IAC adjuster help!

[MUSTANGJOE]

Tryed installing my IAC adjuster plate but car kept reving high afetr the install. I noticed a smother exhaust note and better throtle response but I removed it. The RPM's stayed at 1000 I tryed to make is go down but no luck. Does anyone have any tricks on getting it adjusted? Are your screws all the way in or all the way out? Thanks guys

 

[Mustang John]

Did you disconnect the battery for a while and then let the ECM re-learn the idle strategy? If not, try it as it "may" help... Worth a try.

 

[MUSTANGJOE]

No I didn't..how do i do this? I install the adjuster and adjust it the most I can then disconnect the battery?

 

[Mustang John]

I'm not an idle strategy expert and I haven't used that plate you have.

But, I would try to adjust the idle down as low as I could (700rpm or so) and keep it running, using the idle screw and probably your new adjuster.

I would also check the TPS voltage and make sure it is just under one volt. Say, .96 or a bit less.

Then, I'd disconnect the battery for around 20 minutes, start it, and let it relearn the idle. There are a few different ways to relearn idle depending on what book you read. Regardless of method, it usually gets it under control within 20 miles of stop and go city driving.

Here is the one I've been using "lately" and it seems to work well...

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Credit: Darrin Tebbe

1. Clear the EEC-IV's idle memory by disconnecting the battery for 20+ minutes.

2. Disconnect the Idle air bypass solonoid

3. Reconnect battery

4. Start engine and set idle speed to desired RPM with stop screw on throttle body (900 rpm works great with E303 or larger cam)

5.Turn off engine and reconnect the air bypass solenoid

*Optional (edit: not in MY opinion) -- set TPS to 0.90 - 0.95 volts (Do not exceed 1.0 volts MAKE SURE!) Use a digital volt meter!

6. Start engine and let it idle for 2 minutes with no accessories on.

7. Turn off engine for two minutes

8. Start engine again and run for 2 minutes with every accessory turned on.

9. Turn engine off again. Your computer should have now re-learned the new idle settings. This procedure assumes that you have a clean IAB valve. If it is carbon-ed up then you may need to remove it and clean it with carburetor cleaner

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Good luck, stable idle can be a painful quest... After my motor build, I could hardly keep mine running at all. I let it learn at almost 900 rpm. After it became stable there with a couple days of driving, I eventually was able to get it down to 700 rpm... I'm sure something logical was worng, but I never found it. Runs fine now... Weird...

 

[hochi97]

after i installed mine, it idled around 1000 rpm. i had to turn in the top screw almost all the way in to get it to 700 rpm.(i was actually afraid the set screw would fall out and get sucked into the intake). the bottom screw is about impossible to adjust. also, my instructions said to back the throttle body stop screw out of the picture completely.

 

[MUSTANGJOE]

Well i tried to install it again but the idle still keeps hanging! Maybe I didnt do it right...Is there anything that can give me this hanging idle?

 

[Michael Yount]

Some engines/ecu's are more susceptible to idle changes than others. There doesn't seem to be any rhyme or reason for it odd as that seems. The problem is that the ecu is programmed to try and control around 675 rpm, and attempts to change that are often "fought" by the computer. All the plate does is allow additional air to bypass the throttle plate without changing the throttle stop screw position. In a perfect world, if you sped it up that way, the computer would simply close off the iab solenoid a little more to try and return the speed to 675. As described above there are procedures that are geared to taking advantage of the ecu's ability to "learn" new operating parameters - like living with a higher idle speed. Just know that sometimes it works and sometimes it doesn't. I tried all of them I could find including the idle plate, and never achieved the idle stability/speed I wanted until I got a chip and changed the idle speed in the ecu. Good luck with it - it's one of the most common areas of struggle in modding these efi powerplants.

 

[stock88]

When I put my motor in from DSS (306), the literature they sent with it recommended a higher idle, around 1200! I went and got the IAC adjuster but have not put it on yet, so I guess I am hoping to have your "problem"!