84 idle problem
Thread Starter
Instructor
Joined: Dec 2003
Posts: 136
Likes: 0
From: milton freewater oregon
84 idle problem
I have an 84, I've been having problems with the idle. When I was using 92 octane fuel I would always foul my plugs after a few thousand miles and my idle was always kind of high, about 1000!. So I switched to 87 octane and the car was idling better in drive, about 700 to 800. but now with the car in park the car started idling between 1000 and 1300 while it is inpark and upto opertaing tempature.
Could it be the IAC or is it the ECM. Not much of a mechanic, so I could you some help.
Could it be the IAC or is it the ECM. Not much of a mechanic, so I could you some help.
Race Director
Joined: Aug 2002
Posts: 13,356
Likes: 0
From: tucson AZ
St. Jude Donor '04 & '05
Re: 84 idle problem (not4kt)
I have an '84, and never had the problems you talk about.
Try the Crossfire Forum http://www.crossfire.webhop.net
Great info on our crossfire vettes.
Good Luck
tony
:thumbs:
Try the Crossfire Forum http://www.crossfire.webhop.net
Great info on our crossfire vettes.
Good Luck
tony
:thumbs:
Pro
Joined: Apr 2003
Posts: 552
Likes: 13
From: Oz
Re: 84 idle problem (not4kt)
I'll bet you have a vacuum leak. Check all your hoses, around the base of the throttle bodies and also around the perimeter of the crossfire manifold top lid.
Some guys use a piece of hose to the ear, or spray carb cleaner around suspect areas.. The idle will change if the carb cleaner is sucked in thru a leak.
Ben.
Some guys use a piece of hose to the ear, or spray carb cleaner around suspect areas.. The idle will change if the carb cleaner is sucked in thru a leak.
Ben.
Heel & Toe
Joined: Aug 2002
Posts: 22
Likes: 0
From: Murphy NC
Re: 84 idle problem (not4kt)
Check your coolant temperature sensor. If it's bad the ECM will never get into closed loop, your idle will remain high because the ECM thinks the engine is cold, it will also result in a richer mixture that will foul the plugs. A vacuum leak can result in a high idle, but it usually causes a lean condition. If the plugs are black (fuel not oil) I would lean towards the CTS. By the way it's the one on the front of the intake, not the one in the passenger side head.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: 84 idle problem (not4kt)
As mentioned, the CTS or vacuum leaks are prime suspects. It is VERY unlikely it is an ECM problem. There is some misinformation, here, however. The octane of the gasoline will have NO influince over the idle speed. Something else must have changed when you switched fuels, that you may not have noticed. The ONLY thing octane does is inhibit knock. It doesn't affect idle speed , nor does it foul plugs. Fouled plugs indicate a overly rich mixture, which could result from either aforementioned cause. Good luck, and...
RACE ON!!!
RACE ON!!!
Race Director
Joined: Dec 2003
Posts: 14,148
Likes: 936
From: Fremont Ca
2022 C4 of the Year Finalist - Modified
Re: 84 idle problem (CFI-EFI)
I prefer a spray bottle with water when looking for a vac leak.If you get carb cleaner on a painted surface,it could screw it up.
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