popcorn noise

[tonynut]

I have a 95 Lumina. When I accelerate there is this noise just like a popcorn popper coming from somewhere. Once it gets through the gears it runs smooth and quiet. If you accelerate very slowly the popping is less but the harder that you press the pedal the louder and faster the popping. Help - I feel like I should be adding butter and salt somewhere!

[itzed]

Could be pre-ignition, detonation, or what most people just call "knocking". Usually caused by carbon build up in the combustion chambers which retain heat and cause an explosion before the spark plug fires. Is it worse going up hills? Does it get better or go away when you use premium fuel?

[richtazz]

I agree with itzed, it sounds like detonation. Try premium fuel next fillup, and add a good fuel injector cleaner too. If the sound goes away, you've got carbon buildup on the piston tops that is causing the air/fuel mixture it ignite as the piston is still on it's way up, before the plug fires.

[tonynut]

so you dont feel that it could have anything to do with the transmission? that is what i have been told by some others but they didnt know what exactly it was.

[corning_d3]

That popping is usually caused by a slipping drive chain. This is not uncommon for these transmissions. The drive chain is around $100, but depending on the subframe, the transmission may have to be removed to change it out. Have someone stand outside the vehicle while you hold the brake in gear and give it gas until it pops and note if the popping is louder on the passenger side or the drivers side. If it's the drivers side, it's more than likely the chain. Don't rule out an axle that is working off the output shaft, though...