Throttle Position Sensor Question

XXBULLETSXX

XXBULLETSXX

New Member
Mar 30, 2005
301
0
0
Kannapolis, NC
#1
Today my brother brought a code reader with him when he came to my house and we hooked it up to my OBD2 port and got a funny reading from my TPS. Here's the deal, my TPS is not registering 100% when the pedal is on the floor. It reads 91% when the pedal is on the floor.
My brother is a big chevy guy and says on the LS6's he builds they get that sort of thing all the time. Basically they bend something to allow the throttle body to open fully, "problem sovled" he says.
But he also said it could be a calibration problem.

Has anyone else had a similar problem with their TPS and if so how'd you correct it? I'm worried this is stealing power from me when the pedal is on the floor.

Yes I know my brother should buy a Ford, but I can't give him any crap because the engines he builds for Daytona Prototypes are currently leading the points race. So I get asked how Fords are doing each time I try to hang crap on him for being a chevy guy. But every now and then I get a few good jabs in. Anyways, let's focus on my faulty TPS.

Thanks!
 

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#4
XXBULLETSXX said:
Today my brother brought a code reader with him when he came to my house and we hooked it up to my OBD2 port and got a funny reading from my TPS. Here's the deal, my TPS is not registering 100% when the pedal is on the floor. It reads 91% when the pedal is on the floor.
My brother is a big chevy guy and says on the LS6's he builds they get that sort of thing all the time. Basically they bend something to allow the throttle body to open fully, "problem sovled" he says.
But he also said it could be a calibration problem.

Has anyone else had a similar problem with their TPS and if so how'd you correct it? I'm worried this is stealing power from me when the pedal is on the floor.

Yes I know my brother should buy a Ford, but I can't give him any crap because the engines he builds for Daytona Prototypes are currently leading the points race. So I get asked how Fords are doing each time I try to hang crap on him for being a chevy guy. But every now and then I get a few good jabs in. Anyways, let's focus on my faulty TPS.

Thanks!
Click to expand...

Check this http://www.mustangworld.com/ourpics/fcar/99pedals.htm

I bought the aluminum spacer from Modular Depot, IIRC, but I lost the link.
 
#7
propellerhead said:
http://www.cardomain.com/ride/593952/7
Click to expand...

Thanks Propellerhead! Wicked cool mod....you truly lived up to your name with that project! Thanks for forwarding that on and for posting it on cardomain! You should repost that mod on stangnet and let's make it a sticky. From the sounds of it, this happens to a lot of stangs and those who don't know about it just haven't figured it out yet.
 
#8
Help me answer this before I do the mod that propellerhead sent me. While a friend was over I stepped down on the gas all the way and he checked under the hood to see if the throttle body was bottomed out and sure enough she would not turn any further.
How do I fix it? I want all my throttle!! Waaaaa :fuss:
 
#11
Ok, check this out, the friend who helped me check if the TB arm could rotate any further brought his 03' Cobra over and we hooked up that same code reader to his car. Guess what? Same problem. The most he could get was 93% and he was really standing on it. LOL
I'm starting to wonder if this isn't something Ford has done. I'm going to do some more investigation tonight. I plan on removing the CAI from the TB, disconecting the throttle cable, hooking up the code reader, and visually checking that the throttle body is opening all the way. If not I plan to modify it until it will open all the way!
I'll keep everyone updated as to what I find out since this seems to be a problem with a lot of stangs.
 
#12
Is this a problem looking for a solution, or the other way around? I mean, what is the problem you are trying to resolve? The fact that "we hooked it up to my OBD2 port and got a funny reading from my TPS"?
 
#13
I think he's trying to say that accordingly to the scanner tool, when he puts the pedal all the way to the floor, the reading shows only 91 percent of full throttle, and not 100 percent. It could be that the scanning tool you are using isn't completely effective or it could be you have a slight bit much slack in the throttle cable. I've heard mixed results about the throttle cable spacer. Some people like it, and others do not. I guess its really up to you if you want to try it or not. I say since its only a few dollars for the parts, give it a try and see what you think. Let us know how it goes.
 
