88 I.A.C question
Thread Starter
Safety Car
Joined: Jul 2004
Posts: 3,835
Likes: 30
88 I.A.C question
..88 vette coup...quick question involving the iac...
..for 2 years now i have been chasing around a long cranking - hard starting problem and effectively gave up since the car does start(temp not an issue).....
..regarding the PINTLE of the I.A.C. - is the surface of the pintle supposed to be SMOOTH or ROUGH as in the appearance of it being pitted?
...to make it simple, that is the ONLY question i need answered and i do not need troubleshooting posts at this time.......thanks!
..for 2 years now i have been chasing around a long cranking - hard starting problem and effectively gave up since the car does start(temp not an issue).....
..regarding the PINTLE of the I.A.C. - is the surface of the pintle supposed to be SMOOTH or ROUGH as in the appearance of it being pitted?
...to make it simple, that is the ONLY question i need answered and i do not need troubleshooting posts at this time.......thanks!
Last edited by Da Mail Man; Jul 14, 2007 at 10:18 AM. Reason: spelling
Thread Starter
Safety Car
Joined: Jul 2004
Posts: 3,835
Likes: 30
.....that's what i was affraid of!......when i cleaned and reset mine some time ago, it was pretty damned rough!..ugh...maybe that could contribute to my long cranking hard starting problem although, the car starts a bit faster with the pedal to the floor (i know that it places the ecm into clear flood mode).....
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
it probably wouldn't hurt but from what you said that may not be the only troubleshooting needed.
Thread Starter
Safety Car
Joined: Jul 2004
Posts: 3,835
Likes: 30
Le Mans Master
Joined: May 2004
Posts: 5,866
Likes: 60
From: Hellinois
Finalist 2020 C4 of the Year - Modified
Maybe your hard start and hard brakes are both caused by the same problem,, vacuum leak. Also, yes the IAC's are the same. That particular IAC was used in quite a few GM cars.
Last edited by Midnight 85; Jul 14, 2007 at 10:31 AM. Reason: Added info
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
......i troubleshot this thing all the way to hell and back and can't find the problem...i have no idle or surging problems and today, i read an old thread where someone changed out their iac and it cleared up their problem.....(let me tell you about my damn brake problem!..only kidding although, it is a problem)....i have fred flintstone brakes!..
steve's 40th just posted a thread about a week ago on the same subject (IAC ). I don't think it could hurt that's for sure.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
2027 Corvette vs The World: Every C8 vs Its Closest Competitor
Joe Kucinski
10 Most Common Corvette Problems of the Last 20 Years!
Joe Kucinski
5 MOST and 5 LEAST Popular Corvette Model Years in History!
Joe Kucinski
2027 Corvette Buyer's Guide: Everything You Need to Know!
Joe Kucinski
Thread Starter
Safety Car
Joined: Jul 2004
Posts: 3,835
Likes: 30
iac goes, if i can determine that the 88 and 89's are the same, may swap it out...
....as far as the brakes go, i have a rather hard pedal but, have NO leaks in the booster or vacuum lines or a misadjusted actuator rod contacting the m/c.....hard pedal usually indicated booster/vac problem, mushy/low pedal usually means bad m/c......
Last edited by Da Mail Man; Oct 22, 2008 at 07:33 AM. Reason: spelling
Thread Starter
Safety Car
Joined: Jul 2004
Posts: 3,835
Likes: 30
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
I agree with post #2 about the pintle being smooth, but I don't see the IAC coming into play in a starting issue. If the pintle is scored or pitted, I can only see that as causing a slight leak, when it is supposed to be closed, like under high vacuum situations, as coming down a hill. Even if it were totally inoperable I don't see much effect on starting. However, if it were locked up closed, it could explain why opening the throttle helps starting. I'm betting you are barking up the wrong tree. I certainly wouldn't go buy one as a test, however of you have one available to sub for a test, go for it. My parts book shows the same part number IAC used from 1985 through 1988. The 1989 takes a different part number. They MAY be interchangeable, but the numbers are different.
RACE ON!!!
RACE ON!!!
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
The IAC is self-resetting. The pintle is retracted to prevent damage when (re)installing. The "reset procedure" isn't really necessary. The IAC will reset the first time it is warmed up and driven at approx 35 to 40 mph.
RACE ON!!!
RACE ON!!!
Race Director
Joined: Jun 2004
Posts: 13,939
Likes: 705
From: WI
My idea with the reset was to jumper the ALDL and let the pintle extend fully, then test it this way with a smooth IAC and with the rough IAC. This isn't really needed though since I agree the pitted one won't cause problems but he might want to test it. The rough IAC could be filed down and then tested to. I transgressed and posted troubleshooting ideas though. 
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by Aardwolf
My idea with the reset was to jumper the ALDL and let the pintle extend fully, then test it this way with a smooth IAC and with the rough IAC.
However, I question the validity of that test, because I believe, correct me if I am wrong, the IAC isn't closed at start up.
Originally Posted by Aardwolf
I transgressed and posted troubleshooting ideas though.
RACE ON!!!
Race Director
Joined: Jun 2004
Posts: 13,939
Likes: 705
From: WI
"and i do not need troubleshooting posts at this time" The OP likes his threads clean, it's tough to not put more thought into replies though.
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
hard starting
i think his hard start issue is the fuel runs back to the tank, and the pump has to bring it all the way back up to the fuel rail and pressurize it before it will run. It's not that it won't start, it's that it has no fuel
Thread Starter
Safety Car
Joined: Jul 2004
Posts: 3,835
Likes: 30
I agree with post #2 about the pintle being smooth, but I don't see the IAC coming into play in a starting issue. If the pintle is scored or pitted, I can only see that as causing a slight leak, when it is supposed to be closed, like under high vacuum situations, as coming down a hill. Even if it were totally inoperable I don't see much effect on starting. However, if it were locked up closed, it could explain why opening the throttle helps starting. I'm betting you are barking up the wrong tree. I certainly wouldn't go buy one as a test, however of you have one available to sub for a test, go for it. My parts book shows the same part number IAC used from 1985 through 1988. The 1989 takes a different part number. They MAY be interchangeable, but the numbers are different.
RACE ON!!!
RACE ON!!!