High idle cold start --sorry

[glockworks21]

sharing a few pics. Ive cleaned up a lot in the engine bay. I know there are still things not right. I dont know the quality of work that was done over the years but there were a lot of things routed wrong. I still think there are. If anyone sees anything obvious please share. fuel lines are my next step. Thanks for all your guys help. All new to me.

[glockworks21]

Yeah definitely just test the microswitch.
.no need to just start throwing parts on it and hope you fix the problem.

You may want to crack the idle computer case (unless it's new) and look at the board. When my idle computer went bad, I was easily able to see a burnt path. That's not to say a bad one will have a visible clue. The only real way to test one is swap it with a known good one but you might "get lucky".

Ok thanks. I will look !

[82DMC12]

sharing a few pics. Ive cleaned up a lot in the engine bay. I know there are still things not right. I dont know the quality of work that was done over the years but there were a lot of things routed wrong. I still think there are. If anyone sees anything obvious please share. fuel lines are my next step. Thanks for all your guys help. All new to me.

Looks pretty nice overall. You really need to replace all of the fuel lines though, they are original-style and can spontaneous start to leak and start a fire. There are 13 fuel lines between the fuel filter and fuel return including all the injector hoses, cold start, frequency valve, and control pressure regulator. Then there are two flexible lines on the fuel accumulator that have to be replaced, and the two flexible lines on the fuel pump unless you've already updated to the modern GM-style fuel pump. Really can't recommend using the car without replacing all these lines at this point in that car's life. Too risky.

[glockworks21]

Looks pretty nice overall. You really need to replace all of the fuel lines though, they are original-style and can spontaneous start to leak and start a fire. There are 13 fuel lines between the fuel filter and fuel return including all the injector hoses, cold start, frequency valve, and control pressure regulator. Then there are two flexible lines on the fuel accumulator that have to be replaced, and the two flexible lines on the fuel pump unless you've already updated to the modern GM-style fuel pump. Really can't recommend using the car without replacing all these lines at this point in that car's life. Too risky.

started it and jumped to 2k rpm. I immediately pulled the connector off the idle speed regulator motor and it instantly dropped to 900 rpms and stayed there. When i plugged it back in it spiked for a minute and dropped back down. I believe its the original one. Do you think its bad ? or is it just a gremlin chase?

Thanks,

Dave

[Michael]

started it and jumped to 2k rpm. I immediately pulled the connector off the idle speed regulator motor and it instantly dropped to 900 rpms and stayed there. When i plugged it back in it spiked for a minute and dropped back down. I believe its the original one. Do you think its bad ? or is it just a gremlin chase?

Thanks,

Dave

I'm not 100% sure but I believe there is a way to test those on the car. Pull the ISM (leave it connected to the plug of course) and watch the valve opening when the ignition is turned on. I think it opens fully then closes? I will have to search it.

[Bitsyncmaster]

started it and jumped to 2k rpm. I immediately pulled the connector off the idle speed regulator motor and it instantly dropped to 900 rpms and stayed there. When i plugged it back in it spiked for a minute and dropped back down. I believe its the original one. Do you think its bad ? or is it just a gremlin chase?

Thanks,

Dave

There is no return spring in the idle motor so pulling the connector should not make it change. Maybe you have a marginal connection on the connector. Next test would be to move the wires (sideways, pull, push) when high idle to verify bad or good connections.

[Michael]

This thread may help. +1 on the connection. If you pulled the plug, the idle would probably reamain high or rise, not fall.

https://dmctalk.org/showthread.php?1...test-procedure

[glockworks21]

There is no return spring in the idle motor so pulling the connector should not make it change. Maybe you have a marginal connection on the connector. Next test would be to move the wires (sideways, pull, push) when high idle to verify bad or good connections.

I tried that with no change. I took out the idle motor and cleaned/oiled it. i jumped it to test its working and it clicks open and closed. I removed the micro switch and its checked it with multimeter. it works as well. I disconnected the plug on the cpu behind drivers seat- one closest to center of car and the idle spiked up like the other tread said it would. when i disconnect the other clip on that computer it did nothing.

after all that it still jumped to about 2k this morning during cold start. and i can still disconnect the idle motor and it drops immediately.
idk
pretty sure this is original

[glockworks21]

ok.. so the valve isnt closing after 30 seconds or so. the motor hums and it closes about a 1/4 of the way. i put a screwdriver in there to see if i could move it and can feel it vibrating. Ive left it for a few minutes and it has yet to close. Im just going to order a new one unless someone has another idea.
Im guessing the motor is gradually burning out.
I really appreciate all everyones help.



Thanks again.
dave

[Rich]

Do you want to verify the idle speed motor is dead/dying and/or give it a couple of more cleanings? Verify the wiring is OK in any case. A new ISM won't fix that.

This ISM test is taken from another thread on the ISM, which lists other handy elec tests for this device and the wiring:

Another way to test the idle air motor is to measure the resistance with your multimeter. A good motor should read +/-20 ohms resistance between any two pins that are next to each other and +/-40 ohms resistance between the two outside pins.

The idle air motor can be cleaned out if it is not too damaged. The most common way to do this is to detach the motor from the car and spray it out with carb cleaner. Fill the motor with carb cleaner and plug both openings in it. Shake it up and roll it back and forth in between your hands like you are making a ‘snake’ out of clay. You should hear it clicking back and forth. Repeat the cleaning process several times, drain the motor, and then allow it to dry for an hour or so.