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post #1 of 14 Old May 19th, 2009, 05:53 PM Thread Starter
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Symptoms of a bad TPS?

Here are my problems. I'm thinking I need to replace the TPS. Ideas??

1) Sometimes, when cruising at steady pressure on gas pedded at low speeds (20-30) the car lurks/bucks. e.g. does not drive steady, but feels like someone is pushing slightly up/down on gas.------making any change on gas peddel pressure fixes it at these low speeds.

2) At highway speeds, between 1500-2000 rpm I can push on the gas quite a bit before it will respond. e.g. can push the gas in/out a lot before you see any sort of change in engine rpm's or speed change.

Other than that car is fine. I'm sure it's not a fuel (filter, delivery, injectors, quality, etc) problem, for I maintain this car very well.

Funny thing is it did have similar problems when the DPFE sensor went bad....but it's new now. So, after my searching/reading manual the only thing I can think now is TPS......or **maybe** MAF????

Any advice is very welcome.

Last edited by PacificMustang01; May 19th, 2009 at 05:57 PM.
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post #2 of 14 Old May 19th, 2009, 05:55 PM
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so clean the maf and see if it helps out. That's free. Still sounds like a bad filter though.

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post #3 of 14 Old May 19th, 2009, 05:58 PM Thread Starter
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I'm about 99.9% sure it's not a filter problem. All filters are brand new, and I change ALL filters on regular basis.

Due to the sensitivity of MAF and high cost one were to fu*k it up, I don't want to do that unless it's last resort.

but thanks anyways.
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post #4 of 14 Old May 19th, 2009, 06:01 PM Thread Starter
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However, are these symptoms of dirty MAF also???

From what I've researched dirty MAF are a common problem on these cars.

Also, why is it the only problems I EVER have are sensor related????? I'm not complaining b/c they are always easy and cheap to replace, but damn! Can't they build better sensors? I've had two ford escorts (>200,000 miles on each) that NEVER had a sngle sensor problem.
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post #5 of 14 Old May 19th, 2009, 06:51 PM
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You don't necessary have to replace it get an electronic cleaner from autozone and you're ready to go.... but in some cases you may need a new one..


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post #6 of 14 Old May 19th, 2009, 06:55 PM
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Can you datalog the car? The best thing to do would be to graph the TPS to make sure there isn't a dead spot in it.


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post #7 of 14 Old May 19th, 2009, 07:46 PM
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Hope this helps explaining more about it.....
What is the TPS?

Sitting on top of your throttle body there is a sensor that relays to the computer the exact opening position of the throttle butterfly. In other words, how far do you have your foot into the accelerator pedal. In technical terms the TPS is a low-voltage potentiometer. Based on the position of the throttle and other factors given to it, the computer will decide how rich the fuel mixture will be at any given open throttle point.

Why mess with the TPS?

Well, based on the information given above it is easy to understand how important this sensor is to your Mustang's performance. It is important that the computer gives the correct air and fuel mixture at the right time. If your TPS is off (or bad), the information (voltage) that the computer gets will be inaccurate. The tuning procedures in this article are very simple and the potential for the TPS to be off is significant, so why not tune your car the right way and get the most out of it.

Details:

Tuning the TPS

When you tune up your Mustang (wires, plugs, timing, etc.), the checking/adjustment (if needed) of the TPS should always be included. You will need a Phillips screwdriver, a pin, and a voltmeter that can read low voltages accurately. Here is the procedure:

1) Loosen the two screws holding on the TPS, (The screws can be very stubborn, so make sure you have a good quality screw driver that fits snug and has a long handle for lots of torque, or you might strip the heads) just enough to able to swivel the TPS with force.
2) Pierce the "GREEN" wire with the pin and hook the positive (+) lead from the voltmeter to it.
3) Ground the negative (-) lead from the voltmeter. Use a good ground, like the engine or other grounded metal source.
4) Turn your ignition key to the run position, but do not start the vehicle
5) Rotate the TPS until you achieve .98 to .99 Volts (For stock or slightly modified engines).
6) Tighten the screws on the TPS and recheck.

Troubleshooting

If the maximum or minimum voltage you can obtain is close to the above recommended voltage setting (.98-.99), but the TPS just won't turn enough to get it right, you will have to modify the TPS. If you get a very low voltage reading, make sure you have an accurate voltmeter and your connections are solid, if so, you need to replace your TPS. If you have no voltage, you have a bad connection or a bad voltmeter. Rarely, if never, will a TPS be in such bad shape, especially if your car still runs good."


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post #8 of 14 Old May 27th, 2009, 04:32 PM
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Excellent instructions on checking the TPS. I'm going to do that tomorrow on mine. I've got the surging issue too, along with some others. I cleaned my MAF and it didn't resolve it.

My question since we are talking about TPS....and I think I know the answer, but I'm cheap. I noticed that my TPS wires rub against the bottom of my hood. So much so, that it rubbed the insulation right off the wires leaving the copper exposed. I wrapped it up pretty good in electrical tape.

I'm wondering if the insulation rubbing off could have damaged the TPS or if it is negatively affecting it. I'll try the voltage test. Can you just pick up those testers at Walmart, or some other store for cheap asses?

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post #9 of 14 Old May 27th, 2009, 04:34 PM
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Prolly autozone, hope it helps.... but is not always necessary to buy a new one, you can fix yours.


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post #10 of 14 Old May 27th, 2009, 04:42 PM
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I'm at "work" right now, so without being able to look at my TPS, when you say to "rotate" it, I'm a little confused. Turning a screw or the entire TPS?

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post #11 of 14 Old May 27th, 2009, 04:43 PM
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The screw lol


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post #12 of 14 Old May 27th, 2009, 05:08 PM
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I have the same problem with driving on the street/highway and hit the gas all the way down and it takes like what seems like 1-2 seconds before it will pickup the power. Although im thinking thats just because the auto is downshifting but it doesnt feel like it. And it doest do it all the time. Or sometimes I will already be in 2nd gear and hit the gas and takes a while.


I sorta always figured it was just because of the slow ass 3.8 LOL
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post #13 of 14 Old February 18th, 2011, 10:16 PM
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its not your tps

i just last month bought a 95 gt 5.0 134xxx and super clean in and out.anyway mine does the same thing. surging between 30-40 mph.so i had a diagnosis done,results weak distributor leaking egr valve,and tps.they did the distributor i did the rest,same thing surging 30-40mph.did some researching and came up with a maf sensor,everyone i talked to says just clean it so i did w/carb cleaner and tested.it felt a little better but same thing.i replaced the fuel filter,same thing.talked to some other people they thought it might be a slipping od belt in my tranny,so i took it to my tranny shop they scoped the tranny and all good there,but his scope did show a weak maf sensor,ill pick mine up tomorrow and let you know.its not your tps man.
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post #14 of 14 Old February 19th, 2011, 01:20 PM
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Quote:
Originally Posted by dscsyclone View Post
i just last month bought a 95 gt 5.0 134xxx and super clean in and out.anyway mine does the same thing. surging between 30-40 mph.so i had a diagnosis done,results weak distributor leaking egr valve,and tps.they did the distributor i did the rest,same thing surging 30-40mph.did some researching and came up with a maf sensor,everyone i talked to says just clean it so i did w/carb cleaner and tested.it felt a little better but same thing.i replaced the fuel filter,same thing.talked to some other people they thought it might be a slipping od belt in my tranny,so i took it to my tranny shop they scoped the tranny and all good there,but his scope did show a weak maf sensor,ill pick mine up tomorrow and let you know.its not your tps man.
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