adjust your TPS (another free hp mod)

[gijoecam]

i think all that information actaully supports the TPS mod. if your moving you lowest voltage reading to .96, then its definatly going to start learning .96v compared to .95v. Since this mod is really not about performance but "how far you physically have to push the gas petal"

JamesT initiated it so you dont actually have to push the gas petal as far down as you usually do to get the same effect.

I would tend to agree with that argument if I hadn't stumbled upon this earlier this morning (accent added):

Throttle Position Sensor
The throttle position (TP) sensor (Figure 42) is a rotary potentiometer that provides a signal to the PCM that is linearly proportional to the throttle plate/shaft position. The sensor housing has a three-blade electrical connector that may be gold plated. The gold plating increases corrosion resistance on terminals and increases connector durability. The TP sensor is mounted on the throttle body. As the TP sensor is rotated by the throttle shaft, four operating conditions are determined by the PCM from the TP. Those conditions are closed throttle (includes idle or deceleration), part throttle (includes cruise or moderate acceleration), wide open throttle (includes maximum acceleration or de-choke on crank), and throttle angle rate.

From what I gather from the info in the Powertrain Control information, the actual voltage that the TPS outputs is irrelevent. It sees the lowest voltage after startup and sets that as closed throttle/idle. Then if you crack the throttle (i.e. raise the output) it sees part throttle. If the voltage gets above 4, it sees WOT. The PCM also measures the rate of change so it can determine if you're just gently accelerating, or if you are calling for a transmission kick-down to pass.

Maybe I'm mis-interpreting the info in the service manual?

From a design standpoint, the ratch voltage adjustment compensates for the slight variations everyone experiences right from the start from vehicle to vehicle. Different installation methods, slight differences from one TPS to another or one brand to another should be compensated for by the PCM by the way it interprets the signal.

I dunno.....

-Joe

 

[Funmobile]

Brett F.,
I would definitely clean the throttle body and I would check the curb idle before I would start adjusting the TPS. Here is a link on how to do that Idle Adjust .

Gijoecam,
That is correct, it relearns the lowest throttle setting every time you crank the engine. So you might as well start off with the setting at .96v or .98v(my fav).

 

[vervepipes]

i did the TPS test, my ex passed fine, but my friend's cherokee was way off, i adjusted it and he can't believe the huge differance in fuel economy, in fact he was so impressed he payed me bonus!

 

[gijoecam]

Gijoecam,
That is correct, it relearns the lowest throttle setting every time you crank the engine. So you might as well start off with the setting at .96v or .98v(my fav).

So what's the difference if it starts at .96 or .63 or 1.9? If it learns that as the ratch, and the response to throttle position is linear, what's it matter where it starts? I've got my doubts as to whether it really CAN make a difference because of how the PCM is programmed to interpret the signals.

 

[tomballpkr]

I had a heck of a time getting the phillips screws out of the TPS on my 2000 Explorer Eddie Bauer V8. The TPS is mounted on the side of the block and I had to remove the cruise control module and antifreeze reservoir. Had to use a dremel to put a slot in the bottow screw to take it out because I stripped it trying to get it out since there wasn't a way to get much leverage.

Anyway, mine was 0.80V when I started and now it is 0.96.

I took the advice of a previous poster and purchased two replacement screws that allow the use of an Allen wrench to install/remove. They were $0.80 at Sears hardware. This allowed me to install/remove the screws without needing to remove anything and no stripping of screws.

We'll see if this improves anything.

 

[Dash Riprock]

Brett F.,
I would definitely clean the throttle body and I would check the curb idle before I would start adjusting the TPS. Here is a link on how to do that Idle Adjust .

Gijoecam,
That is correct, it relearns the lowest throttle setting every time you crank the engine. So you might as well start off with the setting at .96v or .98v(my fav).

Is this the same procedure as on a 95 XLT or other models? And in previous posts Ive seen mention of disconnecting the IAC, is this the same as the ISC as depicted inthe link above?

Thanks

 

[gijoecam]

Just looked at that link... I don't see the point. Re-setting the closed position on the throttle plate will simply re-establish the ratch voltage as the lowest setting, and the IAC will open or close accordingly to compensate. You do not teach the engine a new idle speed that way. In setting it the way the procedure says to, you simply use the throttle butterfly to regulate the idle instead of letting the IAC (i.e. the computer) do it.

I would call that a band-aid fix by a back-yard tinkerer. The real problem that is causing the fluctuating idle in that case is the IAC not opening/closing properly. This is just a band-aid fix that doesn't fix the problem.

