1994 high idle
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
There is a process for resetting the IAC valve. A quick search produced these:
https://www.corvetteforum.com/forums...re-please.html
https://www.corvetteforum.com/forums...alve-then.html
https://www.corvetteforum.com/forums...procedure.html
https://www.corvetteforum.com/forums...e-setting.html
https://www.corvetteforum.com/forums...re-please.html
https://www.corvetteforum.com/forums...alve-then.html
https://www.corvetteforum.com/forums...procedure.html
https://www.corvetteforum.com/forums...e-setting.html
Thread Starter
Instructor
Joined: Nov 2004
Posts: 230
Likes: 1
thanks everyone for the input.
soaked the throttle body in carburetor clearer reassembled and mounted,new gaskets .
fired right up, sounded good,idle around 850 not great but much better.
got it down off the jacks and turned the key and it just cranked until I pumped the gas petal.
Strange.
Drove around the block pulled into the garage and steam coming out from under the hood.
steam and water shooting out of the top tank cap. digital gauge said 211.
Bad cap???
Heres my question......what kind of Corvette dosent want to be driven???????????
soaked the throttle body in carburetor clearer reassembled and mounted,new gaskets .
fired right up, sounded good,idle around 850 not great but much better.
got it down off the jacks and turned the key and it just cranked until I pumped the gas petal.
Strange.
Drove around the block pulled into the garage and steam coming out from under the hood.
steam and water shooting out of the top tank cap. digital gauge said 211.
Bad cap???
Heres my question......what kind of Corvette dosent want to be driven???????????
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
thanks everyone for the input.
soaked the throttle body in carburetor clearer reassembled and mounted,new gaskets .
fired right up, sounded good,idle around 850 not great but much better.
got it down off the jacks and turned the key and it just cranked until I pumped the gas petal.
Strange.
Drove around the block pulled into the garage and steam coming out from under the hood.
steam and water shooting out of the top tank cap. digital gauge said 211.
Bad cap???
Heres my question......what kind of Corvette dosent want to be driven???????????
soaked the throttle body in carburetor clearer reassembled and mounted,new gaskets .
fired right up, sounded good,idle around 850 not great but much better.
got it down off the jacks and turned the key and it just cranked until I pumped the gas petal.
Strange.
Drove around the block pulled into the garage and steam coming out from under the hood.
steam and water shooting out of the top tank cap. digital gauge said 211.
Bad cap???
Heres my question......what kind of Corvette dosent want to be driven???????????
Thread Starter
Instructor
Joined: Nov 2004
Posts: 230
Likes: 1
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
I usually scan the ECM and the sensor to see if it matches for ECT and air temperature. Gauge has been known to be off
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
So easy a caveman can do it. 
Say you use the scanner and see that the ECM reports an Intake Air Temp of 68 degrees, you take your infra red thermometer and hit the IAT sensor. It should be 68 degrees give or take a few. Coolant Temp Sensor? See above. Tach? Look at the tach and see what the scanner says for RPM. If they are different, you have an issue.
Say you use the scanner and see that the ECM reports an Intake Air Temp of 68 degrees, you take your infra red thermometer and hit the IAT sensor. It should be 68 degrees give or take a few. Coolant Temp Sensor? See above. Tach? Look at the tach and see what the scanner says for RPM. If they are different, you have an issue.
Thread Starter
Instructor
Joined: Nov 2004
Posts: 230
Likes: 1
So easy a caveman can do it.
Say you use the scanner and see that the ECM reports an Intake Air Temp of 68 degrees, you take your infra red thermometer and hit the IAT sensor. It should be 68 degrees give or take a few. Coolant Temp Sensor? See above. Tach? Look at the tach and see what the scanner says for RPM. If they are different, you have an issue.
Say you use the scanner and see that the ECM reports an Intake Air Temp of 68 degrees, you take your infra red thermometer and hit the IAT sensor. It should be 68 degrees give or take a few. Coolant Temp Sensor? See above. Tach? Look at the tach and see what the scanner says for RPM. If they are different, you have an issue.
Can you recommend a good one???
Then all I need is a caveman!!
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Thread Starter
Instructor
Joined: Nov 2004
Posts: 230
Likes: 1
I am back messing around with this thing again.
Do I have to have a scanner to do this?
I sprayed the mass air sensor with electronic cleaner , reassembled and my idle is back up to 1600.
Im thinking I need a new idle air control or it needs to be reset
any help appreciated
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
OK, caveman here. Can anyone explain to me how to reset the Idle Air Control in plain english without abbreviations ?
I am back messing around with this thing again.
Do I have to have a scanner to do this?
I sprayed the mass air sensor with electronic cleaner , reassembled and my idle is back up to 1600.
Im thinking I need a new idle air control or it needs to be reset
any help appreciated
I am back messing around with this thing again.
Do I have to have a scanner to do this?
I sprayed the mass air sensor with electronic cleaner , reassembled and my idle is back up to 1600.
