1G TPS Sensor During WOT??

[Sinclair159]

quick question.. what % should my throttle position sensor be at at WOT??? off the top of my head i would guess 100% correct??? mine olny seems to hit 75% give or take a couple.... is that bad???

 

[Burnett03]

quick question.. what % should my throttle position sensor be at at WOT??? off the top of my head i would guess 100% correct??? mine olny seems to hit 75% give or take a couple.... is that bad???

TPS should read 100% or close to 5volts during WOT. When not touching the pedal it should read 10% on the logger and about .45volts. Make sure yours is adjusted right and your cable is allowing the TB to open fully.

 

[steve]

Only adjust the TPS for it's correct idle voltage.

If the throttle physically opens 100% then what the TPS reads is what it reads. Do not adjust the TPS based on WOT voltage.
If the throttle doesn't open 100% fix the linkage.
If you have cruise control, remember there are other cables involved.

Steve

 

[spyderturbo007]

When not touching the pedal it should read 10% on the logger and about .45volts.

Is this specific to 1g's? My 2g always reads 0% without touching the pedal. It reads 98% at WOT so I'm really not worried about it, but just curious.

 

[steve]

Is this specific to 1g's?

Yes. 1G dataloggers report actual percentages, 2G's seem to scale the output.

I didn't notice Burnett03 specifying 0.45v before. The correct value for a 1G TPS at idle is 0.48v to 0.52v. I set them to 0.5v, which is 10% of the possible max of 5.0v

On a 2G you don't adjust the TPS based on it's output, you adjust it based on where the the internal IPS opens.

Steve

 

[Sinclair159]

how exactly would i determine that my tb is open 100% at WOT??? would i just remove the uicp and look ???

 

[steve]

Would i just remove the uicp and look ???

Yep, have somebody mash the gas pedal and check. Turning the pulley at the TB isn't going to tell you if you have a cable issue. It may open 100% by hand but never using the pedal.

Steve

 

[Turbo Talon DL]

Im doing a search right now for 'throttle position sensor' and stumbled onto this thread. I have all kinds of TPS issues. I have a CEL for the TPS, and my TMO says my throttle position %age is all over the place, up, down, and if it could go left and right, im sure it would ! But anyhow, on or off the throttle, the readings dont change. I have checked resistance of the TPS and its well within spec, nice, smooth resistance changes. I need a schematic of where the TPS wires and such run because Im convinced that its a wiring issue, seeing as my TPS itself is good. I checked the pins on the TPS connector, and only one of them was reading 5v from the pin to ground. I checked the ecu side from the TPS connector, but only one of the three read into the designated TPS pin on the ecu side. The other two; one read into vehicle speed sensor, and the other read into something else, dont exactly remember. I got continunity, but improper voltages and I dont know where all these wires run, so I cant repair them. If anybody knows where I can obtain a wiring schematic of the TPS circuit, hook me up.....

 

[Turbo Talon DL]

Im dying here I cant find a TPS wiring diagram anywhere. My Haynes doesnt have one, and I cant find one doing a google on the net. Somebody has GOT to have one somewhere.

 

[steve]

Stop crying.
This should cover you over until you have bought the Manual CD

http://simon.chi.il.us/~steve/Auto/DSM/ECUwiring.gif

Steve

 

[Turbo Talon DL]

---->>>> ---->>>> Thanks. Im going to make good use of this. Can somebody say 'reputation points'? Now, would any other sensors/systems in the car such as the vehicle speed sensor (reed switch) cause a TPS code to be thrown? I had a CEL one time for a vehicle speed sensor, but it only flashed and went back off. I cleared that code out and it never showed up again. The only reason I ask this is because on my 4g37 when I left my coolant temp sensor dis-connected, I was throwing MAS, barometric press., and IAT codes. WTF

 

[steve]

As far as I know, the TPS CEL is only caused by a malfunction of the TPS or IPS and their respective harnesses. When you get other codes along with the TPS you need to check the ECU sensor ground and sensor power circuits and make sure they are not blown or damaged.

Steve

 

[Turbo Talon DL]

IPS? Idle position sensor? I never heard that acronym. Im gonna re-wire my TPS circuit anyhow, my TMO says its spiking all over the place. According to that wiring diagram you posted for me (thanks BTW) the TPS circuit ties into the MAS. I was reading wires as well and for whatever reason, it reads into the vehicle speed sensor. Either way, im gonna read wires and do a re-wire tonight!! I'll post results and updates as well as to help you assist me in troubleshooting.

 

[LaN-]

dont forget to take out your floor mat and see what happens, yes it sounds stupid but i've seen it be the problem

 

[steve]

IPS? Idle position sensor? I never heard that acronym. Im gonna re-wire my TPS circuit anyhow, my TMO says its spiking all over the place. According to that wiring diagram you posted for me (thanks BTW) the TPS circuit ties into the MAS. I was reading wires as well and for whatever reason, it reads into the vehicle speed sensor.

