On Fri, 27 Jul 2001 srubano@xxxx wrote: > chains. Oh and to answer your question it backfires out the tail > pipe...but not a "bang" more of a hesitation "popping" noise. It This sounds to me more like excessively rich fuel mixture than any sort of internal engine problem - especially since in the absence of abuse the PRV internals almost never go wrong, but the fuel system often does. If the mixture is too rich then unburned fuel will go into the exhaust and burn when it comes into contact with the oxygen in the atmosphere. If you've removed your catalytic converters, the chance of this happening is greatly increased. Not that there's anything wrong with a leakdown/compression test anyway, especially if you already have the equipment... valve timing could cause the problem you're seeing. However if it were a backfire through the intake I would consider it more likely.