96 WS6 backfiring on decel while in park after AIR pump install please HELPPP!!!
06-09-2007, 06:33 PM
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96 WS6 backfiring on decel while in park after AIR pump install please HELPPP!!! ok so right heres the deal, i bought a 96 WS6 sometime ago, when i bought it the previous owner was going to install long tube headers so all emissions are removed (IE air pump) but for various financial reasons he had to sell the car. So a year later i get all the AIR equipment, the pump hoses and everything else that came with my car stock as far as the air system is concerned. So after like 3 days of monkeying around with getting all my factory air stuff back in i get everything perfect, fire up the car...........air pump comes on fine.............after a little while air pump shuts off fine............now heres the problem while the air pump is running if i give the car gas in neutral or park is will back fire on the decel (as rpm goes down) about 10 seconds after the air pump shuts off everything is fine, i can rev to 3500 perfectly with no back popping. The car has never done this before, only something that just started immediately after the reinstallation of my factory air equipment..............so does anybody have any idea what i am talking about? anybody familiar with this problem? Input is really appreciated also no check engine codes........thanks-Mike
06-10-2007, 04:36 PM
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ok allow me to simplify if i could, when the air pump is on the car will back fire coming down from a 4000rpm free rev, the moment the air pump shuts off its fine......... 
06-10-2007, 05:01 PM
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The air pump only runs for 2 minutes when the engine is cold. I dont think you should be driving around doing a 4k free rev when the engine is still cold.
When the engine is cold the PCM richens up the a/f mixture untill it warms up, that plus all the extra air in the exhaust from the air pump is gonna cause some nasty backfiring.
When the engine is cold the PCM richens up the a/f mixture untill it warms up, that plus all the extra air in the exhaust from the air pump is gonna cause some nasty backfiring.
06-10-2007, 10:46 PM
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GMRL i do still have the cats, and i acctually let the car run for a while the pump turn off thaen i can shut off the car, fire it back up (the pump comes on as supposed to) and as i said i give it gas and on the come down it does the old snap crackle pop.......its absolutely fine when the pump shuts off....
trans am bandit that is almost where i was tending to lean towards, The car when i bought it from the previous owner had GM motive 4.10s and a borla exhaust, and i know the speedo was calibrated so chances are there might have been a tune, however the pump runs and shuts off fine, i am at a loss, i found that one of my check valves on my exhaust manfoldts was shot and that still chanced nothing, guess its one of those problems thats just annoying rather than a real problem, becouse as said before i allow the car to get well into operating range before i horse on it, just acts a bit quirky when the pump is on, and it almost smells a little extra rich (gassy?) as well, well so far i do appreciate all of your inputs keep them coming is anyone has any idea
trans am bandit that is almost where i was tending to lean towards, The car when i bought it from the previous owner had GM motive 4.10s and a borla exhaust, and i know the speedo was calibrated so chances are there might have been a tune, however the pump runs and shuts off fine, i am at a loss, i found that one of my check valves on my exhaust manfoldts was shot and that still chanced nothing, guess its one of those problems thats just annoying rather than a real problem, becouse as said before i allow the car to get well into operating range before i horse on it, just acts a bit quirky when the pump is on, and it almost smells a little extra rich (gassy?) as well, well so far i do appreciate all of your inputs keep them coming is anyone has any idea
