Weird start up issue

[guss23]

I have an 81 auto that sat for 20 years. I got it and flushed the fuel tank, replaced injectors, changed the fuel pump and filter....and now it starts up every time however the rpm jumps to about 2200 for about 20 seconds and then settles down to 800.
How do I get it to start properly?

Jason

[Bitsyncmaster]

First time I heard of this problem. My guess would be to remove the idle motor and flush it with solvent and then 3 in 1 oil.

[DMCMW Dave]

Swap idle ECU and then the idle motor off your other car.

[dmcpilot]

My car does the same thing, but not for 20 seconds. I turn the key and starts right up and it goes up to about 2000 rpm for about 10 seconds and hunts for 850rpm for another 30 seconds and is fine after that.

Raymond
#6219

[DMCMW Dave]

One other test - Start the car and let it go through the gyrations and settle down. WITH THE ENGINE RUNNING reach behind the driver seat and unplug the connector on the idle ECU closest to the center of the car. The engine speed should take off and rev to somewhere between 2000 and 2500 rpm. Plug it back in and the idle should immediatly come back to 775rpm +/- . If unplugging the connector has zero effect, your idle speed control is not working and is either stuck or bypassed.

If it passes this test, the ECU is working, the motor is working, and the motor isn't sticky. If the reactions are anything other than described, or have significant delay (or no effect), start troubleshooting.

BTW - it is not uncommon for a stuck idle speed motor to cause the ECU to fail as well.