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IAC counts going to Zero! Hanging idle!

 
Old 05-15-2019, 10:08 PM
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Default IAC counts going to Zero! Hanging idle!

This is on my personal turbo truck. It currently has a ebay 92mm tb and a holley high ram intake. I am having an issue where it struggles on cold start up (have to pedal it for a lil bit) , Idle hangs around 1000rpm (750 commanded) and IAC counts go to zero at hot idle.

I have played with everything in the tune tht I can think of. I also had this issue with a stock tbss intake and ptm 92mm tb. I swapped to the holley high ram setup thinking it would help fix a cracked intake etc. Didn't work. I have been fighting this for a few weeks.

I can close tb blade all the way and counts still stay at 0. Ive checked all vaccum sources, intake leaks, etc. I cant find anything.

I have been tuning a lil over 4yrs and this is the first time ive had an issue like this tht I couldn't figure out. if anyone has any ideas im all ears. thanks.
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Old 05-15-2019, 11:43 PM
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how are you checking for leaks? Have you smoked it?
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Old 05-16-2019, 09:54 AM
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Is the engine able to actually reach the “desired idle rpm”? I’ve found that if this is unattainable, the “idle desired” aka IAC counts will keep going down to try and reach it.

Air essentially controls the rpm range (+/- off of target) at idle, spark maintains the target. If the rpm setting is too low for that cam, it’s not going to reach the “range” using air because vacuum (airflow) is reduced at low rpm. Try bumping the rpm up by 15-25 at a time until the counts stabilize.

You can can play with spark a bit too, but with different setups the targets are all dependent on mods.

I think we’d all like our big *** nasty merican cams to idle at 550 but unfortunately physics has other plans...
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Old 05-16-2019, 11:32 AM
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You may need to epoxy aroun your TB to close the gap between blade and body.

Remove TB, shine a light behind it, see how much light gets through. If a lot, build up with epoxy or ditch the eBay TB for a NW
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Old 05-16-2019, 11:38 AM
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Yup....that's what i had to do. Worked fine afterwards.
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Old 05-16-2019, 12:39 PM
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Your sig cracks me up. its Running.... nevermind….
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Old 05-16-2019, 12:54 PM
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Sad but true
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Old 05-16-2019, 06:32 PM
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It actually hangs around 950rpm. Every now and thin when the iac counts are good it will idle at 750 with a nice lope. Sounds amazing around the idle. I can usually achieve this when coming to a stop at a light etc.

Thin counts go to zero and it seems like timing locks out and idle just hangs back up.

Ill try pulling the tb off and give it a look over. I feel like it is suspect at this point. Ill also try an idle around 950ish if tb checks out. Ill report back my findings. Thanks guys!
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Old Today, 04:10 PM
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i have similar issues with my car it wont return to adaptive idle all the time
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