tps sensor
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The Shape
Founding Member
When I first got into stangs I bought into the whole deal about adjusting the TPS for performance. Until my original TPS died. It was raining and I had to be somewhere so I just swung by the parts store bought a TPS and a philips screwdriver and changed it in the parking lot. I have never touched it since that day and my car runs no different than it did before the original sensor went bad. I know they can and do go bad ,but I can't believe adjusting one to .99 volts instead of 1.3 volts are .97 volts makes any difference at all.
Michael Yount
Mustang Master
"but I can't believe adjusting one to .99 volts instead of 1.3 volts are .97 volts makes any difference at all."
You are correct - since at least 88, the computer looks to the tps voltage everytime the throttle closes, and resets the base voltage.
tiger - How big a hot cable did you run to the front of the car? Too small and you'll have starting and charging issues; it's needs to be much bigger than stock. You can ground the battery at the back of the car - just be certain it's a good ground with plenty of bare metal to metal contact. Ground the block to the chasis up front - again, good metal to metal contact. Wouldn't hurt to run a couple of 10 gauge grounds up from the neg. term of the battery to the computer and the tranny/engine - just to be sure.
You are correct - since at least 88, the computer looks to the tps voltage everytime the throttle closes, and resets the base voltage.
tiger - How big a hot cable did you run to the front of the car? Too small and you'll have starting and charging issues; it's needs to be much bigger than stock. You can ground the battery at the back of the car - just be certain it's a good ground with plenty of bare metal to metal contact. Ground the block to the chasis up front - again, good metal to metal contact. Wouldn't hurt to run a couple of 10 gauge grounds up from the neg. term of the battery to the computer and the tranny/engine - just to be sure.
Michael Yount
Mustang Master
"I tried grounding it..."
Were you not successful? I'm confused by your answer. The 12V+ was run to the front with the 1/0 welding cable? What size ground cable did you use in the back? Did you run anything from the neg. battery terminal to the front?
Were you not successful? I'm confused by your answer. The 12V+ was run to the front with the 1/0 welding cable? What size ground cable did you use in the back? Did you run anything from the neg. battery terminal to the front?
bryanrevans
New Member
So does the cpu on the 86and 87 make the same zero adjustment????Would a adjustment on any fuel injected 5.0 be warranted???????
Michael Yount
Mustang Master
bigtiger - Does it seem to be working ok?
Bryan - not sure what the ecu does on the 86 cars; the 85 HO's were carb'd; and I know idea how the CFI carb'd 85's (auto tranny cars) handle throttle position. Probst makes the comment in his Ford efi book that starting in 88....not sure what that means about 87's and 86's. I'd set it around .90V and leave it alone.
Bryan - not sure what the ecu does on the 86 cars; the 85 HO's were carb'd; and I know idea how the CFI carb'd 85's (auto tranny cars) handle throttle position. Probst makes the comment in his Ford efi book that starting in 88....not sure what that means about 87's and 86's. I'd set it around .90V and leave it alone.
bryanrevans
New Member
big_tiger15 said:
OK well I did a great test! I used a multimeter and a pair of jumper cablesI only used one end of the jumper cables and hooked it onto the postive terminal. Then hook the postive end of the multimeter to the jumper cable, and the negative to the front shock tower. wow only 4.6 volts!! SO I just got some old wire and ran a ground so it works (gets key hot). Now I just need to find out why it wont start.
Michael Yount
Mustang Master
although Michael and others have posted that the puter will adapt if it is within the puter's adaptive capability (im still not sold on that practically - on paper it might, but in practice i would rather dial it in. that makes one less thing for the puter to need to do).
.99 is stock setting but if your trying to get more out of your car advance it, that's what was told to me by a very reputable fellow mustanger, he has built 1,000+ RWHP Mustangs & been featured & interviewed in most all the mustang magazines & I have no reason not to beleive him.
He & his helper both started laughing when I said something about not moving it cause I already set it.
He & his helper both started laughing when I said something about not moving it cause I already set it.
the computer will zero the setting out (as long as it is not absurd). so your 1.2 volts will perform the same as if you set it at <1.0 V.Ray@VSK said:
with some things, more is better. this is part of the engine management, so that does not apply, IMHO. otherwise, we would all set our to 4.5 volts and the puter would think we are at WOT all the time.
if it runs fine, leave it (you seem set on it anyhow). but if problems arise in the future, i would keep it in mind.