I see it causing some other potential problems too: Set it using that procedure in the desert on a hot, dry day. Then take that same vehicle into the mid-west in the wintertime, when it's cold and damp, and you'll see a high idle due to the increased density (i.e. mass) of the incoming air, and it'll likely throw a code for the IAC not working properly since the IAC can't close any further to bring the idle back down.

Sorry for the tangent... as for your question, the IAC looks the same, but may be in a slightly different spot on your engine. It'll be mounted to the throttle body.

-Joe

 

[Bills98Explorer]

Ok I had to try this,starting volts.989,adjustment without drilling .96
Idle is smoother.Didn't run it down the road yet but so far so good.Now off to look for the throttle cable adjustment.

 

[yosh18981898]

Well, I just did the mod on my 92.

My TPS had those metal sleeves everyone was complaining about. I pushed them out, drilled out the plastic, and pushed them back in. Mine was 0.7 when I started (my digital meter only does 1/10 decimals) after adjustment, it is 0.9.

It only made a slight difference in idle quality. There is definately a noticable difference in throttle response though. The most noticable difference was when I was going 60 mph in 5th gear (manual trans) and I dropped into 3rd and mashed the gas. My x took off like a bat out of hell, the next time I looked at the speedometer, which was no more than 2 seconds later, I was doing 78! Even at the 3rd-4th shift at 90 mph (stupid 3.27 gears ) It was still accelerating hard enough to plant me in the seat.

That aint bad for a 4.0 OHV!!!

 

[kdogg212001]

has anyone done this for a 94 4.0?? if not then maybe i will accomplish this today! with pictures and all. wish me luck!

 

[410Fortune]

OH man here we go.
Yes it has been done on a 94, many many many times and covered in this thread extensively.
This is like a 5 minute proceedure, we dont need pics, they are already here.

Good luck!

 

[kdogg212001]

as you might notice 410 this post was freaking huge! much easier for my eyes if i just asked!! didn't know you would be the one here to respond! lol any who i will return later with my results! later dude!

 

[410Fortune]

Its allright man I know you get excited about this stuff, lots of us do too, but sometimes its better to slow down and read. It takes alot of people alot of effort to try and respond to every thread on this forum, adding to threads with the same questions that have already been answered just means more BS to read through

 

[Rhett]

as you might notice 410 this post was freaking huge! much easier for my eyes if i just asked!! didn't know you would be the one here to respond! lol any who i will return later with my results! later dude!

410 makes a good point about not needing to add the same stuff to what's already in this thread...it's ALL here and I mean all...

FYI kdogg I have a 94 and I have done this procedure. Amazingly, it DOES make a difference in the throttle response. Keep in mind that on my 94, I did NOT have to do any dremmelling at all to acheive the spec voltage. Just a little movement of the TPS and that was it.

 

[kdogg212001]

ok rhett i am going to do this today so as soon as you can respond to this the better for me! your saying that you didn't have to do any drilling to get yours match up to .96 volts? just a little jiggle?

 

[410Fortune]

thats pretty common, its not a jiggle, there is a tiny bit of play in the TPS screws already.

Be careful when you remove the TPS, note how it is installed, if you remove it.

the factroy setting wont be as far off as you think, in fact most I have seen have been right around the .96, .94 or so....

 

[Rhett]

ok rhett i am going to do this today so as soon as you can respond to this the better for me! your saying that you didn't have to do any drilling to get yours match up to .96 volts? just a little jiggle?

That's right, no drilling at all on my 1st gen. I don't know how the 2nd gen trucks are, maybe they require some more work...And yes the factory screws allow some play, so you can wiggle it around until you get .96. And the two 1st gens I've done this on, both were already very close anyway. When I installed the BBK TB on mine I wanted to make sure that I had the TPS pretty close to factory spec, so if I had any other problems I would know that the TPS was ok.

You will also want to calibrate the idle speed as per instructions that came with the TB (It's the same as what I posted above with the 500 rpm with IAC unplugged) or else you'll get weird idling behavior. I consider this far more important than messing with the TPS because the TPS's are usually pretty close on our trucks anyway.

 

[kdogg212001]

ok you lost me for a second! IAC isn't the TPS?? or is that the cable thats plugged into it?

 

[spindlecone]

ok you lost me for a second! IAC isn't the TPS?? or is that the cable thats plugged into it?

At this point, would suggest you not mess with the adjustment, you need to read the thread

 

[kdogg212001]

i just checked my 94 xlt and the wiring for the TPS that worked for my reading is the far right wire(that would be your positive) and using the far left wire as my negative. now i got 4 volts just like husky, so i turned my down just as much as the screws would allow and it only moved to 3.99volts in order to reach the .96i would have to twist the TPS all the way around. not to sure this is for 1st generations can anyone help explain a little