Im thinking I need a new idle air control or it needs to be reset
any help appreciated
Scan for closed loop. Should be yes or no thing in "closed loop" column
If you are in closed loop, check the scanner for coolant temp. Hit the temp sensor with an infra red gun. The values should be about the same,
Not sure if there is an intake or ambient air temp sensor in your car. If there is, repeat the above to make sure they are reading right. If there isn't, get a temp reading of the air in the area and it should be about the same for the ECM reading.
Move on to Idle counts. See what reading you are getting. At this point, it should be about 20-30 counts. IF you have 0 counts, you probably have an air leak and we need to hunt it further.
Check the TPS voltage and see what it is.
Thread Starter
Instructor
Joined: Nov 2004
Posts: 230
Likes: 1
This is what I do after running the car for a bit so it gets to a stable operating temp. Everythign but the engine is shut off. No AC, no music, no lights, nothing. I don't want somethign to raise the idle.
Scan for closed loop. Should be yes or no thing in "closed loop" column
If you are in closed loop, check the scanner for coolant temp. Hit the temp sensor with an infra red gun. The values should be about the same,
Not sure if there is an intake or ambient air temp sensor in your car. If there is, repeat the above to make sure they are reading right. If there isn't, get a temp reading of the air in the area and it should be about the same for the ECM reading.
Move on to Idle counts. See what reading you are getting. At this point, it should be about 20-30 counts. IF you have 0 counts, you probably have an air leak and we need to hunt it further.
Check the TPS voltage and see what it is.
Scan for closed loop. Should be yes or no thing in "closed loop" column
If you are in closed loop, check the scanner for coolant temp. Hit the temp sensor with an infra red gun. The values should be about the same,
Not sure if there is an intake or ambient air temp sensor in your car. If there is, repeat the above to make sure they are reading right. If there isn't, get a temp reading of the air in the area and it should be about the same for the ECM reading.
Move on to Idle counts. See what reading you are getting. At this point, it should be about 20-30 counts. IF you have 0 counts, you probably have an air leak and we need to hunt it further.
Check the TPS voltage and see what it is.
I am not current on these types of tools yet.
I'm open to recommendations.
Thread Starter
Instructor
Joined: Nov 2004
Posts: 230
Likes: 1
I have been searching and I am not getting a clear idea which ones read what you are talking about
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
http://www.ebay.com/itm/Snap-On-MT25...946833&vxp=mtr
Something like that maybe? if the scanner is cheap enough but with no cartridges or the wrong cartridges, you can buy it and sell back the cartridges and buy the right one.
Thread Starter
Instructor
Joined: Nov 2004
Posts: 230
Likes: 1
Problem is the C4 is considered OBSOLETE. Auto X-ray got bought out by Actron and the newer Actron scanners don't work. Either get a GM Tech 1 or a Snap On. Those would be your simplest bets.
http://www.ebay.com/itm/Snap-On-MT25...946833&vxp=mtr
Something like that maybe? if the scanner is cheap enough but with no cartridges or the wrong cartridges, you can buy it and sell back the cartridges and buy the right one.
http://www.ebay.com/itm/Snap-On-MT25...946833&vxp=mtr
Something like that maybe? if the scanner is cheap enough but with no cartridges or the wrong cartridges, you can buy it and sell back the cartridges and buy the right one.
Melting Slicks
Joined: Oct 2007
Posts: 2,310
Likes: 9
From: KB7TIF Ville NV
Its What I have and is very elaborate, Not just a scanner, too bad your not close id let you borrow.
Not cheap http://www.ebay.com/itm/tech-1-scann...618826&vxp=mtr
Last edited by illenema; Dec 19, 2016 at 01:07 PM.
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
How about the vetronics Tech-1A scanner
Its What I have and is very elaborate, Not just a scanner, too bad your not close id let you borrow.
Not cheap http://www.ebay.com/itm/tech-1-scann...618826&vxp=mtr
Its What I have and is very elaborate, Not just a scanner, too bad your not close id let you borrow.
Not cheap http://www.ebay.com/itm/tech-1-scann...618826&vxp=mtr
Still, I'd get the Snap On MT2500 unit since I can get different modules and make it work for a bunch of other cars unless you are going to dedicate this scanner to that range of cars only. Not sure what else it can do
Thread Starter
Instructor
Joined: Nov 2004
Posts: 230
Likes: 1
Nice things cost money. http://www.ebay.com/itm/Vetronix-Tec...3D252683451624
Still, I'd get the Snap On MT2500 unit since I can get different modules and make it work for a bunch of other cars unless you are going to dedicate this scanner to that range of cars only. Not sure what else it can do
Still, I'd get the Snap On MT2500 unit since I can get different modules and make it work for a bunch of other cars unless you are going to dedicate this scanner to that range of cars only. Not sure what else it can do
Thank you everyone,
Last night found the culprit,a broken vacuum check valve ,passenger side intake manifold.
Yay, I can drive my car again!!!.......now for that heater core
Team Owner
Joined: Jul 2004
Posts: 28,474
Likes: 3,291
From: Hartford WI
You lucked out but I'd get the scanner for the next time. That way you practice with it so you are familiar. If I had that scanner, I'd see the IAC counts were 0 and be able to know that there is a leak somewhere otherwise I might be chasing a leak that doesn't exist. Just my $0.02