Another TPS Adjustment Question
Thread Starter
Racer
Joined: Feb 2004
Posts: 445
Likes: 1
From: Atlanta GA
Another TPS Adjustment Question
Hello Fellas. Going to try to set the IAC and adjust the TPS tonite. I feel pretty confident about setting the IAC....seems simple. Now for the TPS.
1. Do I still have to ground out the A & B terminals to the ALDL before adjusting the TPS?
2. I'm going to try paper clips in the harness to gauge the voltage. Can I just place these in there when the car is turned off? Once I turn the ignition to the "ON" position I'm guessing I shouldn't touch the paper clips with my hands? Don't want to get ZAPPED!!
3. To actually adjust the voltage, I know that I have to loosen the two torx screws. Will simply loosening the screws "adjust the TPS" or will this simply allow me to move the entire plastic harness around until I find the voltage that I'm looking for (.065v)?
I've read through the tech articles but I guess I'm just trying to leave myself no room for error (either with the car, or myself....ZAP!!)
Thanks,
Jon
1. Do I still have to ground out the A & B terminals to the ALDL before adjusting the TPS?
2. I'm going to try paper clips in the harness to gauge the voltage. Can I just place these in there when the car is turned off? Once I turn the ignition to the "ON" position I'm guessing I shouldn't touch the paper clips with my hands? Don't want to get ZAPPED!!
3. To actually adjust the voltage, I know that I have to loosen the two torx screws. Will simply loosening the screws "adjust the TPS" or will this simply allow me to move the entire plastic harness around until I find the voltage that I'm looking for (.065v)?
I've read through the tech articles but I guess I'm just trying to leave myself no room for error (either with the car, or myself....ZAP!!)
Thanks,
Jon
Race Director
Joined: Sep 2000
Posts: 17,298
Likes: 33
From: The Top of Utah
Re: Another TPS Adjustment Question (Midnight89)
Once I turn the ignition to the "ON" position I'm guessing I shouldn't touch the paper clips with my hands? Don't want to get ZAPPED!!
Man electrocuted by 2 amps of 12 volt power!
1.) No.
2.) Nothing to worry about. You won't feel a thing. I exagerated. It isn't anywhere near 2 amps, and the spec is for less than 0.6 volts. If it makes you feel better, play it safe, but you are at no risk. Simply ignition on, engine off. Start by just barely loosening the TPS screws. It is better if it takes a little effort to move the sensor. That way it will move less when you snug it up.
3.) See above. Don't loosen the screws too much. You have to rotate the TPS in the slots provided, to adjust the volt reading.
It is a piece of cake. Once you've finished, you'll wonder why you asked. You have nothing to fear but fear, itself. Good luck, and...
RACE ON!!!
[Modified by CFI-EFI, 4:55 PM 3/19/2004]
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Another TPS Adjustment Question (Midnight89)
You need to jumper ALDL pins A&B and turn the ignition On for a minute of so to get the IAC pintel fully extended.
Then unplug the IAC connector, remove the ALDL jumpers, start the engine and set base idle to about 450RPM.
Shut the engine off, loosen the TPS screws slightly, probe the ground & signal wires with a DMM and rotate the TPS about the top screw till you get a reading of around .65Vdc (over .67Vdc may trigger a TPS code). Then open the throttle fully and tweak the TPS position for max WOT voltage. Recheck that the base idle voltage is still .65Vdc and tighten the two screws.
You can use a TPS diagnostic harness or simply jumper the pins in the connector to those in the harness.
Then unplug the IAC connector, remove the ALDL jumpers, start the engine and set base idle to about 450RPM.
Shut the engine off, loosen the TPS screws slightly, probe the ground & signal wires with a DMM and rotate the TPS about the top screw till you get a reading of around .65Vdc (over .67Vdc may trigger a TPS code). Then open the throttle fully and tweak the TPS position for max WOT voltage. Recheck that the base idle voltage is still .65Vdc and tighten the two screws.
You can use a TPS diagnostic harness or simply jumper the pins in the connector to those in the harness.
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Re: Another TPS Adjustment Question (65Z01)
65Z01
What about disconnecting the EST connector?
The tech tip left this out and the GM Shop Manual says to do it.
What is your take on this?
[Modified by 86PACER, 4:36 PM 3/19/2004]
What about disconnecting the EST connector?
The tech tip left this out and the GM Shop Manual says to do it.
What is your take on this?
[Modified by 86PACER, 4:36 PM 3/19/2004]
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
Re: Another TPS Adjustment Question (86PACER)
I have tried setting the base idle with and without disconnecting the timing connector. My 89 GM Helms manual says to disconnect it (bold print). The best result I have found is to do the adjustment with the connector disconnected. The tech article aslso did not say to adjust the timing before the base idle...but this should be done! My $.02 or whats its worth!
