87 gn tps issues

[sean lawrence]

I have a question for you that no one can seem to answer or can even attempt to answer and I am just at a stand still because I know the local mechanics will have no idea and will waste my time. I do all of my work and always have and have owned a mechanics shop for over 15 years. my question is I have went through 3 tps sensors all aftermarket and all of them will only go to around 3 volts when there supposed to go to 4.6 volts set correctly at wot but should be capable of 4.9 volts or so. why is it only going to 3 volts at wot? also that's just turning the arm on the tps to wot with the tps off the throttlebody eliminating the throttle cable, detent cable, cruise control cable and carpet issues that usually prevent the tps from going to wot. I finally got the correct tps sensor and that was hard to find gm part# 19187340 and I installed it and guess what it will still will not go above 3 volts at wot off or on the throttlebody. I then went to the wiring diagram and traced the tps wires back to the ecm. the grey wire is the 5 volt reference and its putting out 5 volts which is correct and it does not drop off voltage with tps plugged in or not and it stays 5 volts no matter what the tps arm is turned to, and that's what its supposed to do. ok on to the blue wire the return signal for the tps, just for the sake of the wire could be shorted out in the harness I unpinned the blue wire from the ecm which also eliminates back voltage if something is messed up with my ecm which I doubt, but I might as well check since I have done everything so I tested the blue wire from the tps at the ecm wherei unpinned it from the ecm and I still had the 3 volts at wot. next I unplugged the tps and looped the grey wire at the tps plug to the blue wire so I can make sure that wire was not shorted and I had a the full 5 volts like I should at wot. last I checked continuity for the black ground wire and it gave me a beep but kind of a high reading so I thought maybe a shorted ground wire in the harness so I back probed the ground and hooked it straight to the neg battery side to eliminate a bad ground wire. hooked it all back up and tested and still only 3 volts at wot. I really thought the aftermarket tps sensor was the problem but after 3 aftermarket tps showing the same and one factory tps straight out of the box from gm showing the same how could it be the tps? if all the wiring is good what else is there do check? I don't understand how if you have 5 volts reference why it will not let the 5 volts pass through the tps and to the return wire from the tps? because the tps regulates the voltage through the tps arm and its position soyou would think bad tps but with four tps sensors all saying the same how could it be the tps? I am really confused on this one has anyone ever had this problem? and what should I do next? thanks, sean

 

[whitehot1]

When installing the tps sensor with the key on and engine off and the 2 bolts loose are you pulling it all the way forward and rotating it upward to set it at .42?

So how do we adjust TPS voltage?
Turn the key to "Run" but, do NOT start the engine. Loosen the two bolts that hold the TPS in place enough that the TPS can be moved. Note that the TPS is slotted so that the sensor may be rotated as well as moved fore and aft. (The top slot affects the idle setting and the the lower slot affects the wide open throttle voltage) Push the entire sensor as far forward as possible so that the two bolts are up against the back ends of the slots. Then, rotate the top of the sensor CCW a bit until your scan tool indicates an idle TPS voltage of say 0.38-0.44 volts and tighten the retaining bolts so that the sensor cannot move. Note that the idle may change as you move the sensor. Don't be deceived that you have changed or improved the idle. When you shut the engine off and restart, the idle will go back to where it was before you moved the sensor unless the sensor was out of range to begin with. As stated prior, the ecm re-zeros the idle at each start.

Here is a link to a very helpful website that may help you in some way.

www.vortexbuicks-etc.com

 

[whitehot1]

Do you have a scanmaster and if so can you post all of the settings so that we can see if something might be out of adjustment that you may have not seen.

 

[sean lawrence]

When installing the tps sensor with the key on and engine off and the 2 bolts loose are you pulling it all the way forward and rotating it upward to set it at .42?

