C4 Tech/Performance L98 Corvette and LT1 Corvette Technical Info, Internal Engine, External Engine

engine bOGS fULL THROTTLE

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Old Jun 12, 2012 | 07:28 PM
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Default engine bOGS fULL THROTTLE

1986 HEY gUYS, YOU ARE SO MUCH HELP TO ME. If I gradually push the pedal, car runs smooth, When I nail it, total bog down ? Please help. Injectors new, plugs good, New cap, rotor, T.P.S, MAF new, IAC new, Full regulator & fuel pump new,

Last edited by lanecarpentry; Jun 12, 2012 at 07:40 PM.
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Old Jun 13, 2012 | 03:05 AM
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Originally Posted by lanecarpentry
1986 HEY gUYS, YOU ARE SO MUCH HELP TO ME. If I gradually push the pedal, car runs smooth, When I nail it, total bog down ? Please help. Injectors new, plugs good, New cap, rotor, T.P.S, MAF new, IAC new, Full regulator & fuel pump new,
hows the fuel filter?
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Old Jun 13, 2012 | 07:42 AM
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fuel filter & pump are new
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Old Jun 13, 2012 | 07:43 AM
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Originally Posted by mistaben
hows the fuel filter?
Fuel filter & pump are new
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Old Jun 13, 2012 | 09:14 AM
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Originally Posted by lanecarpentry
1986 HEY gUYS, YOU ARE SO MUCH HELP TO ME. If I gradually push the pedal, car runs smooth, When I nail it, total bog down ? Please help. Injectors new, plugs good, New cap, rotor, T.P.S, MAF new, IAC new, Full regulator & fuel pump new,
not much help on this, is there?
new stuff does not mean its all working properly. sounds like a fuel delivery issue.

does it miss, sputter, or simply no response? if the throttle is gradually opened to full, same problem? I know the air filter is not blocked, right?

"the book" says tps, maf sensors; fuel pressure; spark plugs and wires, ignition timing. terminal D, ckt 453, of the dist 4 way plug, poor connection or open. on the 91, this is the red/blk wire.
my thoughts are that timing would have to be retarded by 6-8 degress to cause it, not likely, since you have no other issues, but- you need to know.

I would check TPS voltage, from idle to WOT, if it was not checked and set when installed, or even if it was.
incorrect polarity between ign coil and pick up coil can cause "poor performance," so the fsm says.
I would try running with the EST, tan wire from 4 way connector, unplugged. Looking for clues, that's all. there might be an obvious root cause to someone, not to me.

saludos, joe
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Old Jun 13, 2012 | 02:30 PM
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Do you have access to a fuel pressure gauge to see what the actual pressure is?
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Old Jun 13, 2012 | 02:40 PM
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Originally Posted by joe paco
not much help on this, is there?
new stuff does not mean its all working properly. sounds like a fuel delivery issue.

does it miss, sputter, or simply no response? if the throttle is gradually opened to full, same problem? I know the air filter is not blocked, right?

"the book" says tps, maf sensors; fuel pressure; spark plugs and wires, ignition timing. terminal D, ckt 453, of the dist 4 way plug, poor connection or open. on the 91, this is the red/blk wire.
my thoughts are that timing would have to be retarded by 6-8 degress to cause it, not likely, since you have no other issues, but- you need to know.

I would check TPS voltage, from idle to WOT, if it was not checked and set when installed, or even if it was.
incorrect polarity between ign coil and pick up coil can cause "poor performance," so the fsm says.
I would try running with the EST, tan wire from 4 way connector, unplugged. Looking for clues, that's all. there might be an obvious root cause to someone, not to me.

saludos, joe
fuel pressure at the rails measures what?
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Old Jun 13, 2012 | 02:51 PM
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Originally Posted by lanecarpentry
1986 HEY gUYS, YOU ARE SO MUCH HELP TO ME. If I gradually push the pedal, car runs smooth, When I nail it, total bog down ? Please help. Injectors new, plugs good, New cap, rotor, T.P.S, MAF new, IAC new, Full regulator & fuel pump new,
definately sounds fuel related. could be other things if there is more to this story...

is the car all stock?

have you changed the Throttle Body, or the tuning? anything else you can tell us about this... does it do it at all temperatures?
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Old Jun 13, 2012 | 05:38 PM
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I am going to check pressure when it bogs but at idle it is 42 lbs & steady, It holds pressure well overnite
Originally Posted by Paul Ruggeri
Do you have access to a fuel pressure gauge to see what the actual pressure is?
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Old Jun 13, 2012 | 05:42 PM
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It takes about 7 cranks to start, In the am when it sits overnite, when it starts up it idles normal, It will start fine all day, It breaks up when nailed full throttle, if you gradually give it gas, it is fine
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Old Jun 13, 2012 | 05:44 PM
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I have a professional throttle body with bigger injectors, It ran great all last year until it sat for the winter, then it ran bad
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Old Jun 14, 2012 | 12:36 AM
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If you don't have a solution to the problem, stay out of the thread.
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Old Jun 14, 2012 | 03:41 AM
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Originally Posted by lanecarpentry
1986 HEY gUYS, YOU ARE SO MUCH HELP TO ME. If I gradually push the pedal, car runs smooth, When I nail it, total bog down ? Please help. Injectors new, plugs good, New cap, rotor, T.P.S, MAF new, IAC new, Full regulator & fuel pump new,
Mine was similar, was spark plug wires.....

Good Luck!

G
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