TrickStang37
New Member
- Oct 17, 2004
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ive read that the computer only needs to read about 2.7v higher than the idle voltage to consider it WOT, so WOT would be about 3.7v or so, depending where it idles at.
computer resetting...
Im not buying it totally.... So when you turn the car on, is the computer assuming closed throttle? everything is set by comparison, so lets say you have your foot on the pedal, and the computer reads 2v when you turn the car on. will it assume 2v is closed throttle? so now lets assume that somehow the computer (without using TPS, because our foot has given it incorrect data) knows that the throttle is partially open. as you lift your foot, and close the throttle where it supposedy resets, how does it know where closed is? all it has to go by is that 2v is closed, and now youre throttle is way more closed.
the computer is designed to read within a range, and i wouldnt expect it to completely recalibrate the TPS each time you lift all the way off, because the tps is the only thing telling the computer you are in fact off the throttle completely.
just my $0.02 correct me, and punch me for using "$0.02"
Im not buying it totally.... So when you turn the car on, is the computer assuming closed throttle? everything is set by comparison, so lets say you have your foot on the pedal, and the computer reads 2v when you turn the car on. will it assume 2v is closed throttle? so now lets assume that somehow the computer (without using TPS, because our foot has given it incorrect data) knows that the throttle is partially open. as you lift your foot, and close the throttle where it supposedy resets, how does it know where closed is? all it has to go by is that 2v is closed, and now youre throttle is way more closed.
the computer is designed to read within a range, and i wouldnt expect it to completely recalibrate the TPS each time you lift all the way off, because the tps is the only thing telling the computer you are in fact off the throttle completely.
just my $0.02 correct me, and punch me for using "$0.02"
Michael Yount
Mustang Master
From Charles O Probst' "bible" - "Ford Fuel Injection & Electronic Engine Control", page 89, paragraph #7 titled (appropriately enough) THROTTLE POSITION SENSOR:
"Recent Ford systems, all EEC since 1988, use a Rotary TP. The potentiometer increases resistance as the throttle shaft rotates. It is not adjustable, but the control-module programming compensates for any difference in sensors, readjusting to a base voltage when the throttle is closed."
Included in the discussion of the TPS function is a graph showing degrees of rotation vs. voltage output of the TPS. It should be a linear ramp where voltage is directly proportional to degree of throttle opening, starting at .601V at 0 degrees of opening, and increasing linearly to 4.538V at 85 degrees of opening, with a +/- 3 % variation allowed.
Interpretation - changing the initial setting of the tps won't accomplish a thing. The computer re-establishes a baseline when the throttle is closed. Check the initial voltage between the black and green wires with the engine warm, key on, engine off. If it's anywhere between about .6V and 1.2V, leave it alone. Now, slowly open the throttle and see if you get a smooth increase in voltage to somewhere around 4.5V-5.0V at w.o.t. -- if so, your tps is working fine.
Try advancing your timing if you want to play with adjustments that will make a difference.
BTW, the computer will also adjust away most fuel pressure changes by using it's adaptive strategies to adjust pulse width and keep the O2 readings where it wants them - so don't go messin' with FP either.
"Recent Ford systems, all EEC since 1988, use a Rotary TP. The potentiometer increases resistance as the throttle shaft rotates. It is not adjustable, but the control-module programming compensates for any difference in sensors, readjusting to a base voltage when the throttle is closed."
Included in the discussion of the TPS function is a graph showing degrees of rotation vs. voltage output of the TPS. It should be a linear ramp where voltage is directly proportional to degree of throttle opening, starting at .601V at 0 degrees of opening, and increasing linearly to 4.538V at 85 degrees of opening, with a +/- 3 % variation allowed.
Interpretation - changing the initial setting of the tps won't accomplish a thing. The computer re-establishes a baseline when the throttle is closed. Check the initial voltage between the black and green wires with the engine warm, key on, engine off. If it's anywhere between about .6V and 1.2V, leave it alone. Now, slowly open the throttle and see if you get a smooth increase in voltage to somewhere around 4.5V-5.0V at w.o.t. -- if so, your tps is working fine.
Try advancing your timing if you want to play with adjustments that will make a difference.
BTW, the computer will also adjust away most fuel pressure changes by using it's adaptive strategies to adjust pulse width and keep the O2 readings where it wants them - so don't go messin' with FP either.
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