82 CF ZZ4 idle speed

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Apr 25, 2012 | 07:23 AM

Aldo_45030

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Racer

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From: Harrison Ohio

82 CF ZZ4 idle speed

I have a 99 ZZ4 with crossfire injection and have been chasing a rough idle problem. COuld it be so simple as the wrong idle speed? I read somewhere the recommended ZZ4 speed is 650 rpm in gear i assume and the 82 crossfire is to be at 475 in gear. SUre does seem to idle better at 650 but does the ecm expect to see 475?

Apr 25, 2012 | 02:43 PM

MelWff

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Shouldnt the ECM be controlling the idle not the ECM expecting you to set an idle? Is this set up that you can read codes that the ECM may be throwing?

Apr 25, 2012 | 02:57 PM

Aldo_45030

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Racer

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From: Harrison Ohio

Quote:

Originally Posted by MelWff

Shouldnt the ECM be controlling the idle not the ECM expecting you to set an idle? Is this set up that you can read codes that the ECM may be throwing?

THat is my question is the ecm smart enough to adjust the physical setting of the idle to meet its predetermined idle speed or is the physical setting used as the base line idle when the ECM is reset by disconnection the neg at the battery?
I do not have anyway to monitor the ecm other tham the check engine light which currently has no codes.

One other question if i reset the physical idle do i need to reset the TPS to .525? i assume so since it is part of the steps when you balance the TBI's.

Apr 25, 2012 | 03:00 PM

Wrecked82

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From: Texas

Part of the balancing process for the crossfire is to set the idle using the large **** thing on the linkage on the passenger side tbi. Mine idles best at 650 also, maybe a tad more. If I had it down at 475, it would be like it is stumbling and wanting to die out. Somewhere in other articles, maybe a Chevy High Performance magazine article, they point out the cf likes the higher idle.

Apr 25, 2012 | 08:18 PM

terry82

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From: columbia city in

the computer will try to set the idle at 650 in gear .but it does not like vac leaks .if your tps is set it should not change .

Apr 25, 2012 | 08:53 PM

EmNash

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From: LI NY

When my idle stays high its time to hunt down a vacum leak. Follow the whistle or get a vacum tester. In park its between 600 and 800

Apr 26, 2012 | 10:13 AM

Wrecked82

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From: Texas

Apr 26, 2012 | 10:45 AM

Aldo_45030

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Racer

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From: Harrison Ohio

Pretty much eliminate possibility of a vacuum leak replaced every hose and sniffed around with propane and carb cleaner no change. I may have stumbled on to a possible wiring harness issue. I noticed when i close the hood the idle changes and sometime CEL blinks. I went to pull a code last night and the IAC's started to chatter,CEL dimmed so i went to the connections from the engine to the firewall and i could wiggle the harness and the stuff would chatter and light would flick and fade. Unfortunately before i could isolate it quit.
So answer this what connector / wire would cause the system to act like it was going into diagnostic mode? One more thing to not the computer codes all cleared out of the ECM also.