The IPS is the switch on the back of the throttle body that tells the ECU the throttle is closed. The signal from the ECU is grounded by the IPS when the throttle is closed and floats as soon as it starts opening.

The VSS (vehicle speed sensor) in on pin 18 the TPS is on pin 19 and the sensor ground for the TPS (and MAF/ECT/EGR) is on 17 and 24. The TPS and MAF also share the +5v sensor power from pin 23. Make sure the wires for 18 and 19 aren't shorted or that your looking at the right pins. Normally there isn't any interaction between the TPS and VSS.

Steve

 

[Turbo Talon DL]

Ok, to my EXTREME dismay...
I have about 6 pairs (yes six) of wires that read together:4&5, 11&12, 13&14, 18&19, 20&21, 23&24

All these wires read to chassis ground: 3,4,5,7,10,11,12,13,14,18,21,23,24 I just read them all to ground, just out of cureosity. Im pretty sure almost NONE of these should read to ground. I have lots of re-wiring to do. All I was planning on doing was splicing right from the ecu connector, around the bad section, and then into the engine bay to the affected component. It should take me quite a while. Guess when my wiring harness was -transplanted- it was chafed to the chassis somewhere. Thats whats been going on I really do feel sick thinking about this, im not getting much sleep this week.

ignore this post, its inaccurate

 

[steve]

Make sure when your measuring things that you use the lowest resistance scale on your multimeter and note that you can and will see resistances between points that you may not expect. Only those that read 0 ohms are direct paths. Even long wire runs should read more than a few tenths of an ohm from one end to another. There are various ways for some of the wires you check to have current paths to ground. You'll get different readings with the ECU plugged in vs not as well.

Steve

 

[Turbo Talon DL]

I got it figured out now. I mis-read a couple things, me being the tired soul that I am I got it now, Im gonna finish up wiring tomorrow after work and then rip apart my timing belt cover for an oil leak, and drop the pan to remove the pump/front case.

 

[Turbo Talon DL]

Update: I read for power and it all checked out. I read from power to ground, and power to chassis ground. It was good. Didnt get anything from the signal wire to ground tho I had it adjusted for a moment so that it didnt do roller coasters on my TMO, but it wasnt registering at all... I re-adjusted it and it still roller coasters with no reguard to throttle position.

Second Update: I just jumpered around the stock harness and ran a wire from the ecu pin 19 to the tps signal wire under the hood, still wacky roller coaster TPS readings I even took the signal wire out of the picture, and still same bad readings, 86%, 13%, its random. There has GOT to be something else that affects TPS readings. You know, like on the 4g37 when the coolant temp sensor (ecu) isnt plugged in, it will cause all 3 MAS codes, somethings gotta be causing this TPS reading to be bad. The wires are good, power and ground read steady, no intermittent opens or shorts. If anybody else would care to help bail me out so I can have a car for college, I'd greatly appreciate it. If anybody lives near Quincy IL, that could be an even bigger plu$.

 

[Turbo Talon DL]

I checked the idle switch on the throttle body for voltage, it reads just over one volt. I just wanted to make sure it was actually closing how it should. I put a volt meter inline with the switch and the connector. I still would like some help if there's any to be offered, I've tried everything I can think of aside from another ECU, which is out of the question.

 

[steve]

You should see 12v at the connector when the throttle is open and close to nothing when it's closed, with the green wire attached. Usually I disconnect the wire and just measure resistance between the connector and ground. I should be zero ohms closed and infinite open.

There is a grounding strap on the throttle body to make sure the IPS works.

Steve

 

[Turbo Talon DL]

So, you're saying that all I need is a ground wire from the t-body to the firewall? I dont have one on the T-body, but have one on the intake mani throttle cable bracket. I'll try that one out tomorrow or whenever I can get this oil leak situated....man...im dying.... too many gripes, not enough brains or me's to fix them...

 

[steve]

I'm not saying anything, just giving you information about what should go on normally.

The ground strap for the TB runs from one if the TB bolts to a screw on the top of the TB.
On '90's if on the top rear bolt and on later cars the top front bolt. It there to make sure that the IPS actually grounds the signal from the ECU on the IPS green wire when the throttle closes.

Like I said earlier, if the IPS wiring is good you will see battery voltage on the green wire when it's disconnected, close to zero volts then it's connected and the throttle is closed and battery voltage when the throttle is open.

A lot of the ECU signals work like this. The power is applied to the wire using a resistor that limits the current. These are called pull-ups and the ECU senses if the voltage on the wire is the pull-up voltage or zero because it grounded.

The TPS uses a different method. There is a variable resistor in the TPS. One side is grounded and the other is at 5v. As the TPS turns a wiper moves across that resistor and picks up a voltage between 0 and 5v depending on if it's closer to the ground end or the 5v end. From what I've seen the TPS usually fails from the wear of the wiper moving across the resistor when it gets hot.

If your seeing the TPS voltage as read by the logger swing with the TPS disconnected you might have an ECU problem. You can verify it isn't a short my disconnected the wire at the ECU harness. There is an article in the tech section on how to remove the wire from the connector without harming them.

Steve