coughing, sputtering... full throttle...

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Jan 14, 2009 | 10:19 PM

Soul TKR

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From: San Diego, CA

coughing, sputtering... full throttle...

hey guys... just had some 36lb F.A.S.T. injectors installed, and had it tuned with a pretty much flat table 13.1 A/F across the board...

every once in a while when I get on the throttle and I'm in the upper RPM range, the car will cough, or sputter...

any ideas?

I'm gonna pull some spark plugs and see what they look like... i figure that's a good place to start...

any other theories, or anyone with this same issue?

Jan 15, 2009 | 04:21 AM

ringram

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From: Sunny London, UK

Without a wideband and/or scanner you wont get much idea. Could just be a dodgy plug lead. Good idea on the plugs, but unless it does it all the time that might not show up either.

Jan 15, 2009 | 11:47 AM

tkimrey

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From: Oklahoma

Mine was missing a lot a while back and I checked everything: injectors, filter, fuel pump, pushrods, rocker arms, valve springs and couldn't find the problem (including the plugs, changed them 3 times). The problem was, well the only thing I can come up with, was the type of plug I was using. I changed to a different plug and haven't had a problem since.

Jan 15, 2009 | 11:56 AM

ilovemywhitepony

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My buddys car is doing the same thing and its his fuel pump going out. Very rare case cuz Ive always heard of them going out just all of a sudden. Get a fuel pressure gauge and see wut its runnin

Jan 15, 2009 | 02:03 PM

Soul TKR

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From: San Diego, CA

Quote:

Originally Posted by ringram

Without a wideband and/or scanner you wont get much idea. Could just be a dodgy plug lead. Good idea on the plugs, but unless it does it all the time that might not show up either.

Quote:

Originally Posted by tkimrey

yea i've got some NGK TR55 Xi plugs that only have around 3,000 miles on them...

Quote:

Originally Posted by ilovemywhitepony

My buddys car is doing the same thing and its his fuel pump going out. Very rare case cuz Ive always heard of them going out just all of a sudden. Get a fuel pressure gauge and see wut its runnin

I've got a cobalt series autometer fuel guage... just need to hook up the sending unit for it... what's the fuel pressure supposed to be at? and does it fluctuate when on the throttle? what would be a tell tell sign of the pump going out?

Jan 15, 2009 | 02:14 PM

Cole Train

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From: MN

i would guess loose plug wire. My Vette did that when a plug wire came loose. I got on the gas and it was all of the sudden missin' under load. So i hooked it up to my scanner and came up as the #7 cylinder. Then i started to worry as the LS1's are notorious for #7 issues when modded

So i went home, went and grabbed my plug socket and ratcher and pulled the plug wire and it was barely on

lol stupid me must not have snapped it on far enough. Check those connections first is my suggestion

Jan 15, 2009 | 07:07 PM

Soul TKR

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From: San Diego, CA

checked the plug wires... they all seem to be ok

I'll be pulling the plugs this weekend... I noticed while looking that the plugs will be a hell of a lot easier to pull out this time around since i have no EGR and AIR anymore...