I noticed yesterday after work and then again this morning when I start my truck ('05 Silvy w/5.3L) that there is a pop, just once as it turns over and once it gets going everything is fine. I ran a scan with my programmer and have no codes, and the plugs are fairly new, NGK TR6's about 6-7K on them. Was running NOS but last time I had it tuned I had the tuner put the timing back in it in preperation for a timing controller and haven't sprayed it since. I recently went from shorties with cats to long tubes with resonators, my tuner forgot to tune the rear O2's out so I stuck them back in to keep the engine light from coming on. Now, I occasionally get a Catalyst system code, but I just delete it and go on down the road. Should I take the rear O2's back out, are they causing a conflict?

 

could be your starter bendex not disengaging

 

Does it sound like the pop is coming from the exhaust?

 

Yeah, it does. I have a cut out that dumps right under the rear passenger seat and I run around with it open most of the time, that's where it sounds like it is coming from.

 

That's a new one on me. Can you elaborate a little more if you don't mind. The only thing I've ever done with starters is change them and that's all I know.

 

Mine pops at cold startup but mine runs pretty rich then. Just when it first fires then it doesn't do it anymore.