Yellow Bullet Forums banner

1 - 20 of 23 Posts

·
Bracket racer
Joined
·
13,290 Posts
Discussion Starter · #1 · (Edited)
As many of you know, me and my friend done a head swap on his 96 LT1 Camaro. Also, he had the computer re-done and now the car won't shift....well, he sent the computer back and is supposed to get it back in a few days. While I had a scanner on the car we noticed the TPS voltage was only .057. It's supposed to be .067.....this car has a 58mm Holley throttle body on it that you can adjust the throttle blades with the adjustment screw. My question is will cracking the plates a little more increase the TPS voltage or do you have to modify it in some way?
 

·
Registered
Joined
·
1,292 Posts
Insted of cracking the throttle plates open more, I would see if the TPS is adjustable. Many are. Also, are you sure it's functioning properly?
 

·
Bracket racer
Joined
·
13,290 Posts
Discussion Starter · #3 ·
Insted of cracking the throttle plates open more, I would see if the TPS is adjustable. Many are. Also, are you sure it's functioning properly?
I don't know if the TPS is moveable or not, I'd have to look at it. It SHOULD be working properly...it was when he parked the car a month ago.
 

·
Bracket racer
Joined
·
13,290 Posts
Discussion Starter · #4 ·
Also, he's borrowing a stock computer to see if the car will shift....my concern is running a stock computer with a not stock engine....will it hurt it for 5 minutes?
 

·
Registered
Joined
·
1,023 Posts
If it has a stock cam I would adjust the minimum air rate (throttle plate screw) to factory setting.
Back the screw out, run it in until it JUST touches it's contact point, then go 1 1/2 turns. That should get you in the ballpark. If your close to .6, good. If it needs more air at idle, just adjust the screw and then you can elongate the screw holes if needed. But I was taught that anything under 1.00 volt the PCM will recognize as idle and as long as it's over 4 volts at WOT your good.
 

·
Bracket racer
Joined
·
13,290 Posts
Discussion Starter · #6 ·
If it has a stock cam I would adjust the minimum air rate (throttle plate screw) to factory setting.
Back the screw out, run it in until it JUST touches it's contact point, then go 1 1/2 turns. That should get you in the ballpark. If your close to .6, good. If it needs more air at idle, just adjust the screw and then you can elongate the screw holes if needed. But I was taught that anything under 1.00 volt the PCM will recognize as idle and as long as it's over 4 volts at WOT your good.
It has the GM LT4 "Hot cam." I'd say what you said is pretty close to where it's adjusted right now from eyeballing it the other day.
 

·
Registered
Joined
·
1,023 Posts
That cam may need at little more air at idle but you should be able to get it to idle nicely without a lot of trouble.
 

·
Bracket racer
Joined
·
13,290 Posts
Discussion Starter · #8 ·
One more question...does TPS voltage have anything to do with the transmission shifting? I've heard some say yes, some say no. I'm leaning towards no I just don't see how they're connected.
 

·
Bad Muther Fucka
Joined
·
845 Posts
As many of you know, me and my friend done a head swap on his 96 LT1 Camaro. Also, he had the computer re-done and now the car won't shift....well, he sent the computer back and is supposed to get it back in a few days. While I had a scanner on the car we noticed the TPS voltage was only .057. It's supposed to be .067.....this car has a 58mm Holley throttle body on it that you can adjust the throttle blades with the adjustment screw. My question is will cracking the plates a little more increase the TPS voltage or do you have to modify it in some way?

Did you use the original tps? or is a it new. If new where did you power it from? I wouldn't drive it much.
 

·
Registered
Joined
·
93 Posts
One more question...does TPS voltage have anything to do with the transmission shifting? I've heard some say yes, some say no. I'm leaning towards no I just don't see how they're connected.

I say yes. I had a 4L80e in my camaro and if it wasn't adjusted rite, it didn't shift rite.
 

