TPS won't reset to 0%
As robust as these PCMs seem to be I would almost say to try a different one at this point just to eliminate that possibility. Although that is easy for me to do because I have full model year licences on almost everything 96-07 MY so it doesn't cost me anything to license another PCM.
I had a similar problem and had to replace the connector because the pins inside were bent and not making the best contact. There is an updated part that keeps stress off the pins.
An easy way to check this would be to gently jiggle the connector when it's plugged in and see if the reading goes erratic.
Mine would show 7% at idle, but 0% when powered off. Why? I have no idea. But it works perfectly now and no more 1000rpm idle.
An easy way to check this would be to gently jiggle the connector when it's plugged in and see if the reading goes erratic.
Mine would show 7% at idle, but 0% when powered off. Why? I have no idea. But it works perfectly now and no more 1000rpm idle.
Are you sure you don't have a weak throttle body return spring and the manifold vacuum is not pulling the blade open a little? Just a thought. But you would probably see that in a greater change in the TPS output voltage if that was happening.
Thread Starter
Teching In
Joined: Oct 2010
Posts: 20
Likes: 0
From: Memphis, TN
2xLS1 thank you for ur help, it was a grounding issue, after trying everything I foun out that when I did this engine swap I never ground the PCM's 4 grounds properly, car runs good and stays at 0.0% or 0.4% which is right where it's suppose to be, again thanks for ur help!!
Thread Starter
Teching In
Joined: Oct 2010
Posts: 20
Likes: 0
From: Memphis, TN
Ok guys finally after chasing this TPS problem, I found what was wrong with it, my PCM wasn't grounded properly, if anybody did a swap and has this problem make sure all you're PCM grounds are grounded to the good ground, my engine came out of 2000 TA and ground pins are on the blue connector #1 and #40, on the red connector are also #1 and #40, thank you guys all for the help I really appreciated, now I can get my car tuned and enjoy my 383 Stroker!!!!! :-)))
LS1 Tech Stories
The Best V8 Stories One Small Block at Time
6 Common C5 Corvette Failures and What's Involved In Repairing Them
Pouria Savadkouei
Retro Modern Bandit Pontiac Trans AM Comes With Burt Reynolds' Autograph
Verdad Gallardo
Top 10 Greatest Cadillac V Series Performance Models Ever, Ranked
Pouria Savadkouei
Top 10 Most Powerful Chevy Trucks Ever Made!
Hennessey's New Supercharged Silverado ZR2 Has 700 HP
Verdad Gallardo
Coachbuilt N2A Anteros Is an LS2-Powered C6 Corvette In Italian Clothes
Verdad Gallardo
Awesome K5 Blazer Restomod Comes With C7 Corvette Power
Verdad Gallardo
10 Camaros You Should Never Buy
10 LS Engine Myths That Refuse to Die
Verdad Gallardo
Launching!
Joined: Mar 2009
Posts: 274
Likes: 0
From: Weatherford Tx 76085 corner of N. Hwy 51 and 150 Green branch Rd.
Thanks guys who chimed in to help. Got same problem with mine and about to tackle it on. This is on an LTX 24x conversion which is same pcm. I was going to try running new grounds anyways. Reading this just confims that it is the best step to take on it first. Thanks for replying back with good results.
I'm having the same issue.
In HP tuners while at idle:
Throttle pos sensor: 0.73v
Throttle desired position: 0.6%
Throttle position SAE: 0.4%
Idle Air control position 35
Idle Air control desired position 32
Already tried the TPS reset.
Where on the car are the 4 specific grounds to the PCM. I can check for good ground right at the pins on the ecm, but where are the specific points on the chassis?
#1: Back of passenger side cylinder head.
#2: Passenger side of block.
#3: 3 ground wires on the back of the drivers side head.
#4: under the bracket for the air box assembly. (can cause all kinds of light problems)
#5: cluster of ground wires on the lower ds pillar, close to the door pushbutton for the interior light.
#6: Grounding strap from just behind alternator. (PS fluid just loves to reek havoc in that area)
In HP tuners while at idle:
Throttle pos sensor: 0.73v
Throttle desired position: 0.6%
Throttle position SAE: 0.4%
Idle Air control position 35
Idle Air control desired position 32
Already tried the TPS reset.
Where on the car are the 4 specific grounds to the PCM. I can check for good ground right at the pins on the ecm, but where are the specific points on the chassis?
#1: Back of passenger side cylinder head.
#2: Passenger side of block.
#3: 3 ground wires on the back of the drivers side head.
#4: under the bracket for the air box assembly. (can cause all kinds of light problems)
#5: cluster of ground wires on the lower ds pillar, close to the door pushbutton for the interior light.
