adjust your TPS (another free hp mod)

[Rogers-Explorer]

TPS 1997 Explorer

I have a 97 XLT 4.0L OHV. After struggling with the ridiculous screws holding the TPS on, I had a look at the wiring - no green wire. I have three wires - black/gray, black/red, gray.

I checked the voltage to each - -0.02V, -0.02V, -4,97V.

Am I missing something?

Cheers, Roger

 

[Gator Jeff]

I have a 97 XLT 4.0L OHV. After struggling with the ridiculous screws holding the TPS on, I had a look at the wiring - no green wire. I have three wires - black/gray, black/red, gray.

I checked the voltage to each - -0.02V, -0.02V, -4,97V.

Am I missing something?

When you checked the voltage, was the TPS firmly in place? Your comment about struggling with screws leads me it wasn't, perhaps removed even. You need to check the wires with the TPS in place. Your –4.97 reading is likely the right wire, only with the polarity reversed and again I’m thinking the TPS was removed since the sensor range as indicated earlier in the thread is in excess of +4V at WOT.

Try post #117 on pg 6 for the proper wires for your year. There maybe other color info further on, but I have to leave for a trip in 3 hours and really can’t search for it now. In any event, when you have the TPS back in place, there are only 6 combinations. 3 pairs actually (each pair being a positive and negative of the same number). Only one of those will be close to what you’re looking for. How close will determine how much you need to do this, but looking at what others saw, you can expect somewhere between about .79 and 1.01. I was at .91 originally and it made a significant difference.

Good luck.

 

[redsport96]

I checked my voltage reading and it was 1.02. Reset it to .963 but have yet to drive it. As far as getting the screws out, I used the reverse direction ratchet function on my 19.2 volt cordless drill. It worked pretty good. I slowly ajusted it to get stronger and kept trying to loosen it, eventually at the number 20 setting it spun out the screws.

 

[redsport96]

Drove the vehicle after the TPS adjustment and it has made a difference. It used to stumble at light throttle and would jerk when driving through town at 25 MPH. It now runs a lot smoother.

 

[Rogers-Explorer]

follow-up

Finally got the screws out (the philips heads were stripped). Prior to removing the TPS, checked the voltage and got 1.03. I have another 4.0 (blew it this spring) and checked the voltage on that TPS and got .96 (stripped screw heads on that one too). So, I just traded one for the other. I was lucky - as I didn't really feel good about drilling out the holes in the TPS, as I too have brass inserts that would have been difficult to drill out.

I've driven the truck for a few weeks and there is a small difference in response. I have been preoccupied with getting rid of my P0171/P0174 codes, so haven't paid much attention to the TPS, although my fuel mileage has greatly improved. BTW, I replaced the philips head screws with a few 5/16" bolts - works great for R&R.

Cheers, Roger

 

[Gator Jeff]

I have another 4.0 (blew it this spring) and checked the voltage on that TPS and got .96 (stripped screw heads on that one too). So, I just traded one for the other.

You may have not solved anything. Any functioning TPS will read .96 if in the proper orientation. What you saw was that the TPS on your blown motor was in the proper orientation to begin with. When you swapped them, it may not have gone back in, in that proper orientation. Check your voltage to be sure.

I was lucky - as I didn't really feel good about drilling out the holes in the TPS, as I too have brass inserts that would have been difficult to drill out.

It's actually quite easy. Use a bit just a bit bigger than the hole and it will likely bind with the insert, and you'll be able to rotate it out. Just use a low speed setting on your drill. That extra millimeter of diameter in the screw hole should be all you need to rotate the TPS to the proper orientation if it doesn' read .96 when you check the voltage.

 

[Rogers-Explorer]

You may have not solved anything. Any functioning TPS will read .96 if in the proper orientation. What you saw was that the TPS on your blown motor was in the proper orientation to begin with. When you swapped them, it may not have gone back in, in that proper orientation. Check your voltage to be sure.

Good point, though I am sure I checked the voltage after I installed the new TPS - I will go out and give it another check.

The truck idles around 14-1500rpm and when it warms up a bit I give a little shot of gas and it settles down to abou 7-800rpm, kind of like the automatic choke in my '77 mustang I use to have. Do you suppose the TPS has anything to do with this?

I believe I have a vacuum leak somewhere and will eventually replace all the lines, but since I changed the TPS the motor has settled down a little bit. When we put the new(er) engine in I also swapped some of the top end parts (fuel rail, plenum, IAC, FPS, etc...), but can't remember which throttle body I used. One of them I took the throttle plate out and cleaned it up - this may be the throttle body on the truck and may be the reason for the sticky idle. The only thing that tells me that this may not be the case is the idle settles down 'after' the motor warms up a bit.

hmmm, any ideas?

Thanks very much for your feedback Gator, I will follow your advice.

Cheers, Roger

 

[Fredness]

I love these threads...
To the nay-sayers: Just because it did nothing for you doesn't diminish its worth.

It worked for me on 2 of 3 vehicles, especially the Explorer.
As for reading the EEC tables, I wish it were that simple. The tables don't tell you the math behind the numbers, what the numbers are being used for and how the PCM reacts.

The TPS is used for SO much more than idle, it triggers the open loop flag (shut down the O2 sensors and run off commanded fuel), shuts off the AC (and Alternator on some!), determines shift points on auto's and more. THe TPS/PCM relationship is pretty special.

