Originally Posted by HaulinTwinz
Hey guys I'm stumped. I have a 94 5.0 stock motor. Only has cheap CAI. About 177k. I have run Seafoam, switched the air temp sensor, and just replaced the harmonic balancer new and stock. Above about 3000 rpm I get pinging. Have tried 87 to 91 octane with little help. I live in nor Cal. If and the stock h pipe has the cats gutted. Timing is at 10 and pings at 4500 rpm when down at 6°. I'm truly stumped any help would be greatly appreciated. thanks
1. Timing is not correct, maybe from to much slop in the timing chain/gears.
(You did remove the spout to set the timing and put it back in when finished correct?)
2. Possibly the ECU is malfunctioning and advancing the timing to much.
3. The pistons and or heads are carboned up really bad and the carbon is staying hot causing it to pre-ignite the A/F mixture.
4. Possible plug wire cross ignition. Wire as shown below.