Hello everyone...
My 98 C2500 5.7L Vortex 336,000 miles. There is a popping sound like a backfire heard. This just started about 7 days ago, I did not do any new work on the truck prior to this happening. Here is a clip I found what mine is doing...
Thanks
Usmarine0905

 

Distributor cap?wandering spark,worth a look under it

 

 

Well sorry for the long long delay... I replaced the cap and rotor.. it continued. but drove fine. But now it quit and I had it towed, no spark at all. I have replaced all ignition parts and still no start. It cranks but no start....

 

336K miles is a lot of miles. Have you checked the timing? Also, a backfire is more of a popping sound (in my experience), that does not sound like a backfire to me.

 

It is all good, timing s good and spot on. Crank sensor is getting motor oil on it. I clean it and smooth as a babies butt. Running great