What should I check next firing or gas?

TRAVIS32

MEMBER
1992 CHEVROLET CAPRICE
173,000 MILES

I have a 92 chevy caprice with 5.7 liter in it and and I have replaced the plugs, wires, rotary button and distributor cap and I still have a sputter in it which it may cut off when taking off or if I press lightly on the gas it may go I was wondering what else could be done or ckecked gas wise or firing wise? Thanks

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KHLOW2008

MECHANIC
41,814 POSTS

Is the Check Engine Light indicating and have you checked for trouble codes?

Symptom indicates possible fault with the TPS or MAF.

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Wednesday, September 19th, 2012 AT 2:45 PM

TRAVIS32

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5 POSTS

No the check engine light is not on but if we unplug a sensor it will appear but when we plug it back in it will go off

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Wednesday, September 19th, 2012 AT 3:01 PM

TRAVIS32

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I have been told my fuel pump regulator or coil pack could be bad also im wondering are those any indications also or and we moved the tps and the car change tunes is that a sign it could be bad?

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Wednesday, September 19th, 2012 AT 3:05 PM

KHLOW2008

MECHANIC
41,814 POSTS

Valve rattling would be a separate problem, mostly due to oil problems but if the valve lifters are not working correctly with excessive noise, that can cause erratic idling and loss of performance.

How did you move the TPS? They are calibrated during installation and if it is the adjustable type, tampering with it can result in wrong signals being transmitted to the engine computer causing idling, startng and performance problems.

Disconnecting it does not really prove anything as the engine computer is programmed to guess the TPS position when signal from it is missing.
When doing diagnostics, guessing does not work. You need to start from possibilities and eliminate them systematically.

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Wednesday, September 19th, 2012 AT 9:04 PM