High searching Idle

[XfireZ51]

Originally Posted by Vette73

Couldn't help but read this entire thread on engine idle......One question I have is, how accurate is the tachometers on these cars? I have a 91.....

Mine idles at between 900-1,000 rpm...Motor is fully ported with full exhaust and intake cams...

Even when my car was stock it seemed to favor anywhere from 850-950 usually..

I do notice at times when I pop it into neutral coming to a stop, it may take 5-10 seconds for the idle to " settle in" at around 900-1,000....

Forgive the ignorance , new bee here still learning...👍

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Not at all. Your questions are welcomed. That's the purpose of threads like this.
To your observation, the IAC controls have "delays" which will hold rpms up a bit using the IAC until you are at a stop. Those delays can be reduced. But IMO, the LT5 has a tendency to want to stall. It reacts quickly to inputs which makes it responsive, and when the motor is modified and events happen quicker, the stock settings represent somewhat of an "overreaction".
So it needs to be "toned down" a bit.

[Vette73]

Hey X fire thanks for getting back...I know this is common in the ZR-1,coming to a stop with the car in neutral , the idle finds a way to "settle" in ....

My other Corvette I have is a 73, no computer of course and a grand total of about 5 fuses,don't even have seat belts and its a convertible, go figure....

Anyway as far as the idle settling in at times, is that common among late model corvettes?

I think I mentioned in a PM to you, I drove a 15 C7 at Ron fellows school.....Granted, your hammers to hell around that track but didn't really notice any idle searching so to speak..

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[XfireZ51]

Vette,

I had a highly modified 84 Xfire Z51 before owning a ZR-1. I never had a hunting idle. When I depressed the clutch, motor would drop to 800rpm and stay there even as it was rolling. Not so much w the LT5. But I have been able to mitigate that w tuning but not completely. Witha modded motor, something like that can setup an oscillation that can get out of hand.

[Ccmano]

Originally Posted by Vette73

Couldn't help but read this entire thread on engine idle......One question I have is, how accurate is the tachometers on these cars? I have a 91.....

Mine idles at between 900-1,000 rpm...Motor is fully ported with full exhaust and intake cams...

Even when my car was stock it seemed to favor anywhere from 850-950 usually..

I do notice at times when I pop it into neutral coming to a stop, it may take 5-10 seconds for the idle to " settle in" at around 900-1,000....

Forgive the ignorance , new bee here still learning...👍

Sent from my LG-TP260 using ZR-1 Net Registry mobile app

Most likely your tach is off. They tend to show on the high side with age and they are all old. I would only trust a Tech1 or scanner of some type. I must say using ALDLDriod has been a positive experience.

Looks like your car was modified. I would check the chip and see how it was set up, if at all. 5-10 seconds for the idle to settle down when at full operating temp is not normal. It should linger at higher rpms as you come to a stop but should be back to normal within a second or two.
H

[Vette73]

Originally Posted by Ccmano

Most likely your tach is off. They tend to show on the high side with age and they are all old. I would only trust a Tech1 or scanner of some type. I must say using ALDLDriod has been a positive experience.

Looks like your car was modified. I would check the chip and see how it was set up, if at all. 5-10 seconds for the idle to settle down when at full operating temp is not normal. It should linger at higher rpms as you come to a stop but should be back to normal within a second or two.
H

I would think that as well,tach being a little off with age.....As far as 5-10 seconds to return to idle, its only really done that a hand full of times.....Basically,it is a few seconds to come down to idle....

Salute........

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[jss06c6]

Originally Posted by Vette73

I would think that as well,tach being a little off with age.....As far as 5-10 seconds to return to idle, its only really done that a hand full of times.....Basically,it is a few seconds to come down to idle....

Salute........

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That's completely normal. The tach in my '91 reads about 50 rpm high. I trust my scanner... Not enough difference to worry about for me.

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