SAM
SAM
Team Owner
Joined: Dec 2000
Posts: 90,675
Likes: 304
From: SE NY
Cruise-In II Veteran
Re: Another TPS Adjustment Question (Sam Lam)
:iagree:
Though I didn't do the timing nor the EST, these are good ideas. However, I did adjust base timing after doing the TPS tweak.
Though I didn't do the timing nor the EST, these are good ideas. However, I did adjust base timing after doing the TPS tweak.
Thread Starter
Racer
Joined: Feb 2004
Posts: 445
Likes: 1
From: Atlanta GA
Re: Another TPS Adjustment Question (Sam Lam)
Thanks for the input guys. Where, exactly is the timing connector located? Is this a plug type wiring harness that I can simply "unplug" or it is more detailed than that.
CFI-EFI: thanks for the high voltage warning...J/K. I'm new to the whole "work on the car" thing, and you have now single-handedly eliminated my fear of getting ZAPPED!! Thanks, Jon
CFI-EFI: thanks for the high voltage warning...J/K. I'm new to the whole "work on the car" thing, and you have now single-handedly eliminated my fear of getting ZAPPED!! Thanks, Jon
Thread Starter
Racer
Joined: Feb 2004
Posts: 445
Likes: 1
From: Atlanta GA
Re: Another TPS Adjustment Question (Midnight89)
One more thing...
I'm getting ready to set the base idle. I understand that this is the small round hole at the top of the throttle body on the driver's side. Mine appears to be sealed with a thin piece of metal. Is it cool to pierce this with a screwdriver?
I'm getting ready to set the base idle. I understand that this is the small round hole at the top of the throttle body on the driver's side. Mine appears to be sealed with a thin piece of metal. Is it cool to pierce this with a screwdriver?
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Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Re: Another TPS Adjustment Question (Midnight89)
It is against the firewall near the wiper motor housing, between the left side valve cover and the brake booster. It is a snap type connetor. It should have a single tan wire with a black stripe.
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Re: Another TPS Adjustment Question (Midnight89)
One more thing...
Mine appears to be sealed with a thin piece of metal. Is it cool to pierce this with a screwdriver?
Mine appears to be sealed with a thin piece of metal. Is it cool to pierce this with a screwdriver?
Thread Starter
Racer
Joined: Feb 2004
Posts: 445
Likes: 1
From: Atlanta GA
Re: Another TPS Adjustment Question (86PACER)
86PACER....Thanks. Found it in about 10 seconds. At what point in the process of adjusting the TPS do I disconnect this plug? Do I do this before testing the voltage going to the TPS?
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Re: Another TPS Adjustment Question (Midnight89)
Disconnect it after you have jumped the "A" and "B" terminals with a paper clip, and after waiting at least 30 seconds (wait 1 full minute to be sure) for the IAC pintle to extend with the iginition switch to the "On" position. Then that is when you disconnect the EST, then the IAC connector. When you re-adjust the TPS only in the future, you do not need to disconnect the EST connector. Only when setting the timing and adjusting the IAC for minimum idle.
[Modified by 86PACER, 6:01 PM 3/19/2004]
[Modified by 86PACER, 11:50 PM 3/19/2004]
[Modified by 86PACER, 6:01 PM 3/19/2004]
[Modified by 86PACER, 11:50 PM 3/19/2004]
Thread Starter
Racer
Joined: Feb 2004
Posts: 445
Likes: 1
From: Atlanta GA
Re: Another TPS Adjustment Question (86PACER)
Thanks again 86PACER. Maybe some day I will be able to help someone through this.
The base idle is set...no problems. Here's what I did next and I'm running into problems:
With the key off, I inserted pins in the top (black) and middle (blue) wire on the TPS harness. Seem to have a good connection. Next, I turned the ignition on (engine off) and went to test the voltage at idle. I'm touching the positive lead (red) to the top wire and the negative lead (black) to the middle wire, but I cant get a consistent reading. The numbers are all negative and jump around wildly.
This is my first time with a digital voltmeter. Here's how I have it setup:
I'm turning my dial to 200m under the DCV setting. (I've also tried the 2000m DCV setting) The red tester is plugged into the 1000VDC / 200mA MAX plug and the Black tester is plugged into the COM 500V Max plug.
Anyone have suggestions as to what I could be doing wrong? Or is this a time where the "shouldn't have bought the $20 voltmeter" saying comes into play?
