OK so ive got this miss..........

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Sep 29, 2005 | 10:12 AM

417 Motorsports

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From: Springfield Mo

OK so ive got this miss..........

And just recently started after i ran some race gass from out track one night. Its real bad when the motor is cold but after letting it run for say 10 mins it clears up and is not near as bad. Ive changed plugs twice and is seems to help but its still there. Now what gets me is that if its cold its got like a dead cylinder it seems but if you bring it just into a little boost it clears up

Now after it gets warm and your driving it at lower speeds it has a intermitent miss but at cruising (2300 RPMs or more) its fine.. no miss clean smooth piulls hard ect....

IM LOST tell me what ya think.

Blake

Sep 29, 2005 | 11:01 AM

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From: Canton, GA

Are you still running GM O2 sensors? Is the fuel leaded or unleaded? If it is leaded, you have likely fouled the sensors and this causes poor running at idle and part throttle. At full throttle, the O2 sensors are left out of the equation, so this is why it clears up under throttle. That's my guess based on the info.

Sep 29, 2005 | 11:54 AM

RealQuick

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From: MA

Sounds like a plug wire/ignition issue. Does it feel down on power?

Sep 29, 2005 | 06:41 PM

417 Motorsports

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From: Springfield Mo

Yes the gas is leaded but when i put it in the o2s were already bad... so after is started to miss and that gas was gone i replaced them... still there changed the plugs... fixed for 3 days then its back.... it really doesnt feel down on power.. but damn it gets on my nerves! if i rip on it it will clear up for the most part but someties pops through the exhaust so im thinkin its spark related and the unburn fuels just hittin the hot manilfds and popin....

let me know your thoughts please

Sep 29, 2005 | 09:19 PM

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Weak valvesprings ?

Sep 30, 2005 | 07:22 AM

RealQuick

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From: MA

Quote:

Originally Posted by 417 Motorsports

it really doesnt feel down on power.. but damn it gets on my nerves! if i rip on it it will clear up for the most part but someties pops through the exhaust so im thinkin its spark related and the unburn fuels just hittin the hot manilfds and popin....

let me know your thoughts please

The same exact symptoms were on my step bro's 5.0 mustang. It ran great for 1.5 years then started popping occasionaly after a hard aceleration. 1 year later I finally get him to the dyno and his A/F turned out to be in the 15's @ WOT. Dont know how it got there, but it did. We richened it up, gained significant power/tq and no more popping. Might be worth checking your A/F again if possile.