So how do we adjust TPS voltage?
Turn the key to "Run" but, do NOT start the engine. Loosen the two bolts that hold the TPS in place enough that the TPS can be moved. Note that the TPS is slotted so that the sensor may be rotated as well as moved fore and aft. (The top slot affects the idle setting and the the lower slot affects the wide open throttle voltage) Push the entire sensor as far forward as possible so that the two bolts are up against the back ends of the slots. Then, rotate the top of the sensor CCW a bit until your scan tool indicates an idle TPS voltage of say 0.38-0.44 volts and tighten the retaining bolts so that the sensor cannot move. Note that the idle may change as you move the sensor. Don't be deceived that you have changed or improved the idle. When you shut the engine off and restart, the idle will go back to where it was before you moved the sensor unless the sensor was out of range to begin with. As stated prior, the ecm re-zeros the idle at each start.

Here is a link to a very helpful website that may help you in some way.

www.vortexbuicks-etc.com

thanks for the help but I already know all of that this problem is way, way, way beyond that. I wish it was that easy and it should be but there is something else going on here. even kirbin performance does not have a clue and wants me to call him when I figure it out because he has never seen this problem and wants to know for customers in the future that have this problem.

 

[sean lawrence]

Do you have a scanmaster and if so can you post all of the settings so that we can see if something might be out of adjustment that you may have not seen.

no scanmaster but this is just the basics of electricity how this stuff works its very easy for me but this does not even addup how its working

 

[whitehot1]

What made you decide to replace the tps in the first place, were you having engine problems? just curious as to what happened at the beginning to lead you to the tps.

How does the car drive when you go wot? or have you not driven it.

What are you using to set the tps?

No scan tool at all?

 

[Nick Micale]

Makes no sense to post this in 2 forums?

http://www.turbobuick.com/forums/threads/87-gn-tps-issues.400486/#post-3266688

 

[sean lawrence]

What made you decide to replace the tps in the first place, were you having engine problems? just curious as to what happened at the beginning to lead you to the tps.

How does the car drive when you go wot? or have you not driven it.

What are you using to set the tps?

No scan tool at all?

I did the 87 conversion on my 84 gn and replaced everything new so after I built the motor all forged and arp studded and h beam rods and cam I cranked it up and it idled high and ran like crap, unplugged tps and idle was good but still higher than 450 rpm but ran good until half throttle then bogs out but that was a separate problem I was dropping fuel pressure under boost so a new high flow fuel pump will fix that problem. so that's when I used a voltmeter and set the tps at .42 volts at idle but it will not go up to 4.60 volts only a max of almost 3 volts. and that's when the problems began. but if I leave the tps unplugged its drivable no problem. so the ecm is kicking it into open loop mode when I unplug the tps and its fine so that tells me my ecm is working correctly so something else is going on here.

 

[sean lawrence]

Makes no sense to post this in 2 forums?

http://www.turbobuick.com/forums/threads/87-gn-tps-issues.400486/#post-3266688

just to get more views from people who just look at certain forums I figure the more people who see it the better because no one has a answer at all

 

[sean lawrence]

Do you have a scanmaster and if so can you post all of the settings so that we can see if something might be out of adjustment that you may have not seen.

another way for you to understand this problem if you take your tps off the throttlebody and plug it in and turn the key to run you can hold the tps in your hand and move the tps lever with you hand, so with out pressing the lever down it should be 0 or .01 basically 0 and if you press the lever all the way down on the tps it should be 4.9 volts maybe even 5.0 volts because the sensor only has 5 reference volts to work with. with my tps lever pushed all the way down its only 2.8 or so and sometimes 3.0 volts max and far cry from 4.6 volts at wot. so no need to set the tps when all four tps sensors read the same and with the tps being off the throttlebody you can push the tps lever down farther than you could with it being installed on the throttlebody so it should hit 4.6 volts off the throttlebody no problem because there are no restrictions what so ever. any ideas of how I could talkto about this?

 

[whitehot1]

You do have a strange issue there. Maybe you could contact John at Caspers Electronics if anyone could help it would be him,an electrical guru.

I was curious so i went out and checked.
I plugged my spare tps in and it read 00 just connected and rotating the lever all the way it read 4.74 on the scanmaster.

