Is the 96's TPS Voltage Adjustable?
Thread Starter
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Is the 96's TPS Voltage Adjustable?
I'm receiving conflicting information on this. One persons says it's adjustable but others have said it isn't and that it's automatically controlled by the PCM.
Who's right?
Thanks,
Jake
West Point ROCKS!
Who's right?
Thanks,
Jake
West Point ROCKS!
Thread Starter
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
That's pretty much what I've read, except for the part about when GM stopped using the adjustable ones.
However, I wanted to get several replies supporting my position before I go up against a Moderator and an Administrator on another forum. We're trying to help a member with a high idle problem after installing an aftermarket TB.
They've got me back into a corner and I have, except for you, no back-up. LOL
Jake
West Point ROCKS!
However, I wanted to get several replies supporting my position before I go up against a Moderator and an Administrator on another forum. We're trying to help a member with a high idle problem after installing an aftermarket TB.
They've got me back into a corner and I have, except for you, no back-up. LOL
Jake
West Point ROCKS!
Thread Starter
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Well, the war's still raging, but I'm sticking to my guns; that the 94/95/96 TPS is not adjustable.
One of the guys sent me a link to GolenEngines which shows a procedure, like you did, to elongate the slot in order to provide some adjustablilty.
But I still feel that the system was designed to be non-adjustable, but I may lose on this for technical reasons.
So I can pass it along, without identifying you of course, what effect did the elongating mod make?
Any noticable improvement/difference?
Jake
West Point ROCKS!
Melting Slicks
Joined: Oct 2004
Posts: 2,510
Likes: 4
From: Austin Texas
Thanks for that info.
Well, the war's still raging, but I'm sticking to my guns; that the 94/95/96 TPS is not adjustable.
One of the guys sent me a link to GolenEngines which shows a procedure, like you did, to elongate the slot in order to provide some adjustablilty.
But I still feel that the system was designed to be non-adjustable, but I may lose on this for technical reasons.
So I can pass it along, without identifying you of course, what effect did the elongating mod make?
Any noticable improvement/difference?
Jake
West Point ROCKS!
Well, the war's still raging, but I'm sticking to my guns; that the 94/95/96 TPS is not adjustable.
One of the guys sent me a link to GolenEngines which shows a procedure, like you did, to elongate the slot in order to provide some adjustablilty.
But I still feel that the system was designed to be non-adjustable, but I may lose on this for technical reasons.
So I can pass it along, without identifying you of course, what effect did the elongating mod make?
Any noticable improvement/difference?
Jake
West Point ROCKS!
Last edited by MikeC4; Mar 10, 2009 at 09:17 PM.
Le Mans Master
Joined: Feb 1999
Posts: 9,939
Likes: 38
From: South Carolina
St. Jude Donor '03 & '05
92-96 is not adjustable. I drilled mine to allow changes at idle, due to aftermarket throttle body not being perfect. But once an LTx engine sets itself up, the tps should set back to zero.
Melting Slicks
Joined: Dec 1999
Posts: 2,816
Likes: 2
From: Austin, TX
As per previous posts, they are not adjustable, but you can add adjustability by elongating the holes.
Those who say the computer will automatically adjust are partially right. The computer will reset itself to 0% throttle each time you start the car, but only to a point. For example on some aftermarket throttlebodies, the TPS is too far off and the computer may 'think' you're at 10% throttle when you're really at 0%. That's when you have no other option but to elongate the holes.
Those who say the computer will automatically adjust are partially right. The computer will reset itself to 0% throttle each time you start the car, but only to a point. For example on some aftermarket throttlebodies, the TPS is too far off and the computer may 'think' you're at 10% throttle when you're really at 0%. That's when you have no other option but to elongate the holes.
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Burning Brakes
Joined: Nov 2006
Posts: 1,102
Likes: 1
From: Portsmouth Virginia 396LT4 435RWHP/400RWTQ Best so far 11.26 @ 123mph
Jake,
Eckler's offers an adjustable TPS sensor if interested.
PN# 41422 is for the 94-96. It comes with an adjusting kit with a jumper connector. I have used these on my 95 and 96 for about 6 years now. The jumper definitely makes setting it easier. Elongating the factory slot is about the only other option. I have found that the factory slot/ hole only has a few hundreths of a volt adjustment due to the existing screw/hole clearance but for general purposes it is basically non-ajustable.
