Checking TPS voltage
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
I find this interesting I just changed mine and it is not adjustable any way.Just twisted it into position to spring load it put the screws in and away I went It runs a little better I though I had a low rpm dead spot around 1500rpms and it seems to be gone now.
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
Originally Posted by Redeasysport
I find this interesting I just changed mine and it is not adjustable any way.Just twisted it into position to spring load it put the screws in and away I went It runs a little better I though I had a low rpm dead spot around 1500rpms and it seems to be gone now.
just loosen the two small torx head screws on the side to adjust....it is spring loaded, but still needs to be adjusted
BTW what I did was to use my Autotap......with the accelerator at WOT I turned the TPS until Autotap showed 100% throttle.....then tightened the 2 mounting screws..
then verified 0% throttle position....just to be sure..
Last edited by LT4BUD; Jul 12, 2005 at 08:20 AM.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Originally Posted by LT4BUD
If you look you will see the "mounting" holes are actually slots, not holes....this allows you to turn theTPS into proper position.....for sure mine, a 96 LT, actually an Edebrock, is adjustable...it came from Edelbrock pre-adjusted....
just loosen the two small torx head screws on the side to adjust....it is spring loaded, but still needs to be adjusted
BTW what I did was to use my Autotap......with the accelerator at WOT I turned the TPS until Autotap showed 100% throttle.....then tightened the 2 mounting screws..
then verified 0% throttle position....just to be sure..
just loosen the two small torx head screws on the side to adjust....it is spring loaded, but still needs to be adjusted
BTW what I did was to use my Autotap......with the accelerator at WOT I turned the TPS until Autotap showed 100% throttle.....then tightened the 2 mounting screws..
then verified 0% throttle position....just to be sure..
I know you can use a couple of straight pins and a VOM to check the voltage should be around 5.4V right?
Le Mans Master
Joined: Dec 2000
Posts: 7,839
Likes: 22
From: San Diego, Ca
Don't know about the aftermarket, but I'm pretty sure everything GM has built since '92 isn't adjustable. .62 volts is where they usually spec at. Use a scanner, but realistically, absent a code, there's little to check.
Drifting
Joined: Mar 2005
Posts: 1,923
Likes: 0
From: GA
Originally Posted by SunCr
Don't know about the aftermarket, but I'm pretty sure everything GM has built since '92 isn't adjustable. .62 volts is where they usually spec at. Use a scanner, but realistically, absent a code, there's little to check.
You are absolutely correct. The ECM "zeros" it out on its own.
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
Originally Posted by Redeasysport
Thanks Bud I will check that but the car runs fine as it is I am afraid if I take it off I wont get Lucky I know you can use a couple of straight pins and a VOM to check the voltage should be around 5.4V right?
I know you can use a couple of straight pins and a VOM to check the voltage should be around 5.4V right?...and mine did start and at least idled fine out of adjustment....just don't ask me how it got out of adjustment
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Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Originally Posted by SunCr
Don't know about the aftermarket, but I'm pretty sure everything GM has built since '92 isn't adjustable. .62 volts is where they usually spec at. Use a scanner, but realistically, absent a code, there's little to check.
It did not look adjustable to me either.6.2V is what I will check for.
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 32
From: The Top of Utah
Originally Posted by Redeasysport
Ok so now I am confused It did not look adjustable to me either.6.2V is what I will check for.
It did not look adjustable to me either.6.2V is what I will check for.RACE ON!!!
Safety Car
Joined: Sep 2000
Posts: 3,524
Likes: 4
From: Hinckley Ohio
From my 96 manual....
TP sensor has a 5.0 volt reference, a ground and signal circuit.
TP sensor signal should be about 0.6 volt at idle. The TP sensor voltage should increase to above 4.0 volts at WOT.
P0123 will set if sensor voltage is greater than 4.8 volts.
P0122 will set if sensor voltage is less than 0.2 volts.
TP sensor has a 5.0 volt reference, a ground and signal circuit.
TP sensor signal should be about 0.6 volt at idle. The TP sensor voltage should increase to above 4.0 volts at WOT.
P0123 will set if sensor voltage is greater than 4.8 volts.
P0122 will set if sensor voltage is less than 0.2 volts.
Last edited by LT4BUD; Jul 12, 2005 at 01:09 PM.
Le Mans Master
Joined: Dec 2004
Posts: 5,789
Likes: 8
From: Myrtle Beach SC
St. Jude Donor '05-'06
Originally Posted by CFI-EFI
That is .62, not 6.2. You are going to have a problem getting 6+ volts from a 5 volt source. On the non adjustable TPS's, checking for idle and WOT is almost pointless except on a reinstall. What would be worthwhile, would be to check for a smooth progression all the way from idle to WOT, to check for any bad spots in the rheostat.
RACE ON!!!
RACE ON!!!
. That is what I did CFI I noticed a spot on my old one that caused a little hesitation around 1500rpm.With the new one it seems to work right through it now.
Le Mans Master
Joined: Feb 2002
Posts: 7,858
Likes: 2
The OEM TPS on all '92 - '96's is not the slotted adjustible type. The mount holes are round and allow for no slack around the mount bolts, hence no movement when mounted to the throttle body. PCM on these years will interpret signal as low as 3.7 volts as 100% TPS.
The question I have always had is where in the PCM is the reference comparator for WOT stored? I've gone over the BIN file (using Tunercat) of my '95's PCM image and never saw any value stored in the constants table designated as reference value for 100% TPS voltage. Seems it would have to be in there somewhere.
If the PCM automatically zeroes the TPS at idle voltage, then there has to be a hard coded upper limit value, i.e., a reference voltage value or comparator for the upper limit in order for the PCM to have a voltage range to use as reference for TPS resolution (throttle resolution). For instance, if the PCM interprets any signal above 3.7v as 100% TPS, and the TPS at idle produces .53v, then the effective operating range for the TPS (throttle resolution) is .53v to 3.7v (0% to 100%).
The question I have always had is where in the PCM is the reference comparator for WOT stored? I've gone over the BIN file (using Tunercat) of my '95's PCM image and never saw any value stored in the constants table designated as reference value for 100% TPS voltage. Seems it would have to be in there somewhere.
If the PCM automatically zeroes the TPS at idle voltage, then there has to be a hard coded upper limit value, i.e., a reference voltage value or comparator for the upper limit in order for the PCM to have a voltage range to use as reference for TPS resolution (throttle resolution). For instance, if the PCM interprets any signal above 3.7v as 100% TPS, and the TPS at idle produces .53v, then the effective operating range for the TPS (throttle resolution) is .53v to 3.7v (0% to 100%).
