86 vette tps question
Thread Starter
Instructor
Joined: Feb 2010
Posts: 108
Likes: 0
From: Bay Area California
86 vette tps question
I have a 1986 vin 8 L98, that is giving me a code 21.
the book says it's because the tps was above 4.5 volts
at any time. I thought the setting was .54 volts min
and 5.0 volts at WOT. is this true? if so why would I
be getting this code?
Thanks for the help!
the book says it's because the tps was above 4.5 volts
at any time. I thought the setting was .54 volts min
and 5.0 volts at WOT. is this true? if so why would I
be getting this code?
Thanks for the help!
Racer
Joined: Aug 2009
Posts: 496
Likes: 4
From: Cordova TN
Thread Starter
Instructor
Joined: Feb 2010
Posts: 108
Likes: 0
From: Bay Area California
Thanks for the quick response !
I've read this article before, and followed this procedure,
but, what should the tps voltage be at wot ?
4.5 volts OR 5.0 volts?
the manual says 5.0 volts, but code 21 says tps voltage
was above 4.5 volts at any time, I'm still confused.
I've read this article before, and followed this procedure,
but, what should the tps voltage be at wot ?
4.5 volts OR 5.0 volts?
the manual says 5.0 volts, but code 21 says tps voltage
was above 4.5 volts at any time, I'm still confused.
Racer
Joined: Aug 2009
Posts: 496
Likes: 4
From: Cordova TN
It has been a while since I set my 89 Formula's tps but I think 5 is a bit high. Somewhere around 4.5 is what you want to see.
Looking on the thirdgen.org website tells me anything over 4 is cool but needless to say you don't want it going over 4.5.
Looking on the thirdgen.org website tells me anything over 4 is cool but needless to say you don't want it going over 4.5.
Last edited by megtom2; Feb 18, 2010 at 12:02 AM.
Team Owner
Joined: Jan 2003
Posts: 20,305
Likes: 240
From: Summerland B.C. Canada
Team Owner
Joined: Jan 2003
Posts: 20,305
Likes: 240
From: Summerland B.C. Canada
Thread Starter
Instructor
Joined: Feb 2010
Posts: 108
Likes: 0
From: Bay Area California
Thank you all for you're help, I saw the check engine light come
on when i was driving it, and held it at wot for 5 sec. the
check engine light went off on it's own after 20 sec.
I'll set the tps at .54 volts and 4.5 volts WOT and see
what happens !
Thanks again !
on when i was driving it, and held it at wot for 5 sec. the
check engine light went off on it's own after 20 sec.
I'll set the tps at .54 volts and 4.5 volts WOT and see
what happens !
Thanks again !
Le Mans Master
Joined: Sep 2006
Posts: 6,050
Likes: 147
From: Phoenix AZ
2021 C4 of the Year - Modified Finalist
I don't think you can set the WOT, just set the idle at .54, and them MAKE SURE it doesn't go over 4.5 at wot.
i wouldn't worry about the top voltage at this point if it sets and runs without a check engine light.
i wouldn't worry about the top voltage at this point if it sets and runs without a check engine light.
Corvette Stories
The Best of Corvette for Corvette Enthusiasts
Top 10 Most Explosive Corvettes Ever Made: Power-to-Weight Ratio Ranked!
Joe Kucinski
150 hp to 1,250 hp: Every Corvette Generation Compared by the Specs That Matter
Joe Kucinski
8 Coolest Corvette Pace Cars (and Replicas) of All Time
Verdad Gallardo
Top 10 Corvette Engines RANKED by Peak Torque (70+ Years of Muscle!)
Joe Kucinski
Corvette ZR1X Will Be Pacing the Indy 500, And Could Probably Race, Too!
Verdad Gallardo
Top 10 Corvettes Coming to Mecum Indy 2026!
Brett Foote
Top 10 C9 Corvette MUST-HAVES to Fix These C8 Generation Flaws!
Michael S. Palmer
10 Revolutionary 'Corvette Firsts' Most People Don't Know
Joe Kucinski
5 Reasons to Upgrade to an LS6-Powered Corvette; 5 Reasons to Stay LT2
Michael S. Palmer
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Going from memory on this since it's been a few years since I had a 86.
You have a range within which the voltage is correct. It's .54 (+/- .075). That's measured with the engine "OFF", ignition key "ON". That's how the TPS voltage is set; OFF/ON.
Many guys shoot for the high side, like .61 or sometimes even more. If you go too high, a code will set.
Voltage above 4.0 tells the ECM that you're at WOT (even if you're not) and causes the ECM to enter Power Enrichment Mode; AKA PE Mode.
Using a digital volt meter, you can check your TPS by slowly opening the butterflies while watching the voltage readings increase. Numbers should NOT suddenly jump/skip. They should increase at the rate you're opening the throttle. Do it slowly.
Hope this helps.
Jake
You have a range within which the voltage is correct. It's .54 (+/- .075). That's measured with the engine "OFF", ignition key "ON". That's how the TPS voltage is set; OFF/ON.
Many guys shoot for the high side, like .61 or sometimes even more. If you go too high, a code will set.
Voltage above 4.0 tells the ECM that you're at WOT (even if you're not) and causes the ECM to enter Power Enrichment Mode; AKA PE Mode.
Using a digital volt meter, you can check your TPS by slowly opening the butterflies while watching the voltage readings increase. Numbers should NOT suddenly jump/skip. They should increase at the rate you're opening the throttle. Do it slowly.
Hope this helps.
Jake
