Replaced IAC now idling very high

[svabo]

Hi All, new to the forum and new to.the Pajero world.
Recently bought a Pajero NM 3.5 petrol auto that was idling very low and stalling. After some research it sounded like the IAC valve.
Couldn't find an OEM at a wreckers here in Sydney so got a cheap one of eBay for $20 just to test if it is the IAC. Since.replacing it the idle has jumped to 2k rpm while in park of neutral. Is about 1300rmp whilst in drive.
Any ideas?
Thanks again

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[nj swb]

Initial thought is one of two things.

1. Your eBay IAC is a dud.

2. A previous owner has adjusted an air bypass to compensate for the previous dud IAC, and is now allowing too much air to bypass.

Please note that I don't even know if your 3.5 has an air bypass adjustment, but hopefully somebody else will know one way or the other.

[svabo]

That was my initial thought that it was a dud.
Just thought someone may have experienced this before. Heard about the idle relearn but didn't think it would effect the idle speed that much.

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[geopaj]

After installing the IAC, did you disconnect the battery (for a minute or two) to allow the computer to reset?

From memory, when I installed a replacement IAC into my old V6 NL (which has a similar engine & ECU) to yours, I had to reset the computer by disconnecting the battery before it would idle probably.

The other option is your eBay IAC is faulty.

[svabo]

Thanks for your reply. I did disconnect the battery after I did the swap. Did yours idle high/low intially then settle? If so how long did it take to settle down?

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[disco stu]

Idle air bypass was on model before, so i'm assuming it will be on that one. Takes a phillips head and is on top of the throttle body on the rear side. I would try screwing that in to try and bring it down, just count the turns so you can return it to the same place if needed

[svabo]

Thanks, will give it a try. Shouldn't really have to manually adjust it in theory though if the IAC is doing its job right?

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[nj swb]

Thanks, will give it a try. Shouldn't really have to manually adjust it in theory though if the IAC is doing its job right?

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If it's there, Mitsubishi installed it for a reason - presumably to ensure a minimum air flow regardless of IAC operation.

If the old IAC wasn't doing its job properly, or the throttle body was simply gummed up, then the previous owner may have adjusted the bypass to compensate. You may need to now uncompensate.

[svabo]

Yes true, thanks for your help mate

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[craka]

Is it possible the throttle body just needs a clean?
From memory the main issue on the early gen2 at least were that the idle control motor failure itself wasn't the issue but the carbon build up on the plunger it pushed in and out.

[svabo]

Before replacing the IAC I gave the throttle body and the inlet where IAC site a good clean with throttle body cleaner. Cleaned all the edges of the butterfly. Wasn't sticking and creating a good deal from what I saw

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[Alex86]

NJ said the air bypass may have been adjusted.
That a different name for the “idle screw” adjustment?
Either way, could be a likely culprit. Sorry I don’t know how to set this thing correctly.

[disco stu]

No, different to the idle screw that opens butterfly further. Technically shouldn't touch the idle screw on efi. This one is down in a hole in the throttle body that is in line with the butterfly and is just a needle that allows a certain amount of air past it at all times. Takes a Philips head screw driver

[disco stu]

This picture should help give an idea where it is

https://images.app.goo.gl/g1sBFvQn2Y2jxzbZ9

[svabo]

Thanks for the help legends.. I'll give it a shot tomorrow.

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