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Car starts and idles, but breaks up BAD!!!

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Old May 24, 2004, 08:21 PM
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Car starts and idles, but breaks up BAD!!!

Alright, I installed my Walbro pump and got the car up and running, ran it for about an hour and the car worked perfect.

Started up later that night, started and idled perfect, but as soon as you gave it gas it started breaking up (sputtering and backfiring, like it was pulling timing)

Thought it was the pump so I put the stock back in. Guess what? The problem still there, It starts and idles perfect, even runs great under - vacuum, but as soon as boost builds it breaks up bad!

Have reset ECU, check for blown IC hoses, and replaced plugs and fuel pump?

NEED TO GET THE CAR BACK ON THE ROAD!
Old May 24, 2004, 08:27 PM
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how much vaccum you pullin at idle? then rev it to 2500 and read the vaccum?
Old May 24, 2004, 08:29 PM
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then sanp the throttle real quick and see what happens, do it a couple times to verify results. then let me know what you see
Old May 24, 2004, 08:30 PM
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-3.5psi up to 4psi at 3000K rpm...no load though
Old May 24, 2004, 08:31 PM
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holding the rpms at 2500 rpm while sitting still how much vaccum, same with idle just sitting there, in/hg measured?
Old May 24, 2004, 08:31 PM
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+ boosts between 2-4psi, but this is sitting at idle. When driving partial throttle boost hits between 6-8psi then breaks up bad! Reading from an E-01.
Old May 24, 2004, 08:33 PM
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Drops back down to -vacuum....where you going with this?
Old May 24, 2004, 08:33 PM
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does the car slowley pull back into vaccum after you let off when snapping it? and does your bost gauge read in inches of mercury?
Old May 24, 2004, 08:35 PM
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your car should have between 17 or so in/hg at idle. 20+ at 2500 rpm
Old May 24, 2004, 08:35 PM
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when you snap the throttle it should go to zero or maybe a few psi then somewhat slowly return to 17.
Old May 24, 2004, 08:36 PM
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Hmm.. sounds like the speed controller for the pump.. at low load it runs slower than high load.. Double check the connectors and make sure its drawing fuel in..

Are you getting alot of black smoke when it happens? a Check Engine light? or what?
Old May 24, 2004, 08:45 PM
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No CEL, no smoke, just falls flat on its face and sputters. Check the connection a couple of times and reinstalled, If I pull it out again I think I will get drain bamage from the fumes!.
Old May 24, 2004, 08:50 PM
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and austin i was just wondering if you didnt melt your cat. my friend melted his cat after installing a pump, his car was runnign extrmely rich and it overheated the cat. im trying to figure a reason why your car would run fine for an hour and then have this problem, changing the pump caused something else to fail. and if changing the pump is all you did. then im just guessin, and that was my first guess, if while holding the engine to 2500 rpm while sitting there if the vacuum does return to what it is at idle or alittle more, id take a look at your cat.
Old May 25, 2004, 11:56 AM
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Originally Posted by projekzero
and austin i was just wondering if you didnt melt your cat. my friend melted his cat after installing a pump, his car was runnign extrmely rich and it overheated the cat. im trying to figure a reason why your car would run fine for an hour and then have this problem, changing the pump caused something else to fail. and if changing the pump is all you did. then im just guessin, and that was my first guess, if while holding the engine to 2500 rpm while sitting there if the vacuum does return to what it is at idle or alittle more, id take a look at your cat.
The vacuum does go negatively past the idle point and then returns to normal idle vacuum. The car is catless with 3" turbo back.
Old May 25, 2004, 11:59 AM
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did the car stutters or something???



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