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Registered
Join Date: May 2004
Location: Maryland
Posts: 468
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Thumping popping
sound from my other car. This something that occurred during an adjustment to the fuel mixture from the mechanic. It runs leaner now but on a cold start (on a cold day) the car starts to pop and thump from the engine. I can feel the thumping/popping in my seat. When the car warms up about 5-6 mins it disappears. What is happening!
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02-03-2009, 05:06 PM
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Registered
Join Date: Oct 2005
Location: Capistrano Beach, Ca.
Posts: 7,235
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Sounds like possible backfiring through the intake which is being muffled by the air cleaner. Don't know what kind of car you have but a lean mixture will cause backfire and will typically go away as the car warms up.
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L.J. Recovering Porsche-holic Gave up trying to stay clean Stabilized on a Pelican I.V. drip |
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02-03-2009, 05:21 PM
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Registered
Join Date: Jan 2002
Location: Long Beach CA, the sewer by the sea.
Posts: 37,748
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Time for a new mechanic. Or at least a reversal of what he did ( by he his ownself
 )Yes, how about telling us what model/engine! |
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02-03-2009, 05:25 PM
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Registered
Join Date: May 2004
Location: Maryland
Posts: 468
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The cat converter was removed and so was the air pump. This can cause a backfire but how damaging is it?
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02-03-2009, 05:55 PM
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Registered
Join Date: Jan 2002
Location: Long Beach CA, the sewer by the sea.
Posts: 37,748
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Shouldn't be problem if the air injection holes are plugged.
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02-04-2009, 07:54 AM
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Designer King
Join Date: Mar 2004
Location: Toronto, ON Canada
Posts: 5,499
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If your car has CIS you may find a slight adjustment richer may do it, or you may need to adjust your wur. If you search you will find this is common for CIS engines.
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Paul Yellow 77 Sunroof Coupe/cork interior; 3.2L SS '80 engine/10.3:1/No O2; Carrera Tensioners; 11 Blade Fan; Turbo tie rods; Bilstein B6; 28 tube Cooler; SSI, Dansk; MSD/Blaster; 16x7" Fuchs/205/50 Firestone Firehawk Indy 500s; PCA/UCR, MID9 Never leave well enough alone |
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02-04-2009, 08:14 AM
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Slumlord
Join Date: May 2001
Location: Canada
Posts: 4,983
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Sounds like a lean start condition. What made the mechanic want to adjust the fuel mixture and how did he assess the results? By ear, fuel pressure, or did he have an O2 sniffer?
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84 Cab - sold! 89 Cab - not quite done 90C4 - winter beater |
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02-04-2009, 08:18 AM
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