Idle issue... Starts at about 1500, then up to around 2500.

[MacinTek]

Okay... new wire harness in, new plugs, wires, cap and rotor in, new fuel lines in, vacuum hoses connected correctly, car finally starts and runs... boy does it run! It starts at around 1500 rpm, the after a few seconds, it climbs to 2300 -2500 rpm. and stays there.

Somewhere during reassembly, I seem to have lost the plug thingy that goes over the fuel mixture adjuster in front of the fuel distributor. Is that a major deal? I covered it with a piece of duct tape until I can replace the rubber plug.

[Jonathan]

That adjustment hole won't cause that high idle. Not 2,000+ RPM anyway. Duct tape is fine for now.

That high of a number can be related to a loose or poor connection on the back of the ECU (the black one) in the tray behind the driver's seat. Specifically look for the connector on the passenger side (if it is laying flat in its designed position). That connector will have four wires in it and two of them (diagonally) will go to the little gadget under the valley referred to as the thermistor. If that little bugger is not plugged in well or some other reason why it isn't getting continuity, it can cause that sort of high idle to get stuck there.

You could also have a number of things a little out of whack on the idle speed microswitches and what not near the throttle spool. If you press it back to the rest position from standing behind the car at the engine bay, OR if snapping the gas gets the idle to come back down, then that first thing I described is NOT your problem. If snapping the gas never helps, then it's likely an electrical connection gone bad and not so much a sticky idle system component.

[DMC5180]

The plug being will cause an unmetered air leak of which you will see a slight rise in rpm, but not 800-1000. A golf tee works good for a temporary plug. Make sure the idle micro switch is being engaged with the throttle closed. Also verify you didn't knock one of the wires off the switch when you were mucking around with things.


Dennis

[MacinTek]

That adjustment hole won't cause that high idle. Not 2,000+ RPM anyway. Duct tape is fine for now.

That high of a number can be related to a loose or poor connection on the back of the ECU (the black one) in the tray behind the driver's seat. Specifically look for the connector on the passenger side (if it is laying flat in its designed position). That connector will have four wires in it and two of them (diagonally) will go to the little gadget under the valley referred to as the thermistor. If that little bugger is not plugged in well or some other reason why it isn't getting continuity, it can cause that sort of high idle to get stuck there.

You could also have a number of things a little out of whack on the idle speed microswitches and what not near the throttle spool. If you press it back to the rest position from standing behind the car at the engine bay, OR if snapping the gas gets the idle to come back down, then that first thing I described is NOT your problem. If snapping the gas never helps, then it's likely an electrical connection gone bad and not so much a sticky idle system component.

Hmm... I did notice that the microswitch wasn't pressed when idle, so I adjusted the upper screw so that is did press the switch when the throttle is closed. Is there a balancing act between the upper and lower adjusting screws?

[DMC5180]

Hmm... I did notice that the microswitch wasn't pressed when idle, so I adjusted the upper screw so that is did press the switch when the throttle is closed. Is there a balancing act between the upper and lower adjusting screws?

Yeah there can be. But for your purposes start with the lower screw backed off the stop. The adjust the upper to trip (click) the switch plus a couple turns. That should get you to a normal 775 ish idle. You can make tweaks to the lower screw once you are warmed up to help iron out idle hunt.


Dennis

[PJ Grady Inc.]

Okay... new wire harness in, new plugs, wires, cap and rotor in, new fuel lines in, vacuum hoses connected correctly, car finally starts and runs... boy does it run! It starts at around 1500 rpm, the after a few seconds, it climbs to 2300 -2500 rpm. and stays there.

Somewhere during reassembly, I seem to have lost the plug thingy that goes over the fuel mixture adjuster in front of the fuel distributor. Is that a major deal? I covered it with a piece of duct tape until I can replace the rubber plug.

If you changed the engine harness it's almost certainly a bad/open connection at the idle thermoswitch under the intake manifold known as the infamous VOD. I've never seen a bad connection directly at the ICU but a bad ICU will cause the same symptoms. Sounds like the connection is suspect or the ICU is bad or both (worst case scenario). Use a circuit tester (Ohm scale) to check for an open circuit at the blk/ylw and blk/slate wires at the ECU plug-in to see if it's the switch connection before doing anything else.
Rob

[Ron]

I noticed you have a thread on the alternator light being on but the battery seems to stay up. That could be a symptom of a shorted rectifier diode (or trio) in the alternator, which would allow AC to get into the system and muck everything up...probably a good idea to resolve that first.

[MacinTek]

As it turns out, the culprit was the turnbuckle between the microswitch (butterfly valves) and the throttle mechanism was either too short or too long (I can't remember that far back (20 minutes) due to rampant drug use in my misspent youth), keeping the butterflies slightly open at idle. Idle is now steady at what appears to 750 to 775.

Now, about that alternator... gawd only knows what's in there. It's an '83 so it probably shipped with a motorola but, I think it got replaced a while back. My father kept terrible records of things as mundane as his car. I'll probably replace it soon since I'm sure it suffered some ill effects when the starter kept shorting out.

Symptoms when it shorted out while I was driving were... tachometer goes nuts, I smelled smoke... stopped car and it wouldn't start... and I was at the smog test station when this went down. 11 months later, I can get it smog'd just in time to pay next year's registration.

[DMC5180]

A photo of the alternator showing the wire connections would help.

[MacinTek]

A photo of the alternator showing the wire connections would help.