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Doug
Doug, ASE Certified Technician
Category: Mitsubishi
Satisfied Customers: 8538
Experience:  Mitsubishi employed and Factory trained ASE certified technician
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Have evo8 car has po507 code mechanic replace iac now car

Customer Question

have evo8 car has po507 code mechanic replace iac now car idle high as hell remove air filter elbow and car idles at 1000 rpm need help nearest dealer 85 miles away
Submitted: 1 year ago.
Category: Mitsubishi
Expert:  Doug replied 1 year ago.

Hi,

Was the IAC actually conmfirmed failing or was it just replaced trying to fix the high idle? Was an aftermarket IAC used (there is a known issue with aftermarket IACs not working in this year range)?

Customer: replied 1 year ago.
mechanic suggest it got aftermarket
Expert:  Doug replied 1 year ago.

And I suspect that the condition did not improve at all with the IAC replacement, or even possibly got worse?

Customer: replied 1 year ago.
he unplugged it and stay at same idle put new iac in idle at 2800 rpm unplugged tps idle the same
returned tb elbow idle fall to 1100 rpm
Customer: replied 1 year ago.
Expert:  Doug replied 1 year ago.

Thanks.

First off we need to get the original IAC back in there. Aftermarket IACs are notorious for not working at all on these... blame cheap Chinese replicas I guess, but they are pretty much 1/10 success rate right out of the box.

With the original IAC installed, and the elbow installed (do not detach the duct work at all as it doesn't benefit or help in diagnosis), what is the idle speed exactly?
What about after you turn the AC on (or pull the steering wheel hard one direction), doe sthe idle go up or down at all?

Customer: replied 1 year ago.
idle goes down
Customer: replied 1 year ago.
900 to 850 idle normal an stay the same when ac on or in drive I told him to put the original back in then what next
Expert:  Doug replied 1 year ago.

Thanks, ***** ***** idle goes down, the IAC is not working.
I take it we haven't done that check on the original IAC yet and we're waiting now while it is reinstalled?

Customer: replied 1 year ago.
when he done how do I reach you
Expert:  Doug replied 1 year ago.

You can just reply back to this page.... this ill stay open while we wait.
If you need to close the page/turn off the computer/etc you can return to this page by logging into the site or clicking on one of the emails you should have received when I posted here.
Just allow me a few minutes to respond in case I am on a break or with another client the moment you post.

Customer: replied 1 year ago.
ok
Expert:  Doug replied 1 year ago.

Thanks

Customer: replied 1 year ago.
its idle at 2100 rpm code po507 stay solid with ac on or steering hard
Expert:  Doug replied 1 year ago.

Thanks.

Please leave the engine running at 2100 and take a can of brake cleaner or unlit propane and spray around the engine... the intake manifold, hoses, etc and see if you can manipulate the idle at all (if there is a vacuum leak it will draw in the added fuel and affect the idle).

Customer: replied 1 year ago.
ok going out now
Customer: replied 1 year ago.
no vacuum leaks
Expert:  Doug replied 1 year ago.

Thanks.
If there are no vacuum leaks then ruling anything terribly unusual out (like your timing belt set wrong, or bad custom tune) it sounds like you were probably right on the money originally with the IAC... you just need to get a good one.
If you do not have a dealer near you, then you should try the local junk yards (a used one is more reliable than a new aftermarket one), or checking online through a reputable dealer like Mentor Mitsubishi. You may also find a used one on evolutionm.net classifieds as well.

Whatever you do, just avoid aftermarket ones... as you've seen first hand, they are junk unfortunately.