Another IAC Question!

Slo5Oh89 said:

I reset the KAM ran it again got proably 20 miles on it and still surging with new IAC. Just for a shot I put the old one on again idle was fine still just under 1K. Did I just get a bad IAC and let me guess I should of gotten the Ford replacment part huh?

I also did bump the idle up some with the new IAC over 600. Once again I do want to say I just had the upper intake off a last weekend. Not sure if that helps or not.

Click to expand...

When you set the base idle, the IAC needs to be unpluged. So did you set the idle to 600 with the IAC hooked up?

If you run a KOER code test and the RPMS raise, then the IAC is doing its job, and the base idle just needs adjustment.

Follow this and see how it acts afterward

1. Clean TB with carb cleaner and nylon brush (toothbrush size). Engine off, fully open TB blade and spray/brush TB until all gunk and oil residue is cleaned.

2. Allow to dry, or close TB blade and start engine until it clears all carb cleaner fumes/liquid.

3. Let engine idle...if it doesn't, increase idle speed via TB stop screw until engine stays idling on its own.

4. Disconnect IAC valve, if engine dies repeat 3 with IAC disconnected.

5. Set idle speed to the lowest setting possible between 650-850 rpms with IAC disconnected. It is key to use the lowest possible to prevent idle surge, rolling, etc once the IAC is connected as follows.

6. Turn engine off, and reconnect IAC

7. With Ign On Eng Off, check TPS voltage output....if it's between .8vdc - 1.0vdc, it's OK. This voltage check should be done between the Green and Black wires at the TPS side connector as shown in the pic below....(-) terminal of the DVOM on the Black wire and (+) terminal on the Green wire.




8. Disconnect battery (-) for 3-4 minutes.

9. Reconnect battery, start engine, allow it to idle for 2-4 minutes to confirm setup,

10. If idle speed falls too low or stalls, increase idle speed via the TB set screw a little at a time.

11. Turn engine off for 20 seconds, re-start engine and repeat 9 - 11 if required.

12. Reconfirm TPS output is within the .8vdc - 1.0vdc range.......you're done!...

..no need to reset ECM KAM (reset computer) b/c the TPS minimum value used for idle control, is automatically reset by the EEC-IV every time the ign is cycled on-off for 20 seconds-on, and as explained in the next post

13. Allow a 10-20 minute "relearning" period under normal driving conditions (drive cycle).....now you're done.


This is a copy and paste.

^^

One note of caution (it's something I feel Joe would have said if he had the time to type up a reply): I would not use Carb cleaner on the TB just in case the coating is still in place. TB cleaner works almost as well anyhow.

And to stress the point, in my experience (as well), one must have the base idle (no IAC function) set as low as possible. The commanded idle is 670-ish and the EEC has a lot easier time adding IAC DC to increase the idle speed than it does trying to lower the physical idle (to try and achieve the commanded idle).

Posted via Mobile Device

My bad on the carb cleaner step. That's usually one step that I skip over, since most cars that I work on are fairly clean, and with aftermarket Throttle body's.

Slo5Oh89 said:

Once again thanks guys. I did set the idle with the IAC hooked up! I know there are 2 screws on the TB sensor what one do I use for adjustments? And what is a KOER Test? I really think that setting the idle with it unhooked will help thought you had to have it plugged in for engine to run. I will run through this check list this weekend.

Click to expand...

You want to know which screw to adjust the idle with? Or the TPS voltage?

The idle is adjusted with the screw on the back of the throttle body, facing the firewall. Down where the throttle cable attaches.

The KOER test is when you dump the computer codes while the engine is running. "Key On, Engine Running".

The engine will should idle fine with the IAC unhooked, get the engine up to operating temp first.

Slo5Oh89 said:

I got it to where it will idle good from cold to operationg temp, with the IAC. Is running accessorys such as the front window defroster, A/C, at idle a learning process with computer to. When you run one of them it almost dies, then the idle will surge a little after you turn the accessory off. Then if you turn the key off and start it again idle is great. Any ideas or just drive it a while and it will go away?

Click to expand...

Something you can try if you like is to let it idle for a couple of minutes with no load. Then shut if off, wait a few minutes and restart it with a load of accessories. Let it idle for a few minutes in this capacity.