Re: Just Guessing
Xjman1 said:
My old '90 did that and it was the Idle Speed Sensor on the throttle body. Replaced it and all was well. Just a guess though as you may have other symptons??
Joe
The Idle speed sensor has several names..
ICA (Ignition Control Actuator) special order from checker, when faulty causes a high idle at like 2000RPMS at start up and will slowly level out.
First clean the throttle body(TB) and ICA sensor with carb cleaner, located next to the TPS on the TB,
Also clean all the connectors.
Id also test your TPS that can cuase the hesitation you describe, simple cleaning often helps..
TPS (Throttle Position Sensor)
special order form checker about $55, can cause hesitation and stalling when retuning to idle, also see EGR is stalling
First clean all connector connections and sensor using Carburetor cleaner and electrical contact cleaners.
TO TEST:Use a multi meter to test the three wires. Orientation of the three wires may differ, but one is a ground, one is 5V source,
and one is .75V DC signal. Do all tests with the engine off and the key in the on position.
First find the ground, put meter on ohms setting, and put one terminal on the clean ground terminal,
the other terminal probe the TPS signal wire. I use T-Taps to tap into the wires so not to hurt the connector. My ground wire showed 15 ohms,
Not great but not TOO bad, Some guys jump this wire to a better ground. Now put your Volt meter on volts setting and
probe your ground on the connector, and look for the 5V source, 4.5V is acceptable. Try with respect to your battery ground also.
Next test your signal for about .75 volts at idle. If it has no voltage at idle its BAD, but if it has the .75 volts, you then need
to slowly move the throttle from idle to open, looking at the voltage to make sure it slowly rises with the
throttle movement upward. If the voltage hops and is not a nice even rise, replace the sensor if cleaning does not help.
