roadrunner
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 posted on 2/8/06 at 06:45 PM |
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pinto exhaust wumph
does any one know what my problem is , the car not me .
when killing the ignition on ma indy the engine stops as you would expect , then after a few seconds a wuuumph sound comes from the pipe ,
it only happens after a good thrashing .
please no coments about how to drive steady.
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john_p_b
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| posted on 2/8/06 at 06:57 PM |
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sounds to me like unburnt fuel in the exhaust going up due to the heat?
built a car, built a home, had a family. lost the family, lost the home, still got the car.
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roadrunner
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| posted on 2/8/06 at 07:01 PM |
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i,ve had it tuned and there was no problem of spare fuel , but my manifold pipes vary in length , the shortest being 7" shorter than the
longest.
wondered if this might be the cause.
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Confused but excited.
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| posted on 2/8/06 at 07:19 PM |
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When you find out what causes it, let me know so that I can make mine do it. Sounds a cool.
Tell them about the bent treacle edges!
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roadrunner
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| posted on 2/8/06 at 07:28 PM |
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its sounds alright , but i find myself leaning into the passenger seat in anticepation.
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DIY Si
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| posted on 2/8/06 at 07:31 PM |
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It is, as you geussed, unburnt fuel burning. If you were to do it at night and stand near the exhaust you would also see a nice bue flame! I
only know as my race engined mini does it too. Scares the poo out of people if you switch it off as they walk behind it!
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Doofus
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| posted on 2/8/06 at 10:34 PM |
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I bet you're running carbs. I converted to EFI and it stopped doing it. Carbs will keep on fueling after you've turned the ignition off.
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DIY Si
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| posted on 2/8/06 at 10:41 PM |
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But it's a lot of hassle to remove what can be a quite cool blue flame.
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Dusty
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| posted on 2/8/06 at 11:57 PM |
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Uncle Buck syndrome!
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C10CoryM
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| posted on 3/8/06 at 01:52 AM |
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A "wuumph" is fine, a BANG! is not  .
My camaro used to sometimes fill up the exhaust with fuel fumes. Then when you went to start it the next time the fumes would explode. Sounded like
a cannon going off. Blew apart the baffles in my muffler. Never did figure out exactly why that happened. Big cam overlap and lazy timing (to run
pump gas) mostly I suppose. Idle mix was pretty fat too.
Anyhow, If your car is tuned well and making good numbers I wouldn't worry about it. Just park that side away from the fuel pumps.
"Our watchword evermore shall be: The Maple Leaf Forever!"
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David Jenkins
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| posted on 3/8/06 at 07:21 AM |
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My crossflow used to give a huge bang every time I stopped, whether I'd been thrashing it or not. Couldn't work out why, so decided to
strip off the exhaust wrap in case there was an air leak underneath.
Couldn't find any leak, but the bang stopped! Still don't know why...
David
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MikeRJ
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| posted on 3/8/06 at 08:02 AM |
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quote:
Originally posted by David Jenkins
My crossflow used to give a huge bang every time I stopped, whether I'd been thrashing it or not. Couldn't work out why, so decided to
strip off the exhaust wrap in case there was an air leak underneath.
Couldn't find any leak, but the bang stopped! Still don't know why...
David
Exhaust wrap would exacerbate the problem by making the manifold and silencer run at higher temperatures than otherwise, increasing the chances of
igniting the fuel/air that gets pumped in when you stop the engine.
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