Engine will not idle

GPGRAHAM

MEMBER
1992 CHEVROLET CAPRICE
5.7L
V8
2WD
AUTOMATIC
151,000 MILES

Engine starts, and runs as long as the throttle is moving. When the throttle is still, whether at idle or at any fixed position, engine hesitates, surges, and eventually dies. MAP tests okay, as does TPS. New fuel pump and filter. New gasket inside throttle body, old one had a small leak. Problem did not change with new gasket. Fuel spray visible when running from both injectors. PCV and all sensors good (including O2). Code 45, intermittently.
Ignition system fine, and engine runs when pouring fuel into throttle body. All vacuum lines good, no leaks.
Cannot drive the car to mechanic or to parts store. New fuel pump is running, with new fuse and relay
Acts like bad TPS, but TPS is fine.

1 Reply

JACOBANDNICKOLAS

MECHANIC
109,867 POSTS

Hi,

The code you have is related to a rich fuel mixture. I realize that the fuel pump is working, but have you checked fuel pressure to make sure it isn't too high?

I have attached a quick diagnostic flow chart related to the code. Take a look through it and let me know if it helps. Also, let me know if you have checked the catalytic converter to make sure it isn't plugged. A rich mixture could have damaged it.

If you look at pic 2, it shows the PCM ground for the O2 sensor. Make sure the ground is in good condition.

Let me know if this helps or if you have other questions.

Take care,
Joe

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