#15
Ok, I think the Code reader was incorrect. What I did last night was remove the CAI tube to see into the throttle body. Then I disconnected the throttle cable and manually turned the throttle arm. Once I did that I could see that when the arm reached the same position as when the cable was pulling on the TB arm (bottomed out with the flange against the TB body), it appeared as though the problem was with the calibration of the TPS. So I loosened up the TPS and with the Code Reader hooked up I tried to adjust the TPS until it would read 100% at WOT. But I was unable to get that much adjustment from the clearance holes in the TPS. Not even close! So I went back to what Propellorhead said about checking it with a voltage meter. It took a bit of research to find the two correct wires, which are the bottom two if memory serves me, that would give me the correct voltage readings so I could set it up the to read the way Propellerhead mentioned. I set it so the voltage readings were 0.97 at idle and 4.6 at WOT.
After all that was completed I started the car and it seemed to run fine.

However, when I drove into work this morning the engine was idling at 1650-1700rpm. So clearly I have some work to do when I get back home tonight. I need to figure out if I need to re-calibrate the TPS or just turn the idle down until it's idling at the correct rpm. I haven't made my mind up as to the correct way to approach this. But I'm leaning towards re-calibrating the TPS because it idled fine before I screwed with it and now it doesn't. But the TPS is set the way I read it should be from propellerhead and also from ModularPowerhouse forum so I think it’s correct. Possibly the mistake I made was that the engine was cold when I made the adjustment? But I think it’s that the TPS is forcing the idle up because it is bottomed out inside which is holding the TB open just a little. I think I will back it down a slight adjustment and see if that fixes the problem. Any thoughts you all may have on this would be helpful.

I’ll keep you all updated as to what happens. Sorry I didn’t post last night but I was way tired and went straight to bead the moment I finished. I’ll try not to let you guys down like that again but I can’t promise anything! :D
 
#17
To my knowledge and to my textbooks from school it should never reach the full 5 volts. You have to take into account the resistance in the components and in the wiring which usually should be no more than .5 of a volt. I believe there is a procedure to adjusting the tps sensor...I will get the proper procedure from the Mitchell computer at the job and have them posted for you tomorrow.

If anyone has any requests on specs from the dealer manuals let me know and I will get them posted as soon as I can. ;)
 
#18
Well I have it fixed. I had to put the TPS back to approximately where I had it before. I wasn’t able to do a voltage check on the TPS because I didn’t have an extra set of hands to help with the volt meter while I adjusted the TPS. But that led me to find out something curious. I found out that if I over tightened the mounting screws it would deflect the TPS and cause the engine to rev up until the screw was loosened.
Conclusion: I set the TPS with the car running and turned it to the point right before it would cause the engine to rev up. Then I tightened the top screw and then slowly tightened the bottom screw to just snug, not to tight. BTW it was the bottom screw which would cause the deflection problem that caused the engine to rev. Also, I don’t really know if the screw was actually causing any deflection but it was the only thing I could think that would cause the engine rev when “over” tightened.
If I decide to do any further adjustment to my TPS I’ll repost any additional information I come across.
Thanks for all your help guys it helped a lot!

Now get back to work! :cheers:
 
#19
the tps on my car isn't really designed to be adjusted. I'm assuming that 01 and up are the same. The 5.0 cars had slotted holes so it could move a little more. The way to set is by voltage between .997-.999 volts with the throttle closed. If the voltage goes above 5 volts the tps could be bad. glad the problem is gone.
 
#20
forpit2000gt said:
the tps on my car isn't really designed to be adjusted. I'm assuming that 01 and up are the same. The 5.0 cars had slotted holes so it could move a little more. The way to set is by voltage between .997-.999 volts with the throttle closed. If the voltage goes above 5 volts the tps could be bad. glad the problem is gone.
Click to expand...

I'm not following you, do you mean that you adjust the voltage going to the TPS? If so, how do you do that? I basically played with it using the slop in the clearance holes for the screws which mount the TPS to the throttle body. But if there's an easier way please let me know.
Knowing my luck it will take an $800 program to do it really simply. :doh:
 
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