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Rpm races when TPS clicks off of idle position, & mild idle hunt.

posted by  eflatdude on  Fri Oct 8 17:06 CST 2004
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--1990, 740gl, 8 valve, no turbo, Regina.--

*Simptoms:
1. Idle has intermittent miss, and hunts(750-900 rpm).

2. Can not accelerate smoothly. Engine speed jumps to 2500-3000 rpm
when TPS clicks off of idle.


*Action done to date:
1. Replaced; fuel pressure regulator(expensive Regina p/n), fuel filter, O2 sensor(titainium), injector seals, rotor, cap, wires, & plugs, vac hoses.

2. Cleaned; IAC valve, flame trap, throttle valve, fuel rail, ECU & ground connections.

3. Checked for; vacuum leaks, electrical continuity and/or voltage to sensors/actuators.

4. Flushed injectors with cleaner, via home-made test rig. Spray patterns
may be questionable.

5. Set throttle valve to specs.


*Tests done:
1. Disconnect Air Temp Sensor- no change.

2. Block IAC- simptoms still there, but less exaggerated.

3.Disconnect O2- simptoms still there, but much less exaggerated.


Would appreciate any help.
This is testing my skills and self esteem.

Regards, Rudy.

Over and out.






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