Still idles high
Thread Starter
Instructor
Joined: Apr 2004
Posts: 217
Likes: 0
From: Winnipeg MB
Still idles high
I thought I had the problem solved, but I guess not.
85 Corvette. I couldnt get the idle down below 1100 rpm. I performed the IAC idle speed as per the instructions on this forum and then reset the tps to .54 volts. I fired the car up and it idled great at 620 rpm. When I rev the car up it wont come back below 1100-1300 rpm. No binds in the linkage or anything. I jump the diagnostic plug again with a paper clip and unplug the IAC and it idles great at 450 rpm. I re plug the IAC in and fire it up and the rpm steadies at 620. As soon as I rev it up, I cant get it below 1100 again. As its reving high I check the tps volts. They are over 2volts and the throttle is at idle. When I shut the car off, I can watch the tps volts lower until they are back at the .54v mark. What gives?
Note: there is no movement on the tps or throttle linkage when the voltage is dropping.
TPS problem? Oh ya, I replaced the IAC as well because I thought that was the problem.
Thanks
85 Corvette. I couldnt get the idle down below 1100 rpm. I performed the IAC idle speed as per the instructions on this forum and then reset the tps to .54 volts. I fired the car up and it idled great at 620 rpm. When I rev the car up it wont come back below 1100-1300 rpm. No binds in the linkage or anything. I jump the diagnostic plug again with a paper clip and unplug the IAC and it idles great at 450 rpm. I re plug the IAC in and fire it up and the rpm steadies at 620. As soon as I rev it up, I cant get it below 1100 again. As its reving high I check the tps volts. They are over 2volts and the throttle is at idle. When I shut the car off, I can watch the tps volts lower until they are back at the .54v mark. What gives?
Note: there is no movement on the tps or throttle linkage when the voltage is dropping.
TPS problem? Oh ya, I replaced the IAC as well because I thought that was the problem.
Thanks
Le Mans Master
Joined: Feb 1999
Posts: 9,922
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
I have been preaching this a lot lately. Wether it is right or not, the IAC can cause lots of issues.
Check your IAC. It will not throw codes, but will just die, or run bad as many have found. Scanning only shows what the ecm is telling it to do.
http://shbox.com/1/iac2.jpg
Check your IAC. It will not throw codes, but will just die, or run bad as many have found. Scanning only shows what the ecm is telling it to do.
http://shbox.com/1/iac2.jpg
Thread Starter
Instructor
Joined: Apr 2004
Posts: 217
Likes: 0
From: Winnipeg MB
Hi
This is a brand new IAC. I thought the IAC was the problem, but it is doing the same thing with the new IAC.
After the car is warmed up, the TPS volts measures over 2 volts at idle(1100-1300rpm) where it measured .54 when I originally set it.
Does that make sense?
This is a brand new IAC. I thought the IAC was the problem, but it is doing the same thing with the new IAC.
After the car is warmed up, the TPS volts measures over 2 volts at idle(1100-1300rpm) where it measured .54 when I originally set it.
Does that make sense?
Le Mans Master
Joined: Feb 1999
Posts: 9,922
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
If the TPS is measuring this much voltage it may be bad, unless your throttle body is sticking, its just a potentiometer. I would see if you can get another one off of another car or test it from idle to WOT and see what she does. She is obviously telling the ecm she is opened up quite a bit.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Originally Posted by Jinxie
Hi
This is a brand new IAC. I thought the IAC was the problem, but it is doing the same thing with the new IAC.
After the car is warmed up, the TPS volts measures over 2 volts at idle(1100-1300rpm) where it measured .54 when I originally set it.
Does that make sense?
This is a brand new IAC. I thought the IAC was the problem, but it is doing the same thing with the new IAC.
After the car is warmed up, the TPS volts measures over 2 volts at idle(1100-1300rpm) where it measured .54 when I originally set it.
Does that make sense?
RACE ON!!!
