Idle Problems
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Joined: Nov 2010
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Idle Problems
I just bought an '85 and am absolutely thrilled.
I'm not much of a gearhead, and it's my first Vette, so forgive my layman's description of the weird idling.
The car's idle RPMs seem to jump around a bit when I'm sitting at a red light...the RPMs will jump up from 590 or so to about 650, and then the "service engine soon" light will pop on. After a few minutes, the light goes away, but the problem has occurred a few times and seems to come back when I'm idling. Anyone know what that's all about?
I'm not much of a gearhead, and it's my first Vette, so forgive my layman's description of the weird idling.
The car's idle RPMs seem to jump around a bit when I'm sitting at a red light...the RPMs will jump up from 590 or so to about 650, and then the "service engine soon" light will pop on. After a few minutes, the light goes away, but the problem has occurred a few times and seems to come back when I'm idling. Anyone know what that's all about?
Burning Brakes
Joined: Jun 2003
Posts: 1,079
Likes: 1
From: Niagara Falls ON
New to Corvettes? Get a service manual...it will help.
What code are you getting?
Idling issues. Check your IAC, TPS, and don't never overlook the obvious or the simple...check your air filter to make sure it isn't clogged.
You can get the IAC and TPS proceedure easily on this site. Lots of people will have good info to walk you through it.
Bill
What code are you getting?
Idling issues. Check your IAC, TPS, and don't never overlook the obvious or the simple...check your air filter to make sure it isn't clogged.
You can get the IAC and TPS proceedure easily on this site. Lots of people will have good info to walk you through it.
Bill
Le Mans Master
Joined: Aug 2007
Posts: 8,735
Likes: 412
From: WV
Check the above items, but it could be as simple as a vacuum leak. The tubing and gaskets on these cars is old and can break causing a leak that will make the cars idle fluctuate..This is a common problem on 20+ year old cars..WW
Pro
Joined: Mar 2006
Posts: 691
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From: Wayne NJ
Injectors maybe. I had idle issues when I first got my 88, it would jump around 600-800 all the time, then it went to starting issues. I replaced my injectors,IAC and my MAF burn off relay and she has run better then new ever sense. A couple hundred bucks for piece of mind.
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Hmm, whatever I find by checking the codes, it wouldn't be something I'd know how to remedy anyway. Like I said, I'm not much of a gearhead. 
The car I bought just went from a 1,000 mile per year extra car to being my daily driver, so it may need to adjust to being driven every day. I'm going to keep an eye on the spikes in idle RPMs, and if it stays the same or gets worse, it'll probably need a trip back to the shop to get it running better.
This doesn't seem to be a problem that needs urgent attention (unless it starts getting worse)...right?
The car I bought just went from a 1,000 mile per year extra car to being my daily driver, so it may need to adjust to being driven every day. I'm going to keep an eye on the spikes in idle RPMs, and if it stays the same or gets worse, it'll probably need a trip back to the shop to get it running better.
This doesn't seem to be a problem that needs urgent attention (unless it starts getting worse)...right?
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
If you are not planning to work on the car yourself, the most important thing you can do is to find a reliable independent shop or mechanic to do it for you. IMO, the dealer is not the best choice. Ask around if you don't know of a shop, you need a place that is familiar with 20+ year old electronics, ideally, with Corvette, or at least, GM electronics, and has a good reputation. It's unlikely that a dealer will have anyone who has ever been under the hood of a C4. If you are of a mind to dip your toe into DIY repairs, there is lots of help and info on this forum, many knowledgeable members.
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Yeah, my dad has a guy that works on his vintage cars, and the guy has plenty of experience with older cars. He's got a '68 Camaro in his shop now, and he's totally restoring a Chevelle too. This guy is legit and my dad trusts him, so I think that's my best bet.
By the way, I've discovered that my car seems to idle more smoothly in neutral, so I'm just slipping it into neutral at lights and that's keeping the "service engine soon" light off. Weird.
By the way, I've discovered that my car seems to idle more smoothly in neutral, so I'm just slipping it into neutral at lights and that's keeping the "service engine soon" light off. Weird.
