86L high Idle
Thread Starter
7th Gear
Joined: Aug 2006
Posts: 7
Likes: 0
86L high Idle
Hi, I'm new to post and it seems there are lots of knowledgable people here. My question has a few parts. A) I have an 86L, 94K miles just bought recently so I do not know the maintenance history. I was popping a code 33 so I took it to the corvette dealership here in town an they changed the MAF relays. That did nothing. The symtoms are in the mornig it idles high 1000rpm and when I slow from a short exceleration it trips the SES light and runs very rough. I stop at a light, she dies, restart and the light is gone and it runs fine for the rest of the day. B) Even without the SES light on the idle is very high, right now it sits at 1200rpm...do you think the idle is caused by problem A? Any help is truely appreciated.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Originally Posted by slvr86
I was popping a code 33
More often than not a high idle can be traced back to a vacuum leak. Also if the engine is getting air that the MAF isn't passing, the readings from the MAF may not "fit" with the other conditions the ECM is receiving. Be aware that codes get set because the ECM receives info that doesn't meet preset parameters. The code indicates the source of the, out of parameter data, but not the cause. If you plan to work on this car you will NEED a FSM (Factory Service Manual). Not only does it describe repair procedures, it tells how the various systems work, what readings cause a code to be sent from that system, and trouble shooting charts to help you diagnose the cause of the problem. Just as the shop didn't replace your MAF sensor, the code 33 doesn't necessarily mean that sensor is bad.
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Thread Starter
7th Gear
Joined: Aug 2006
Posts: 7
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Once again this morning it drove rough. It seems to be that way until it warms up...If it is a vaccuum problem wouldn't it run rough all the time? I'm guessing it may have something to do when it changes from open loop to close loop. Isn't there a Idle Air Pin or something that should change once its warm? Any validity to that train of thought?
Le Mans Master
Joined: Feb 2006
Posts: 8,753
Likes: 9
From: Louisiana
If the code is still present now...I suggest you order a FSM as stated above, unless you are willing to pay a mechanic to change parts as what you have described. The code means that the ECM has sensed a out-of-range limit that is preset in it. Meaning that it could be a faulty/dirty MAF, ciruit, or connections either at the MAF, relays, or ECM. With out the FSM to guide you through the steps to troubleshoot the problem, it will take longer and you will spend more money doing it. Agent86 (forum member) has most all the codes on pdf, and it would save you from getting the FSM at this time. Maybe he/other will chime in. 
I have a 86E and this is a great place to find info and help. I would fix the code before doing anything else.
I have a 86E and this is a great place to find info and help. I would fix the code before doing anything else.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by slvr86
It seems to be that way until it warms up...If it is a vaccuum problem wouldn't it run rough all the time? I'm guessing it may have something to do when it changes from open loop to close loop.
Originally Posted by slvr86
slvr86
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