backfiring

[Paul Gagnon]

My Dad's '85(I think) Caravan backfires when you let off the gas, especially upshifting under moderate to heavy acceleration. It's really loud, like a gunshot. The van is a 2.2L with a 5 speed manual. Any ideas on what is causing the backfiring and how to fix it?

[mike]

First thing I'd check is for exhaust manifold leaks. They're without a doubt the #1 cause of backfiring when letting off the gas. Especially if its JUST when you come off the gas.

[Paul Gagnon]

Thanks I'll check that. It does sound a bit like there is an exhaust leak at the manifold..