QuestionI know this is not your make but the top brass suggested I try another expert because the guy in Plymouth was not responding. The problem is new to me. My first fuel injection system. Maybe you have an idea.
My 88 ply, reliant was running so rough I could not drive it. I checked the codes and it said my automatic idle sensor had a short. I replaced the ais and found the the wire harness was shorted due to heat. Respiced the wires. Then the car idled so high I could not safely drive it. Tried letting it run so the computer could relearn the mix but it never lowered. I rechecked the codes and I still had the asi code coming up, but a new one added to it. The tps--throttle position sensor.I put in a new tps but it changed nothing. The butterfly in the throttle body is fully closed. I can not find any vacuum leaks of any significance--vacuum purge seloid should not cause a racing idle. Can you suggest anything?
AnswerHi Jim,
I would suggest a couple of things to do. First, let's get rid of all the stored fault codes from the SMEC so that you can get a fresh evaluation of what the current status of things is (recall that the codes don't self cancel until 50-100 key cycles, so what you read today may not be up to date). Turn on the headlights, then disconnect the battery, turn off the headlight switch, let the car sit for 5 minutes, then reconnect the battery. That should clear the old codes. Then ask for the codes, to verify there are none remaining. Then run the engine and see what fresh codes are detected.
I would note that the 24 and 25 codes don't say that there is anything wrong with the AIS motor or the TPS, but rather that the circuit has some problem which could also mean wiring, as you already discovered. I would suggest that based on the new readout you do an electrical check on both of the new items you installed, and also check the wiring between each of then and the specific pins of the 60-way
connector at the SMEC.
For the AIS you will find that the pins are # 17,18,19,and 20 for brown trace, yellow/black,gray/red, and violet/black wires, respectively. For the TPS the signal on the central pin of the connector (orange/dark blue) is connected to pin 22, while the signal ground (black/light blue) is on pin 4, and the 5 volt supply (violet/white) is on pin 13. If the pin assignments aren't show on your plug, then just turn the plug with the pins facing you and the short tab "up", and start counting from the upper left corner going across where you will get to pin 20 at the right end of that top row.
So once you verify the codes, and that the wires are all patent to the plug, and that none of the pins are bent, let's see how it runs. I can describe how the motor and sensor should respond to an ohmmeter check if you still aren't getting the idle speed under control (basically on the AIS there should be continuity between the pins on one side of the mid-line, and the other side of the midline of the plug, and no connection across the midline. On the TPS is should be a fixed resistance between the outer pins, and a variable resistance beteen the center pin and either outer pin when you move the throttle lever; and smooth transition across the range.
So let us know what you find.
The idle is computer controlled and note easily reset, so it pretty much has to be the wiring, sensor, or motor.