Rick
Eckler's offers an adjustable TPS sensor if interested.
PN# 41422 is for the 94-96. It comes with an adjusting kit with a jumper connector. I have used these on my 95 and 96 for about 6 years now. The jumper definitely makes setting it easier. Elongating the factory slot is about the only other option. I have found that the factory slot/ hole only has a few hundreths of a volt adjustment due to the existing screw/hole clearance but for general purposes it is basically non-ajustable.
Rick
Last edited by PDQUIK95; Mar 11, 2009 at 08:13 AM. Reason: add
Race Director
Joined: Apr 2000
Posts: 15,344
Likes: 4,009
From: Texas
Keep in mind that the reason the TPS was adjustable was so that the ECM knew where 0% throttle was based on TPS voltage.
For the non-adjustable TPS cars, the ECM (PCM for the late C4s) looks at anything less than ~0.9 volts and "self zeros".
For the non-adjustable TPS cars, the ECM (PCM for the late C4s) looks at anything less than ~0.9 volts and "self zeros".
Burning Brakes
Joined: Nov 2006
Posts: 1,102
Likes: 1
From: Portsmouth Virginia 396LT4 435RWHP/400RWTQ Best so far 11.26 @ 123mph
Agree,
The only real reason or benefit to an ajustable TPS sensor is to be able to advance the voltage signal sent to the PCM for earlier and quicker start of WOT application.The PCM does use the actual amount of voltage input for WOT. For closed throttle the PCM does zero the given voltage. With an adjustable, there is also a limit to how far you can advance the voltage signal before it causes an error code.I have tried this and it seems to error in the PCM at about .68 at closed throttle when trying to achieve a full 5 volts at WOT. I wound up with about .63at closed and 4.8 at WOT.
Rick
The only real reason or benefit to an ajustable TPS sensor is to be able to advance the voltage signal sent to the PCM for earlier and quicker start of WOT application.The PCM does use the actual amount of voltage input for WOT. For closed throttle the PCM does zero the given voltage. With an adjustable, there is also a limit to how far you can advance the voltage signal before it causes an error code.I have tried this and it seems to error in the PCM at about .68 at closed throttle when trying to achieve a full 5 volts at WOT. I wound up with about .63at closed and 4.8 at WOT.
Rick
Thread Starter
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
I just came across this months' old thread I started; I forgot I started it. I apologize to those who responded to it for taking so long to offer my thanks for their feedback.
1996 LT1: Let me add a couple of more TPS/IAC feed-back questions (at times like this I sure miss FSM Book 2); Which two wires are we using to check the TPS voltage?
I know on L98s it was the top and middle wires, but those TPS' were mounted differently than on the 96 LT1 engines.
Also, I assume that re-setting the IAC is the same as in earlier engines - paper clip in the ALDL, key ON, wait, unplug IAC, remove clip, start and idle engine, set idle speed, shut down, re-plug IAC. Right?
I want to check my son's TPS voltage and re-set the IAC now that his engine is back in and running with the new cam and heads.
Thanks - this time in advance, LOL.
Jake
West Point ROCKS!
1996 LT1: Let me add a couple of more TPS/IAC feed-back questions (at times like this I sure miss FSM Book 2); Which two wires are we using to check the TPS voltage?
I know on L98s it was the top and middle wires, but those TPS' were mounted differently than on the 96 LT1 engines.
Also, I assume that re-setting the IAC is the same as in earlier engines - paper clip in the ALDL, key ON, wait, unplug IAC, remove clip, start and idle engine, set idle speed, shut down, re-plug IAC. Right?
I want to check my son's TPS voltage and re-set the IAC now that his engine is back in and running with the new cam and heads.
Thanks - this time in advance, LOL.
Jake
West Point ROCKS!
Thread Starter
Le Mans Master
Joined: Feb 2000
Posts: 9,715
Likes: 27
From: Kempner Texas
Okay, since Golen Engines says to elongate the TPS mounting holes and adjust the reading to .67 I thought I'd give it a try just to see.
So following Golen's directions, I did that and, using the blue wire, set my son's at .67 last evening. I haven't driven his car yet, so I can't say if there's any difference yet.
Thanks again,
Jake
West Point ROCKS!
So following Golen's directions, I did that and, using the blue wire, set my son's at .67 last evening. I haven't driven his car yet, so I can't say if there's any difference yet.
Thanks again,
Jake
West Point ROCKS!
