NEED HELP i have a noise that just started and its only when im reving the motor, sounds like firecrackers going off in side of engine. so i had my sister rev it up while i looked to see if any sparks were visibly (broken wires) and none but i did notice that it sounded like the pop was comming from inside the head on the passenger side... any ideas?? and plugs and wires have been changed and i noticed my manifold bolts were loose so i retightend them but still same noise

 

When revving the engine. Only when freewheeling or also under load? Could be either timing(lousy gas) or a vacuum leak.......

 

Preignition caused by bad gas, electronic malfunction or valves not closing properly.

 

i can just sit in the driveway and it runs fine under idle but when i rev just sitting still it starts popping say around 3000 rpm and up and i did have an exhaust leak but i just got done fixing all that hoping it would fix it but no luck so im guessing i need to pull the valve covers????

 

Run a tank of premium gas and see what happens. BTW- what year of vehicle are we talking about?

 

ITS an 05 gmc sierra with the 4.8 and also ive only ran 93 since i bought the truck when it had 40,000 now it has 84,000

 

been meaning to get back with ya, do ya have something like HP tuners with which you can do a road scan and look at the timing table..........

 

i do have hp tuners but i ended up driving out the gas i had in the truck and refilled and and whaaa laa no more popping so im guessing for now it was bad gas but i do have another question and this might be wrong forum. whats a good clutch to have in this vehicle with my 5 speed manual cause mine is slipping and what gears are good for the rear end THANKS

 

Bravo on the gas. Can't help ya with the clutch- I'm Mr Slushie. the might be able to tell ya something over in Drivetrain & Suspension............