TPS Adjustment
Thread Starter
Racer
Joined: Mar 2004
Posts: 305
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From: Houston Texas
TPS Adjustment
To anyone that has ever replaced the Throttle Position Sensor on a 1985 Coupe -
Where the two screws go, does the new TPS have slots, so that you can adjust the TPS?
I am asking because I do not know if the TPS that I removed last week was the original one. The old one and the one that I installed had the slots for adjustment. The chevy dealership here in Houston told me that the one that they sell doesn't have slots, just two holes. That way, the TPS can not be adjusted. (At least he thinks it only has two holes. They don't have one in stock right now, so they can't verify, one way or the other.)
I was sure that I adjusted it correctly. I set it to 0.525. Even rechecked it, once I had tightened it.
Any thoughts???
Where the two screws go, does the new TPS have slots, so that you can adjust the TPS?
I am asking because I do not know if the TPS that I removed last week was the original one. The old one and the one that I installed had the slots for adjustment. The chevy dealership here in Houston told me that the one that they sell doesn't have slots, just two holes. That way, the TPS can not be adjusted. (At least he thinks it only has two holes. They don't have one in stock right now, so they can't verify, one way or the other.)
I was sure that I adjusted it correctly. I set it to 0.525. Even rechecked it, once I had tightened it.
Any thoughts???
Drifting
Joined: Nov 2000
Posts: 1,428
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From: Jacksonville FL
Thread Starter
Racer
Joined: Mar 2004
Posts: 305
Likes: 0
From: Houston Texas
I read your tech tip. It was very informative.
Will it make a difference if my TPS is set at 0.525?
Also, my engine is running rough right now. I am not sure it will idle at 400 rpms.
Will it make a difference if my TPS is set at 0.525?
Also, my engine is running rough right now. I am not sure it will idle at 400 rpms.
Le Mans Master
Joined: May 2004
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From: Hellinois
Finalist 2020 C4 of the Year - Modified
Originally Posted by 8vett5
85 was non adjusable, two holes 
Team Owner
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From: Freedom is never more than one generation away from extinction.
St. Jude '03 thru '24
Originally Posted by Moxxi
Will it make a difference if my TPS is set at 0.525?
Set the TPS with the engine at idle at 0.54. Thats all you have to do. The TPS simply tells the ECM were the throttle position is.
Rough idle is a product of many different things that may play a part. Dirty TB, dirty injectors, a vaccum leak, old plugs and on and on.
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Instructor
Joined: Nov 2001
Posts: 141
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From: Renton WA
I have an 85. Definately have to adjust TPS.
I adjust mine to whatever I feel like. I get 28-30 mpg on the freeway.
I know something.
But factory setting is .54 volts. Hook up scanner or Diacom. EASY to adjust.
I adjust mine to whatever I feel like. I get 28-30 mpg on the freeway.
I know something.
But factory setting is .54 volts. Hook up scanner or Diacom. EASY to adjust.
Le Mans Master
Joined: Feb 2005
Posts: 5,146
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From: The Motor City
What I have found out is some have slots some do not, my 90 had 2 holes. I think that should really be done after, and in conguntion with adjusting the IAC (min. air adjustment).
After min. air adjustment (IAC out of the picture first) then reconnected, checking the TPS on mine showed .64 volts, took it of slotted it with a dremel carbide tip and re-set. When I set it without running at .54 when running it showed a gain on a scanner to .56. those numbers are all in range to spec however +-6, regardless will still show 0 throttle angle when running at idle.
After min. air adjustment (IAC out of the picture first) then reconnected, checking the TPS on mine showed .64 volts, took it of slotted it with a dremel carbide tip and re-set. When I set it without running at .54 when running it showed a gain on a scanner to .56. those numbers are all in range to spec however +-6, regardless will still show 0 throttle angle when running at idle.
Last edited by mseven; Feb 21, 2006 at 07:43 AM.
Thread Starter
Racer
Joined: Mar 2004
Posts: 305
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From: Houston Texas
Originally Posted by JrRifleCoach
Rough idle is a product of many different things that may play a part. Dirty TB, dirty injectors, a vaccum leak, old plugs and on and on.
Le Mans Master
Joined: Feb 2000
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From: Kempner Texas
The spec for 86 is .54 volts +/- .075 This means that any setting from .615 to .465 is still within spec.
Most posts I've read on this and other Forums and from my own personal experience in trying different settings shows that a slightly higher setting - in the range of .61 - gives the best throttle response and performance.
I've gone as high as .65 with no really noticable downside. Chances are that anything much higher than .65 will cause a high TPS voltage SES code to set.
Try different settings and see which one you like best.
