What would cause my z28 to spudder and backfire when i give it gas and its warm? When its cold it seems to run just fine.

I also don't have a muffler on it right now

Secondly if i let it idle down to 1000 RPM its a PITA to get it to rev back up to 2 or 3000 and it spudders and backfires

thanks
josh

 

There are sooo many things it could be. First thing and the least exspensive thing would be to check your egr valve. A faulty or stuck valve could cause somewhat the symtoms you are talking about. I have a stuck egr valve right now. It wasnt doing it at WOT but now that it is stuck i can feel the loss in power. It runs like crap under load in the lower rpms. You could have a burnt plug wire, bad plug, and worst a bad opti. Are there any ses lights?


Just the backfiring and loss of power makes me think bad plug wire. I went through the same thing a month ago. Had a wire sitting on my header and my car felt like crap. Also had some random backfires. Not the real loud POS truck type backfire but still pretty loud. They were small cracklin backfires.

 

hmmm.... now that i think about it i almost think i might have forgot to put the spark plug sheilds on.... could that do it? that car has only been ran for 8 miles

this is a recent engine installation

 

I doubt it. Although it could prevent them from arcing. I dont use the shields, just plain rubber boots and mine dont arc. Have you looked for arcing at night under the hood?