I just recently got done porting the plenum and putting some slp runners on. Now the car seems to idle in drive around 400rpm.
I read the tech article on reseting the IAC. So I tried following the instructions but i think somewhere along the line i hosed up. This is what i did and what happened.

- Inserted a paper clip in slots A & B
- Turned on the ignition
- Unpluged the IAC after 30 seconds with ignition on
- Unpluged the EST wire by the heater box
- Removed the paper clip from AL/DL
- Started the motor and adjusted the minimum idle speed to 450rpm in drive
- Shut off the motor

When I turn the motor back on after everything adjusted it will do okey and idle at 600rpm in drive. Like everythings working great. However if i shut off the motor again and atempt to start it, it will idle between 1,500rpm and 2,000rpm. Whenever i try this procedure it does the samething. Am I missing a step or doing it all in the wrong order?

 

it should be:
- Insert a paper clip in slots A & B of ALDL
- Turned on the ignition
- Unpluged the IAC leaving key on (motor should be pulsing)
- Started the motor and adjusted the minimum idle speed to 550rpm in park/neutral
- Shut off the engine
- Removed the paper clip from ALDL

id remove battery negative to clear EST code and redo the procedure.
and retest your idle.
airdeano

 

When you set minimium air,you should set tps at same time to 0.54v.

 

Shouldn't you NEVER start your car with the paperclip in the ALDL?

 

You're supposed to remove that paper clip before you start the engine. I've tried it both ways and that was the only way it worked. If you leave the clip in, it goes into some sort of limp or diagnostic mode and the engine doesn't run right.

 

I wish I could help you but I have a similar problem. Im idling at about 1500-2500, 2500 on start and 1500 when the engine runs warm. I've done the procedure over and over and just can't fix my idle. Wish i could help, hope someone else posts an answer.

 

It may just be a matter of the IAC becoming stuck. It probably either needs to be replaced or cleaned.

 

So I am not suposed to start the motor with the paper clip in the AL/DL? I hope i didnt fry anything.

 

Nah. You didn't hurt anything. I've done that a few times myself and once I pull it out, everything's fine.

 

There is so much confusion over this, it is very important to follow the correct procedure. Someone should put this in the FAQ/Tech section.

The GM service manual states the following:

- Turn ignition to "on"
- Check TPS voltage, adjust to .54 volts +/-.08V
- Turn off ignition
- Insert a paper clip in slots A & B of ALDL (or enter 'Field Service Mode" with a scan tool)
- Turn ignition to on
- Wait for "at least 45 seconds", disconnect IAC.
- Exit field service mode (remove paper clip)
- disconnect timing connector
- Start the motor and adjust the minimum idle speed to 450rpm in park/neutral (you man need to hold the throttle open slightly to maintain idle.)
- Shut off the engine
- Reconnect IAC and EST
-Turn ignition on and recheck TPS and adjust.

Reset IAC:

-depress accelerator pedal slightly
-start and run engine for 5 seconds
- turn engine off for 10 seconds
- Restart and check for proper idle.

And that boys and girls is straight from the Generals mouth.

Now getting a modified TPI car to idle properly at 450 is damn near impossible, so this step will vary car to car even bone stock ones. Adjust this to where the car will idle slowest but not stall. The IAC will usually raise it sufficiently when reconnected. You may need to turn the adj screw several times before the engine idles depending on your set up.

Oh and you can get away without disconnecting the EST, but the book says it should be done.

 

The computer will use the spark timing to regulate the idle as well as the IAC. So you definitely want to disconnect the EST to get the computer completely out of the picture while manually adjusting idle speed.