87 coolant fan
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
Hey, don't beat yourself up. nobody on this forum knows everything. I have had this car of mine for almost 17 years. I am still finding out new things about it.
Remember, they had hundreds of engineers design these cars every year, and it's up to each one of us to discover all the secrets they hold.
There are books, FSMs, videos, the cars, and we have each other. It's great to bounce things off of someone who has dealt with different problems.
For instance, I have no idea where they put the inside temp sensor on a roadster since I've never owned one, or for that matter, ridden in one.
Remember, nobody knows it all.
Remember, they had hundreds of engineers design these cars every year, and it's up to each one of us to discover all the secrets they hold.
There are books, FSMs, videos, the cars, and we have each other. It's great to bounce things off of someone who has dealt with different problems.
For instance, I have no idea where they put the inside temp sensor on a roadster since I've never owned one, or for that matter, ridden in one.
Remember, nobody knows it all.
Cruising
Joined: Jul 2011
Posts: 13
Likes: 0
From: Pecks Mill West Virginia
Hey, don't beat yourself up. nobody on this forum knows everything. I have had this car of mine for almost 17 years. I am still finding out new things about it.
Remember, they had hundreds of engineers design these cars every year, and it's up to each one of us to discover all the secrets they hold.
There are books, FSMs, videos, the cars, and we have each other. It's great to bounce things off of someone who has dealt with different problems.
For instance, I have no idea where they put the inside temp sensor on a roadster since I've never owned one, or for that matter, ridden in one.
Remember, nobody knows it all.
Remember, they had hundreds of engineers design these cars every year, and it's up to each one of us to discover all the secrets they hold.
There are books, FSMs, videos, the cars, and we have each other. It's great to bounce things off of someone who has dealt with different problems.
For instance, I have no idea where they put the inside temp sensor on a roadster since I've never owned one, or for that matter, ridden in one.
Remember, nobody knows it all.
Cruising
Joined: Jul 2011
Posts: 13
Likes: 0
From: Pecks Mill West Virginia
One more question if anyone can help, it would be appreciated. I have a code 34, on the Car, the 87.....it appears that the problem is a ground to short, as the sensors have been replaced and the repair manual suggests there might be a faulty ground as the ECM was recently replaced as well (the entire thing happened because of a failed ECM and it ran great, for a few days after replacement),THEN A CODE 22 CAME UP, CLEARED THAT PROBLEM with Cleaning the Throttle Body of Carbon, and replacing the TBS....The car runs good except at low idle...and the Check Engine light continues to stay on until cleared...then the normal code 12 followed by the 34. Any suggestions?
Question I have determined the Green wire to be the ground....could the problem be checked by grounding it directly? Could this possibly damage the new MAF sensor? As I said previously, any help would be greatly appreciated before I cause more damage through ignorance. The car runs great, except at low Idle...it stalls only occasionally, it has great throttle response mid range to high end and purrs like a kitten, but the lights stays on until cleared, then once operating temp is reached...the code 34 pops up again and stays on. Is there any way to check for a Short to Ground...void of having to pay a Tech. for something that could be as simple as a bad ground? It was checked for voltage... I am no electrician but it appeared the voltage was correct.
Question I have determined the Green wire to be the ground....could the problem be checked by grounding it directly? Could this possibly damage the new MAF sensor? As I said previously, any help would be greatly appreciated before I cause more damage through ignorance. The car runs great, except at low Idle...it stalls only occasionally, it has great throttle response mid range to high end and purrs like a kitten, but the lights stays on until cleared, then once operating temp is reached...the code 34 pops up again and stays on. Is there any way to check for a Short to Ground...void of having to pay a Tech. for something that could be as simple as a bad ground? It was checked for voltage... I am no electrician but it appeared the voltage was correct.
Last edited by User; Aug 6, 2011 at 10:31 PM.
Team Owner
Joined: Jan 2003
Posts: 20,306
Likes: 242
From: Summerland B.C. Canada
One more question if anyone can help, it would be appreciated. I have a code 34, on the Car, the 87.....it appears that the problem is a ground to short, as the sensors have been replaced and the repair manual suggests there might be a faulty ground as the ECM was recently replaced as well (the entire thing happened because of a failed ECM and it ran great, for a few days after replacement),THEN A CODE 22 CAME UP, CLEARED THAT PROBLEM with Cleaning the Throttle Body of Carbon, and replacing the TBS....The car runs good except at low idle...and the Check Engine light continues to stay on until cleared...then the normal code 12 followed by the 34. Any suggestions?