The factory puts a +/- on the values and there is some learning on functions, but if the sensor is old/worn, it may not be within spec. This is to get it there. If it has drop-outs or if it is noisy (meter bounces instead of a fluid movement), the TPS should be replaced, even if the high and low numbers are correct.

Example: data logging a cutomers Ranger and the stock settings NEVER went to open loop. The TPS was correct, it was reading 4+V @ WOT, but the PCM never went to open loop. Reflashed with a "custom" tune that was bone stock and it did the same thing. Dropped the openloop TPS from .650 to .500 and bingo! Open loop everytime and big performance gains.

Also, as with any other modification/adjustment, there is the assumption that EVERYTHING ELSE IS CORRECT. That's a pretty bold assumption...

 

[Hokie]

My Mounty reads 1.05V, I want/need to adjust it but I can't get the screws out to save my life. I even tried removing the throttle body but the gaskets were holding it pretty firm too

I have a right angle ratcheting screwdriver, I put a wrench on the back of it to help hold it and still couldn't get the friggin' things loose.

 

[badgett]

Did this to my 98 and love it. First reading was .55. Got it to .96. I also have a dodge neon with a TPS sensor that looks almost like ours. I wonder if this would work on a dodge?

 

[Rogers-Explorer]

Problems with the TPS Screws

Hokie: "...but I can't get the screws out to save my life. I even tried removing the throttle body but the gaskets were holding it pretty firm too...and still couldn't get the friggin' things loose."

Hokie, I had the exact same problem. I tried vise grips, ratchet screwdrivers, hammers, etc. I ended up grinding the heads off and slipping the TPS off and then it is easy to pull the screws out by getting a set of good vise grips on them. Just be careful when you grind, it may be easier with a dremel or something like that, I used a 4" grinder and had no problems. I then replace the screws with 2 bolts with real heads on them.

Hope this helps.

Cheers, Roger

 

[Pdwight]

Putting them back in

When you put in new screws use a bit of anti sieze compound on them, the problem is Bi-Metal adhesion, carbon steel screws in an aluminum part is why these become so stubborn.

Dwight

 

[muzzymaniac]

Did a little poking around on my 04. Seems there are 4 wired
Pink/Red
Grey/white
Yellow/white x2

Didn't have time to test them, not sure which ones to start with.

 

[Jeffbethandkidz]

Did a little poking around on my 04. Seems there are 4 wired
Pink/Red
Grey/white
Yellow/white x2

Didn't have time to test them, not sure which ones to start with.

That is because your truck is "drive by wire" and you may not have been checking the throttle body throttle position sensor, but the throttle body actuator motor wires. You actually have two sets of "throttle position" sensors. Well, maybe I am not saying that quite right. There is a "position" sensor on your throttle pedal, and another on the throttle body throttle blade. They are also "dual range" position sensors. They read two different scales to compare against eachother as an error check function. If one is not reading accuratly compared to the other, it will "default" and allow on idle to prevent uncommanded throttle input. For example, if one of the two ranges is inaccurate, and the system did not have an error check function, then the pcm could command a throttle position that the driver did not request. This could lead to an out of control situation. They started implementing this system when they went to "drive by wire" back in the early 90's. I believe it was first used on the Powerstroke Diesels when they went to DIT in '94 1/2.

That all being said, I don't think it will be possible to get the adjustment you are looking for. But I could be wrong about that. I guess you would need to determine which circuit is the low-to-high voltage run-up and adjust according to its reading. Then I assume you would have to do the same w/ the other position sensor to gain the maximum benefit. According to the EVTM, the GY/WH and the YE/WH are the two you would check on the throttle angle sensor, and the well.....hmmm. After examining the "accelerator pedal position sensor" circuits, and pulling my head out of my butt, I remember that the pedal sensor is all integrated into the pedal assembly and don't remember there being an exposed sensor. Maybe someone can correct me here.

I think that's all the damage I can do to this post.

Woops, I see that there are two YE/WH wires. One is the reference voltage circuit...it should have appx 5 volts. The other one is the one to check for adjustment.

 

[96XLTRanger]

Hmm. When i pull my IAC, it dies immediatly. This has to be performed. I checked the tps and got .96, but thats with the idle not being adjusted yet. I guess theoretically i'll have to set my TPS to .9 and then adjust the idle so that it turns the butterfly therefore raising the .9 to .96

 

[96XLTRanger]

Here's an idea. I'm sure you guys have bread ties sitting around that you can utilize.

Fold up the ends and stuff them in above the terminals on the plug. Easy testing!

 

[X-North]

I had 8.6 something like that ..i unbolted it and twisted ti by hand without drilling and it gave me 9.46 not the perfect but WOW what a difference

 

[Truth Explorer]

.96 not for me!

I just did the tps mod on my 2002 Limited. I have the 4.6 V8. It tested from the factory, @ .859. I moved it to .96 and the rpms shot up to 1200 from about 650. Adjusted it down to .90 and the idle slowed to 700 and the idle smoothed out. I noticed better throttle responce, Smoother idle, and a increse in mpg. Good free mod! Different for all vehicles I would say, but worth the tweak time without a doubt!

 

[X-North]

Man you should have the the earlier post theres a way to adjust the RPM.

 

[PRS]

Definitely worth the time and effort! Adjusted my 00 SOHC from 1.13v down to .960v and the throttle response is AMAZING.
I used a combination of an adjustment to the set screw on the throttle body and the TPS.
It idles perfectly smooth a hair over 500. Couldn't be happier.