I reconnected my tps on the car and it reads .42 key on engine off and 4.64 wot

 

[sean lawrence]

I think I have found the problem does anyone have the wiring diagram for the aldl connector I don't need that I need the plug beside it there kind of a double plug you know. I have three wires not hooked up because mine is a 84 with a 87 transplant and I think this is causing my problem. it really needs a 87 dash harness but with only the or four wires to connect I will just wire them in myself I just need the 87 wiring diagrams to show what they are and where they go and I think this will fix it. I have looked at many diagrams but they only shows the aldl connector and how its wired. how would have the other wiring diagrams on here?

 

[sean lawrence]

You do have a strange issue there. Maybe you could contact John at Caspers Electronics if anyone could help it would be him,an electrical guru.

I was curious so i went out and checked.
I plugged my spare tps in and it read 00 just connected and rotating the lever all the way it read 4.74 on the scanmaster.

I reconnected my tps on the car and it reads .42 key on engine off and 4.64 wot

yea your numbers are dead on I wish mine was....LOL....

 

[davelostmissing]

http://www.vortexbuicks-etc.com/ecmwiring.htm

 

[davelostmissing]

I think I have found the problem does anyone have the wiring diagram for the aldl connector I don't need that I need the plug beside it there kind of a double plug you know. I have three wires not hooked up because mine is a 84 with a 87 transplant and I think this is causing my problem. it really needs a 87 dash harness but with only the or four wires to connect I will just wire them in myself I just need the 87 wiring diagrams to show what they are and where they go and I think this will fix it. I have looked at many diagrams but they only shows the aldl connector and how its wired. how would have the other wiring diagrams on here?

Sounds like you have something else in parallel with the TPS wiper(signal) wire

 

[sean lawrence]

the diagrams did not show what im looking for only the aldl under the dash and its pinouts. that's all correct. I need the diagram for the connectors behind the glovebox coming off the ecm wiring harness. you have the two plugs that go to the ecm then you have to more smaller connectors that are made together one side goes straight to the aldl and that's good but the other one beside it is what I need the diagram for because that's the wires that are cut or missing because its the 84 gn inside wiring harness. so please any help with that would be awesome maybe its in with the alarm diagram because its right beside it. I cant find that diagram because I guess people don't want others figuring out how to bypass our alarm or something. please someone send me that diagram or the correct one anyway if you know what im talking about.

 

[davelostmissing]

I don't think it will be presented in the way you are looking for, you will likely need to follow each signal thru the splice points and connectors.
I would be tempted to run new wires ECM-TPS directly.


-----from---- http://www.turbobuick.com/forums/threads/service-manual.395266 ----------------

https://kat.ph/trsrvman-iso-t7395056.html
quote
-- You'll need a BitTorrent client to download the iso. I have always used uTorrent myself. Please consider seeding for a while after you have the iso downloaded to we can help it spread quickly.

people who have issues with ISO format :
I've uploaded a torrent with the files already extracted for immediate use. It can be found here:
http://kat.ph/trsrvman-t7397823.html

https://www.box.com/s/blaqci2vl8niwlzwq6k9

That's the direct download for the ISO.. See if it works folks
..


I uploaded it to google drive

https://docs.google.com/file/d/0B_taSEdSERBnSzlWSkZtTWJhbjA/edit?usp=sharing

Anyone with that link can download it directly from google without needing a torrent, should be valid forever

 

[KEVINS]

FYI, there are JUNK TPS sensors out there that just are NOT capable of going that high. I went through the same problems last year with two brand new ones before the third one finally gave me the voltage needed.

ks

 

[davelostmissing]

Disconnecting the signal wire AT THE TPS and measuring AT THE TPS while actuating it fully would prove that. Hard to follow that first paragraph but I think he only tested at the ECM so could have other issues.

 

[mikestertwo]

You mentioned you ran the ground wire for the tps sensor to the battery. That is a mistake. The tps ground wire has to go back to the computer not the battery. The tps shares it's ground with the coolant sensor and the air temperature sensor. Try unplugging the coolant sensor and the ATS and see if you still have the problem. Maybe I missed it but how are you measuring the voltage and with what? On a side note you don't need 4.6v@WOT. Anything over 4.1 volts is enough.