Question I have determined the Green wire to be the ground....could the problem be checked by grounding it directly? Could this possibly damage the new MAF sensor? As I said previously, any help would be greatly appreciated before I cause more damage through ignorance. The car runs great, except at low Idle...it stalls only occasionally, it has great throttle response mid range to high end and purrs like a kitten, but the lights stays on until cleared, then once operating temp is reached...the code 34 pops up again and stays on. Is there any way to check for a Short to Ground...void of having to pay a Tech. for something that could be as simple as a bad ground? It was checked for voltage... I am no electrician but it appeared the voltage was correct.
Question I have determined the Green wire to be the ground....could the problem be checked by grounding it directly? Could this possibly damage the new MAF sensor? As I said previously, any help would be greatly appreciated before I cause more damage through ignorance. The car runs great, except at low Idle...it stalls only occasionally, it has great throttle response mid range to high end and purrs like a kitten, but the lights stays on until cleared, then once operating temp is reached...the code 34 pops up again and stays on. Is there any way to check for a Short to Ground...void of having to pay a Tech. for something that could be as simple as a bad ground? It was checked for voltage... I am no electrician but it appeared the voltage was correct.
What is your TPS idle voltage ?
34 from my 86 FSM http://members.shaw.ca/corvette86/Code%2034.pdf
Cruising
Joined: Jul 2011
Posts: 13
Likes: 0
From: Pecks Mill West Virginia
Code 34 can be caused by a rough unstable idle. You have a bad idle and after that it's all good, so your 34, has a good chance of being the result of a bad idle.
What is your TPS idle voltage ?
34 from my 86 FSM http://members.shaw.ca/corvette86/Code%2034.pdf
What is your TPS idle voltage ?
34 from my 86 FSM http://members.shaw.ca/corvette86/Code%2034.pdf
This is driving me insane. I suppose that I am going to have to engage a professional tech to check out the wiring system as I have exhausted both my knowledge and patience. I have replaced senors, MAF, TPS, as well as both relays behind the side battery panel as well as checking the junction boxes for corrosion, bought a new battery, cleaned the carbon from the Throttle Body and replaced all the gaskets making sure of a tight seal....and replaced the ECM as well as tuning the car up with New wires, spark plugs, Cap and Rotor and Positive Crank Vent value.
The car is driveable but at times it will stall and you have to limp home with a code 22 or 34 showing...and go through the routine again seeing if you have missed anything. Thanks for the help....but I believe its time to take her to the local Electric Shop that specializes in automotive electronics and allow them to find the SHORT to ground somewhere that I believe might be the culprit that is connected but loose somewhere in the system, just enough to drive ya crazy hunting it down, showing a good circuit 95% of the time. I also suspect that the problem has something to do with the fan, cooling input information going to the ECM...as the rough idle does not occur until the fan is engaged, which reminds me I replaced the sending unit under the throttle body as well...with no resulting help noted.
And you are correct....the ROUGH IDLE is causing the CODES...the problem is figuring out the source of the rough idle, as with anything electrical....one bad bite of errant information has a cascade effect and will cause false codes to result, but its constant in the air flow/fuel ratio somewhere AND has something to do with the operating temperature range.
Last edited by User; Aug 8, 2011 at 05:19 AM.
Team Owner
Joined: Jan 2003
Posts: 20,306
Likes: 242
From: Summerland B.C. Canada
Re fan
The fan will run when checking codes=Normal
The fan will run when some codes are set due to ECM going into "limp home" mode.
Your 22 is a TPS error, which is probably causing the rough idle, which then triggers the 34.
Get a meter and set you TPS idle voltage and check to see if the voltage increases smoothly as you open the throttle, reaching about 4.5v at WOT.
http://members.shaw.ca/corvette86/Code%2022.pdf
The fan will run when checking codes=Normal
The fan will run when some codes are set due to ECM going into "limp home" mode.
Your 22 is a TPS error, which is probably causing the rough idle, which then triggers the 34.
Get a meter and set you TPS idle voltage and check to see if the voltage increases smoothly as you open the throttle, reaching about 4.5v at WOT.
http://members.shaw.ca/corvette86/Code%2022.pdf