·
Registered
Joined
·
3,480 Posts
If I'm not mistaken the obd 2 cars shift off of tps and mph.. I don't remember when they changed from obd 1 to obd 2... I know on a fox sometimes the tps wasn't slotted enough and you'd have to enlarge the holes...
 

·
Registered
Joined
·
48,027 Posts
Most TPS's are "adjustable", including the non-adjustable variety. Loosen (but do not remove) the two screws that hold the TPS on the throttle body. There is usually enough slack between the ID of the hole in the plastic, and the OD of the retainaing screws to rotate the TPS clockwise and counterclockwise a couple of degrees in each direction. Just a few degrees of rotation can make the difference. Usually, rotating the TPS clockwise will increase the voltage, counterclockwise will decrease the voltage. In some cases there may not be enough "slack" to play with. Use a very small "jewlers rat-tail file" to carefully elongate the holes in the plastic if you need too.
 

·
Bracket racer
Joined
·
13,290 Posts
Discussion Starter · #13 ·
Did you use the original tps? or is a it new. If new where did you power it from? I wouldn't drive it much.
The only thing that was changed on this car was the cylinder heads and it received bigger injectors. The other stuff was already on the car. He sent the PCM off to have it tuned before it was started....he got it back, and the car wouldn't shift. He has since sent the PCM back to get it re-flashed and re-tuned.
 

·
Bracket racer
Joined
·
13,290 Posts
Discussion Starter · #14 ·
If I'm not mistaken the obd 2 cars shift off of tps and mph.. I don't remember when they changed from obd 1 to obd 2... I know on a fox sometimes the tps wasn't slotted enough and you'd have to enlarge the holes...
Hmmm....interesting. How would a higher flowing set of heads and a bigger set of injectors affect TPS voltage?!
 

·
Bracket racer
Joined
·
13,290 Posts
Discussion Starter · #15 ·
Most TPS's are "adjustable", including the non-adjustable variety. Loosen (but do not remove) the two screws that hold the TPS on the throttle body. There is usually enough slack between the ID of the hole in the plastic, and the OD of the retainaing screws to rotate the TPS clockwise and counterclockwise a couple of degrees in each direction. Just a few degrees of rotation can make the difference. Usually, rotating the TPS clockwise will increase the voltage, counterclockwise will decrease the voltage. In some cases there may not be enough "slack" to play with. Use a very small "jewlers rat-tail file" to carefully elongate the holes in the plastic if you need too.
Cool thanks! At least we know how to adjust it now without making too big of a mess.
 

·
Registered
Joined
·
2 Posts
Hey guys, I'm the owner of the car. This TPS is adjustable but only to a certain point then you have to enlarge the holes. I figured the TPS could mess up the shifts but I didn't think it would keep it from shifting completely.
 

·
Registered
Joined
·
49 Posts
obd 2 cars shift off tps voltage engine speed and map sensor voltage so the tps could effect shifting but i don't think that small of difference would effect the shift pattern
 

·
Registered
Joined
·
926 Posts
If I'm not mistaken the obd 2 cars shift off of tps and mph.. I don't remember when they changed from obd 1 to obd 2... I know on a fox sometimes the tps wasn't slotted enough and you'd have to enlarge the holes...
I don't know shit about GM TPS sensors but on a ford (fox specific) the TPS is NON ADJUSTABLE. Everytime you turn the key the ECM resets TPS voltage. If it makes you feel better to adjust it have at it. Yes you can twist it/slot the sensor. Old wives tales, much like the one where married women love their husbands...
 

·
Registered
Joined
·
1,023 Posts
If you still have a scanner check your throttle % key on/engine off. It should be 0% and tps at about .6. If I remember correctly the PCM is more concerned about percentage rather then the actual voltage.
 

·
Bracket racer
Joined
·
13,290 Posts
Discussion Starter · #20 ·
If you still have a scanner check your throttle % key on/engine off. It should be 0% and tps at about .6. If I remember correctly the PCM is more concerned about percentage rather then the actual voltage.
Cool I'll have to check that out. I wanna say it was zero but I'm not positive.
 
1 - 20 of 23 Posts
Top