Adjustable TPS '87 automatic
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Melting Slicks
Joined: Jul 2004
Posts: 2,018
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From: OR
Adjustable TPS '87 automatic
My car idles at spec, but is a touch slower than I'd like it to be. It is not adjustable. I see Corvette Central sells a TPS that is adjustable. The original is not. Could I use that to crank the idle up 50 rpms or so? I'm sure the more right way would be if the computer was reprogramed some how so it was done with the IAC, but I don't know how to do that.
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Cruise-In II Veteran
Originally Posted by newbecorvetteguy
My car idles at spec, but is a touch slower than I'd like it to be. It is not adjustable. I see Corvette Central sells a TPS that is adjustable. The original is not. Could I use that to crank the idle up 50 rpms or so? I'm sure the more right way would be if the computer was reprogramed some how so it was done with the IAC, but I don't know how to do that.
Non adjustable TPS came on later TPI cars.
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Joined: Sep 2000
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From: The Top of Utah
Originally Posted by newbecorvetteguy
My car idles at spec, but is a touch slower than I'd like it to be. It is not adjustable.
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Safety Car
Joined: May 2006
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From: Salem NH
Originally Posted by CFI-EFI
You are right. The idle is not (by normal means) adjustable. The TPS on all C4s up to 1990 were adjustable. First get a correct, adjustable, TPS and adjust it correctly. The TPS does not determine the idle speed. The prom has the idle speed burned into it. If you would like a different idle speed, the proper way is to (or have) a new chip burned with your desires. Within reasonable limits, the TPS adjustment doesn't affect the idle speed.
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-- Joe
Burning Brakes
Joined: Oct 2005
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From: OAKLEY CA
Originally Posted by CFI-EFI
You are right. The idle is not (by normal means) adjustable. The TPS on all C4s up to 1990 were adjustable. First get a correct, adjustable, TPS and adjust it correctly. The TPS does not determine the idle speed. The prom has the idle speed burned into it. If you would like a different idle speed, the proper way is to (or have) a new chip burned with your desires. Within reasonable limits, the TPS adjustment doesn't affect the idle speed.
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Seafoam the idle settles at 600 to 700. Perhaps a good cleaning and base idle procedure would fix his idle to his liking.
Safety Car
Joined: May 2006
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From: Salem NH
Originally Posted by ED HEISER
You are of course correct in theory, but in practice on my 88, a higher tps setting such as .62 will raise the idle speed and increase throttle response. A shop near me likes to set them at .75 to .80 for this reason. This does not work well with an A4 such as mine as it bangs into gear at 1200 to 1300 rpms. I tried lots of settings, and settled on .54 in the end, after a TB (off car) and top end cleaning with
Seafoam the idle settles at 600 to 700. Perhaps a good cleaning and base idle procedure would fix his idle to his liking.
Seafoam the idle settles at 600 to 700. Perhaps a good cleaning and base idle procedure would fix his idle to his liking.
-- Joe
Burning Brakes
Joined: Oct 2005
Posts: 798
Likes: 116
From: OAKLEY CA
Yes, my computer is relatively primative so it can be fooled into thinking it's at WOT even when it's not. That said, it still runs best overall when clean and set to factory specs. I guess those engineers tried all the different setings too.
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Melting Slicks
Joined: Feb 2006
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From: backwoods upstate ny
your tps is adjustable unless someone has substituted a latter type, non-slotted one--you must use the oem slotted one...get one from your local ac-delco parts if needed; we have seen bad new ones from several name sources recently....idle speed screw is adjustable-you can see the end of the adjuster in contact with the throttle arm--adjustment access is covered by a pressed in cover at the factory to prevent "tampering" for emissions---most covers disappeared long ago--you can carefully turn the adjuster where it is exposed at the throttle arm if you don't want to pry out the cover..
follow the complete idle set-up procedure to get the best results, leave any steps out and get mediocre operation....i've tried all, factory guys got it right on this.
no way is a new chip required
follow the complete idle set-up procedure to get the best results, leave any steps out and get mediocre operation....i've tried all, factory guys got it right on this.
no way is a new chip required
Last edited by redrose; Jun 5, 2006 at 03:02 PM.
Safety Car
Joined: May 2006
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From: Salem NH
Originally Posted by redrose
your tps is adjustable unless someone has substituted a latter type, non-slotted one--you must use the oem slotted one...get one from your local ac-delco parts if needed; we have seen bad new ones from several name sources recently....idle speed screw is adjustable-you can see the end of the adjuster in contact with the throttle arm--adjustment access is covered by a pressed in cover at the factory to prevent "tampering" for emissions---most covers disappeared long ago--you can carefully turn the adjuster where it is exposed at the throttle arm if you don't want to pry out the cover..
follow the complete idle set-up procedure to get the best results, leave any steps out and get mediocre operation....i've tried all, factory guys got it right on this.
no way is a new chip required
follow the complete idle set-up procedure to get the best results, leave any steps out and get mediocre operation....i've tried all, factory guys got it right on this.
no way is a new chip required
hahah.
The screw is for setting minimal idle speed, which is designed so you can get the idle stepper motor to 0 steps ad the absolute minimal idle.
You guys are silly
The idle speed is set in the chip, end of story. wanna set it to something absurd and have the ECM adjust everything from IAC to spark advance/retard to try and correct it? go right ahead!! There is a right way and a wrong way for everything.. I'm starting to notice a pattern around here.
-- Joe
Melting Slicks
Joined: Feb 2006
Posts: 2,753
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From: backwoods upstate ny
i could be wrong, wouldn't be the first time, just ask my wif...but the idle speed is NOT set by the chip....i've reset mine and a bunch of others....i've set my idle for 600, 700, 800, even 1000 during new engine break-in, using the adjusting screw and the full service manual procedure (which includes a step to drive the IAC to fully closed)...every time i have been rewarded by consistent idle at selected rpm, with no stalling at stop lights or other problems of any kind...just the facts,ma'am
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Joined: Sep 2000
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From: The Top of Utah
Originally Posted by redrose
i could be wrong, wouldn't be the first time, just ask my wif...but the idle speed is NOT set by the chip....
Originally Posted by redrose
no way is a new chip required
Originally Posted by anesthes
You guys are silly
The idle speed is set in the chip, end of story. wanna set it to something absurd and have the ECM adjust everything from IAC to spark advance/retard to try and correct it? go right ahead!! There is a right way and a wrong way for everything.. I'm starting to notice a pattern around here.
The idle speed is set in the chip, end of story. wanna set it to something absurd and have the ECM adjust everything from IAC to spark advance/retard to try and correct it? go right ahead!! There is a right way and a wrong way for everything.. I'm starting to notice a pattern around here.
The pattern isn't a new one, but it is great that others are paying attention and noticing.
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Team Owner
Joined: Mar 2000
Posts: 83,383
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From: Boston, MA
Originally Posted by redrose
i could be wrong, wouldn't be the first time, just ask my wif...but the idle speed is NOT set by the chip....i've reset mine and a bunch of others....i've set my idle for 600, 700, 800, even 1000 during new engine break-in, using the adjusting screw and the full service manual procedure (which includes a step to drive the IAC to fully closed)...every time i have been rewarded by consistent idle at selected rpm, with no stalling at stop lights or other problems of any kind...just the facts,ma'am
