Needs to be 0 degrees. Follow directions on emissions label under hood. EGR valve? Is it working? It is there to reduce combustion temperatures that would increase the chance of ping. There is also a EGR control solenoid that needs to be checked. Is it overheating? This would also cause ping. Most likely fix is the EGR not working or timing.