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#1
05-05-2005, 12:58 PM
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94 Pontiac Transport, 3.8, 4t60-e. ONLY on first morning start up(every day). Some times runs alittle rougher then normal. 2 volts higher on gage. Will kill engine everytime unless you wait about 3 minutes. Then everything is fine. Runs great. Checked altenator & battery, every ground we could find. Does not drain battery. No check engine light. Cant find any tech bullitins from GM. Havent found bad wiring anywhere. No techs in our area have heard of this. Maybe throttle position sensor or....?
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#2
05-05-2005, 12:58 PM
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94 Pontiac Transport, 3.8, 4t60-e. ONLY on first morning start up(every day). Some times runs alittle rougher then normal. 2 volts higher on gage. Will kill engine everytime unless you wait about 3 minutes. Then everything is fine. Runs great. Checked altenator & battery, every ground we could find. Does not drain battery. No check engine light. Cant find any tech bullitins from GM. Havent found bad wiring anywhere. No techs in our area have heard of this. Maybe throttle position sensor or....?
__________________
If you cant drive from gas pump to gas pump across the map, its not a street car. http://s207.photobucket.com/albums/b...hop/?start=100 |
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#3
05-05-2005, 01:17 PM
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If you have power brakes, perhaps the load on your manifold vacuum is too much for some reason. Try depressing the brake slowly or maybe wait until the system goes into closed loop where the computer would compensate.
Perhaps you have other vacuum leaks, (craked vac hoses, etc), which, together with the brake load, cause the engine to stall? Just thinking out loud... George
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"...out to my ol'55, I pulled away slowly, feeling so holy, god knows i was feeling alive"....written by Tom Wait from the Eagles' Live From The Forum |
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#4
05-05-2005, 01:48 PM
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I'm with george on this one. Sounds like a vacuum leak issue. Once its warmed up and you depress the brake pedal does the rpm change at all? If so I would suspect a bad brake booster. I not look closely inspect all your vacuum lines and hoses for leaks or cracks.
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North Dakotas fastest REAL GTO 10.10 @ 131 MPH in the 1/4 Hoping to get it back together some year. www.jandjrepairandrestoration |
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#5
05-05-2005, 02:21 PM
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Already checked vacuum hoses. But may have missed something. It dies no matter how sneaky you try to depress pedel
 No rpm change after a few minutes. Checked hoses already, but may have missed somthing. Will recheck hoses and eliminate vacuum to booster next. Can only try things for a few minutes in the morning  Thanks
__________________
If you cant drive from gas pump to gas pump across the map, its not a street car. http://s207.photobucket.com/albums/b...hop/?start=100 |
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#6
05-05-2005, 06:15 PM
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Like George said, this is only happening in open loop. Have the checked the readings at the TPS in idle when cold? If there is a dead spot, then causing the vacuum load won't be correctly compensated by the AIC if the TPS isn't correctly reading. Also there are issuses with the EGR controls on these engines. Be sure it isn't stuck open allowing the exhaust to mix in with the cold charge, which again wouldn't be properly compensted in open loop with the vacuum load. As you suggested, take the booster out of the system before the vehicle is started and see what happens.Also have you tried loading the power steering system when it is still cold to see if it compensates for a load that way? Might be worth trying. Usually a booster problem this bad would at least cause some kind of idle fluctuation once warmed up. The sensors can be off just enough to cause a problem like this, and not throw a code. Just random thoughts as it is tough to diagnose with a keyboard.Good luck!
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#7
05-05-2005, 06:54 PM
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Your sure that the battery is good? I had a jeep that would start and run, but as soon as you applied the brake it would shut off, we put a new battery in and it was fine.
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Wanted 1977 Can Am forgotten projects or parts cars, other 73-77 Pontiac A-bodys, also 4-speed setup for 73-77 GTO, Grand Ams, CA e-mail me shubedo1@yahoo.com with info. Buy Sell or Trade -------------------------------------- 
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#8
05-06-2005, 07:17 AM
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You guys nailed it.
 Vacuum hose from secondary vacuum manifold to fuel pressure regulator was collasping at the 90 degree bend. Visibly looked fine, but was 75 percent closed & soft. BTY, thanks for the free pepsi's i got  from 3/25yr GM tech's that could'nt figure it out 
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If you cant drive from gas pump to gas pump across the map, its not a street car. http://s207.photobucket.com/albums/b...hop/?start=100 |
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