The base idle is set...no problems. Here's what I did next and I'm running into problems:
With the key off, I inserted pins in the top (black) and middle (blue) wire on the TPS harness. Seem to have a good connection. Next, I turned the ignition on (engine off) and went to test the voltage at idle. I'm touching the positive lead (red) to the top wire and the negative lead (black) to the middle wire, but I cant get a consistent reading. The numbers are all negative and jump around wildly.
This is my first time with a digital voltmeter. Here's how I have it setup:
I'm turning my dial to 200m under the DCV setting. (I've also tried the 2000m DCV setting) The red tester is plugged into the 1000VDC / 200mA MAX plug and the Black tester is plugged into the COM 500V Max plug.
Anyone have suggestions as to what I could be doing wrong? Or is this a time where the "shouldn't have bought the $20 voltmeter" saying comes into play?
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
Re: Another TPS Adjustment Question (Midnight89)
Midnight: Would you like to have a detailed procedure on doing the base idle? This is right out of the GM Helms manual. Let me know if you want it eamiled to you. It will answer a lot of questions for you.
SAM
SAM
Thread Starter
Racer
Joined: Feb 2004
Posts: 445
Likes: 1
From: Atlanta GA
Re: Another TPS Adjustment Question (Sam Lam)
Midnight: Would you like to have a detailed procedure on doing the base idle? SAM
My e-mail address: jbrinson7@aol.com
Thanks for everyone's assistance (and their patience) while I'm trying to learn.
Jon
Le Mans Master
Joined: Jan 2003
Posts: 5,858
Likes: 7
From: Santa Maria CA
Re: Another TPS Adjustment Question (Midnight89)
I set my Voltmeter to the 20K scale. Set it to where the decimal point is dirrectly to the left of the numbers you get at Closed Throttle. Example: .58 The reason why you see negative voltage is because you have the leads reversed. Flip flop the leads and you will see positive numbers. That really does not matter anyway. The reason why your Voltage reading is unstable is because you are not getting a good enough contact at the wires. I carefully stripped some of the wire insulation to expose the wires and get a better contact. Just to make sure, the harness must be connected to the TPS, and the key in the "ON" position to get a reading. Work on exposing some of the wire and get a little more contact on your Voltmeter leads. Once you do that, your reading will should stay steady.
And when it's all set and done, remember to disconnect your battery for about 5 minutes to clear that code 42 you threw when you unplugged the EST and started the engine.
[Modified by 86PACER, 3:38 PM 3/20/2004]
And when it's all set and done, remember to disconnect your battery for about 5 minutes to clear that code 42 you threw when you unplugged the EST and started the engine.
[Modified by 86PACER, 3:38 PM 3/20/2004]
Thread Starter
Racer
Joined: Feb 2004
Posts: 445
Likes: 1
From: Atlanta GA
Re: Another TPS Adjustment Question (86PACER)
Thanks for the tips 86PACER. Hopefully this will be the last question...
I have my voltmeter set at 20K and the TPS reading at idle displays "2.56" rather consistently.
Should I adjust my TPS until the gauge reads ".56", not "2.56"? Or is my current reading ideal?
I have my voltmeter set at 20K and the TPS reading at idle displays "2.56" rather consistently.
Should I adjust my TPS until the gauge reads ".56", not "2.56"? Or is my current reading ideal?
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
Re: Another TPS Adjustment Question (Midnight89)
Midnight: You should be measuring voltage on the TPS. Your adjustment of 20k would apply to reading OHMS. Just raising a question for you???
Thread Starter
Racer
Joined: Feb 2004
Posts: 445
Likes: 1
From: Atlanta GA
Re: Another TPS Adjustment Question (Sam Lam)
ahhhhh!! Thanks Bob. Now that makes a big difference. Changed gauge around and I have .65 at idle 4.65 at WOT (close enough!!).
Thanks for your help everyone. Right now I feel like a dog that JUST learned to roll over!!
Thanks for your help everyone. Right now I feel like a dog that JUST learned to roll over!!
Melting Slicks
Joined: Apr 2002
Posts: 2,118
Likes: 0
From: St. Charles, MO Route 66 Corvette Club
Re: Another TPS Adjustment Question (Midnight89)
Sometimes "little bitty" details make a big difference and welcome to being a Vette mechanic. You are fortunate to get your voltage reading at WOT. The best I can get at WOT is 4.2 volts with a .60 volts at idle. You may want to set your timing to 8 degrees before top dead center. A TPS setting of .65 and 8 degrees timing will make you Vette jump after the light turns green! Watch out for the man with the badge!!! :lol: :lol: :lol:
SAM
SAM