Low idle/stalling new thread

[Jrgunn5150]

The IAC valve is new and the throttle body looked clean when I shined a light down it

Did you do a relearn when you replaced it? Did it idle low before replacing it?

 

[Trstrugar]

I didn't replace it the guy before me did. It looks brand new. I doubt that he did a re learn, I've never heard of that I thought you just plugged it in.

 

[Jrgunn5150]

2. IAC reset/min idle speed- This sets the throttle plate on the throttle body to a specific rpm. I recommend about 500 rpm for most engines. Procedures- Go to sheet 7 of the pinout diagrams. At the top is the ALDL connector. You need to put a jumper between pins A and B of the connector. These are pins A9(wht/blk) and A12 (blk/wht) on the ECM. This puts the ECM into aldl mode. Turn the key on (not start) and the IAC should drive completely closed. You will normally hear a buzzing from the IAC. If you have the winaldl up and running on your laptop, you should see the IAC went from 145 to 0. Now unplug the IAC connector. turn the key off. Remove jumper. Start motor. If the idle is too low you may have to keep it running. On the front drivers side of the throttle body is the adjustment screw. It may be behind a silver plug. If so just use a nail or punch to poke it and remove it. Then use a #20 torx bit to adjust the idle speed to at least 100 rpm less then your warm idle speed. if 600 then set to 500 rpm. You are looking for the lowest consistant idle your motor will do. When set, turn off motor and reconnect the IAC. I try to keep the IAC count to at least 40 with the motor warm and idling.
This is a good time to verify the operation of the IAC. When the jumper is in and the key is on the IAC is driven closed. So while it is idling to set min rpm put a finger over the IAC port just above the IAC. There should be no air being sucked in and you should be able to see the pintle on the IAC.
When the IAC is connected and operating there should be a small amount of air being sucked in the port at idle and should increase as you apply some throttle.

 

[Trstrugar]

I'm not quite sure I understand that, you jump the terminals of the plug to the valve, or the terminals on the valve itself?

 

[Trstrugar]

Also I had heard that a loose throttle shaft bore can do things like this, but mine seems to be tight. I did however notice that on one of the injectors spraying down the bore, is very faint and uneven compared to the other one. Wondering if this could cause weird idle problems or if the computer would compensate for it

 

[Jrgunn5150]

I'm not quite sure I understand that, you jump the terminals of the plug to the valve, or the terminals on the valve itself?

Jump the pins on the ALDL port beneath the dash.

Also I had heard that a loose throttle shaft bore can do things like this, but mine seems to be tight. I did however notice that on one of the injectors spraying down the bore, is very faint and uneven compared to the other one. Wondering if this could cause weird idle problems or if the computer would compensate for it

It could if it was bad enough

 

[Trstrugar]

Jump the pins on the ALDL port beneath the dash.




It could if it was bad enough

I bought some lucas injector cleaner. Im going to run it through the tank and see if it helps. If not ill just take the injector out and clean it manually. The cover over the manual idle adjustment screw is really on there. I went at it for a little bit with a chisel and hammer and ended up just denting it up real bad but i couldn't get it off. Ill try again tomorrow with a drill.

 

[Trstrugar]

I never did solve this problem, I just have been running it as it is. Still throws a code for running lean. Next step is going to be to try and replace the throttle body. The guy before me rebuilt it himself and I'm not confident he put it together right. Also the connector for the TPS is cracked and moves a little freely. Don't know if this could cause loping idling and low idle in drive.

 

[Jrgunn5150]

I never did solve this problem, I just have been running it as it is. Still throws a code for running lean. Next step is going to be to try and replace the throttle body. The guy before me rebuilt it himself and I'm not confident he put it together right. Also the connector for the TPS is cracked and moves a little freely. Don't know if this could cause loping idling and low idle in drive.

Very very likely.