Mechanics

CHEVY LOSING POWER UNDER LOAD

1997 Chevrolet Suburban

Engine Performance problem
1997 Chevy Suburban V8 Two Wheel Drive Automatic 190000 miles

This is my second engine in this Suburban, another 454 cu in. The first one blew, cracking the block, and this one has maybe 8,000 miles on it.

We've been scratching our head over this problem for some time. The 454-V8 runs fine while the engine is cold, accellerates like a skitterish puppy. But when the engine heats up to anywhere near normal, it starts missing and bucking under load, no codes. The warmer the engine gets, as in on a longer trip, the worse it runs, but it idles fine under hot or cold conditions. Sometimes pumping the gas pedal helps straighten out the bucking while under load, but nothing makes it right.

We've done the distributer, plugs, wires, changed the fuel pump (ouch$) and all to no avail. Any ideas?
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ED GARNIER
May 28, 2010.



Hi ED GARNIER, Welcome to 2carpros and Ty for the donation

Inspect and test all the following listed below and get back with some testing results

Oxygen sensor.
Catalytic converter.
Fuel injectors dirty/sticking.
Mass airflow sensor/Airflow meter.
Throttle position sensor.
Manifold absolute pressure sensor.
EGR Valve
Fuel pressure regulator leaking or defective fuel pump.
False air leakage.
Fuel contamination.
Foul/defective spark plugs.
Open spark plug wires.
Ignition coil/Coil packs defective.
Incorrect ignition timing.
Cap and rotor.

Note: If it doesn't apply disregard.

Rasmataz
May 29, 2010.