#6: Grounding strap from just behind alternator. (PS fluid just loves to reek havoc in that area)
Last edited by 5.7stroker; May 10, 2017 at 11:43 AM.
I'm getting 0.71v at 0.4% on TPS when closed and 4.53v at 100% when TB is fully open at 90 degrees, both by pedal and by moving TB by hand.
After resetting the TPS, it goes to 0v but then goes right back to 0.4% as soon as the car is started.
I checked the tps wires on the harness tps harness itself, an I get the 0.73v and 4.55v. With the car off, and tps harness unplugged, the ground wiring on the harness has 0 resistance. When the car is in run pos with engine off, that same ground wire shows 0.014 resistance. This is with black lead on the multi connected direct to battery. When cranking to put load, it shows 0.100 - 0.200 resistance.
I checked pins 1 and 40 on both ecm harnesses and the resistance is 0 with the car turned off. This is with black lead connected to battery and red lead connected to a paperclip shoved into the red/blue ecm harness holes.
I want to get the tps to read 0%.
Speed density tune, PTM 92mm TB, has small hole drilled into it.
If I try to turn the set screw, voltage at say 0.55v causes TPS to be at 3.0%. Going back to 0.73v on the set screw the best I can get the TPS while car is running is 0.4%, and this is with resetting the TPS properly back to 0 after adjustments.
After resetting the TPS, it goes to 0v but then goes right back to 0.4% as soon as the car is started.
I checked the tps wires on the harness tps harness itself, an I get the 0.73v and 4.55v. With the car off, and tps harness unplugged, the ground wiring on the harness has 0 resistance. When the car is in run pos with engine off, that same ground wire shows 0.014 resistance. This is with black lead on the multi connected direct to battery. When cranking to put load, it shows 0.100 - 0.200 resistance.
I checked pins 1 and 40 on both ecm harnesses and the resistance is 0 with the car turned off. This is with black lead connected to battery and red lead connected to a paperclip shoved into the red/blue ecm harness holes.
I want to get the tps to read 0%.
Speed density tune, PTM 92mm TB, has small hole drilled into it.
If I try to turn the set screw, voltage at say 0.55v causes TPS to be at 3.0%. Going back to 0.73v on the set screw the best I can get the TPS while car is running is 0.4%, and this is with resetting the TPS properly back to 0 after adjustments.
Last edited by 5.7stroker; May 10, 2017 at 02:05 PM.
I'm getting 0.71v at 0.4% on TPS when closed and 4.53v at 100% when TB is fully open at 90 degrees, both by pedal and by moving TB by hand.
After resetting the TPS, it goes to 0v but then goes right back to 0.4% as soon as the car is started.
I checked the tps wires on the harness tps harness itself, an I get the 0.73v and 4.55v. With the car off, and tps harness unplugged, the ground wiring on the harness has 0 resistance. When the car is in run pos with engine off, that same ground wire shows 0.014 resistance. This is with black lead on the multi connected direct to battery. When cranking to put load, it shows 0.100 - 0.200 resistance.
I checked pins 1 and 40 on both ecm harnesses and the resistance is 0 with the car turned off. This is with black lead connected to battery and red lead connected to a paperclip shoved into the red/blue ecm harness holes.
I want to get the tps to read 0%.
Speed density tune, PTM 92mm TB, has small hole drilled into it.
If I try to turn the set screw, voltage at say 0.55v causes TPS to be at 3.0%. Going back to 0.73v on the set screw the best I can get the TPS while car is running is 0.4%, and this is with resetting the TPS properly back to 0 after adjustments.
After resetting the TPS, it goes to 0v but then goes right back to 0.4% as soon as the car is started.
I checked the tps wires on the harness tps harness itself, an I get the 0.73v and 4.55v. With the car off, and tps harness unplugged, the ground wiring on the harness has 0 resistance. When the car is in run pos with engine off, that same ground wire shows 0.014 resistance. This is with black lead on the multi connected direct to battery. When cranking to put load, it shows 0.100 - 0.200 resistance.
I checked pins 1 and 40 on both ecm harnesses and the resistance is 0 with the car turned off. This is with black lead connected to battery and red lead connected to a paperclip shoved into the red/blue ecm harness holes.
I want to get the tps to read 0%.
Speed density tune, PTM 92mm TB, has small hole drilled into it.
If I try to turn the set screw, voltage at say 0.55v causes TPS to be at 3.0%. Going back to 0.73v on the set screw the best I can get the TPS while car is running is 0.4%, and this is with resetting the TPS properly back to 0 after adjustments.