Jake
Most posts I've read on this and other Forums and from my own personal experience in trying different settings shows that a slightly higher setting - in the range of .61 - gives the best throttle response and performance.
I've gone as high as .65 with no really noticable downside. Chances are that anything much higher than .65 will cause a high TPS voltage SES code to set.
Try different settings and see which one you like best.
Jake
Race Director
Joined: Sep 2000
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From: The Top of Utah
UNBELIEVABLE!!!
I cannot conceive of all the wrong answers associated with such a simple question. The 1984 through 1989s had adjustable TPSs. From 1990 and up, they are fixed. The ECM reads the minimum setting and accepts and establishes that as closed throttle.
The IAC adjustment is easily made with a volt meter and there is no reason for the engine to be running. My FSM says key, "On", engine, "Off".
Much higher than spec settings makes the throttle more sensitive. The additional sensitivity, and corresponding perception of throttle response MAY be mistaken for an increase in performance or power. It isn't.
RACE ON!!!
I cannot conceive of all the wrong answers associated with such a simple question. The 1984 through 1989s had adjustable TPSs. From 1990 and up, they are fixed. The ECM reads the minimum setting and accepts and establishes that as closed throttle.
The IAC adjustment is easily made with a volt meter and there is no reason for the engine to be running. My FSM says key, "On", engine, "Off".
Much higher than spec settings makes the throttle more sensitive. The additional sensitivity, and corresponding perception of throttle response MAY be mistaken for an increase in performance or power. It isn't.
RACE ON!!!
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
Originally Posted by CFI-EFI
The ECM reads the minimum setting and accepts and establishes that as closed throttle.
The IAC adjustment is easily made with a volt meter and there is no reason for the engine to be running. My FSM says key, "On", engine, "Off".
Much higher than spec settings makes the throttle more sensitive. The additional sensitivity, and corresponding perception of throttle response MAY be mistaken for an increase in performance or power. It isn't.
RACE ON!!!
The IAC adjustment is easily made with a volt meter and there is no reason for the engine to be running. My FSM says key, "On", engine, "Off".
Much higher than spec settings makes the throttle more sensitive. The additional sensitivity, and corresponding perception of throttle response MAY be mistaken for an increase in performance or power. It isn't.
RACE ON!!!
......I agree with what you have said (said similar earlier).Jake,
I am interested in knowing how that by increasing voltage setting at the TPS would create throttle response?
What action is the ECM taking when seeing a higher voltage reading?
Instructor
Joined: Nov 2001
Posts: 141
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From: Renton WA
CFI-EFI:
I mean no disrespect, but changing the TPS voltage does do something. It is not negated and zeroed out at each restart.
If you don't believe me, then I guess TPIS are a bunch of crackpots.
And Insider Hints is a book about of lies.
It does make a difference on MAF L98 cars. Changes mixture.
I mean no disrespect, but changing the TPS voltage does do something. It is not negated and zeroed out at each restart.
If you don't believe me, then I guess TPIS are a bunch of crackpots.
And Insider Hints is a book about of lies.
It does make a difference on MAF L98 cars. Changes mixture.
Le Mans Master
Joined: Feb 2005
Posts: 5,146
Likes: 3
From: The Motor City
Originally Posted by Duntov85
CFI-EFI:
I mean no disrespect, but changing the TPS voltage does do something. It is not negated and zeroed out at each restart.
If you don't believe me, then I guess TPIS are a bunch of crackpots.
And Insider Hints is a book about of lies.
It does make a difference on MAF L98 cars. Changes mixture.
I mean no disrespect, but changing the TPS voltage does do something. It is not negated and zeroed out at each restart.
If you don't believe me, then I guess TPIS are a bunch of crackpots.
And Insider Hints is a book about of lies.
It does make a difference on MAF L98 cars. Changes mixture.
Last edited by mseven; Feb 22, 2006 at 07:14 AM.
Race Director
Joined: Sep 2000
Posts: 17,298
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From: The Top of Utah
Originally Posted by mseven
I know you meant TPS ......I agree with what you have said (said similar earlier).
......I agree with what you have said (said similar earlier).
Originally Posted by Duntov85
CFI-EFI:
I mean no disrespect, but changing the TPS voltage does do something. It is not negated and zeroed out at each restart.
I mean no disrespect, but changing the TPS voltage does do something. It is not negated and zeroed out at each restart.
Originally Posted by Duntov85
If you don't believe me, then I guess TPIS are a bunch of crackpots. And Insider Hints is a book about of lies.
I stand by my position. Adjusting a non-adjustable (fixed) TPS on a car built to use it, will have no effect on performance.
RACE ON!!!