Tps (throttle Position Sensor) Adjustment

Discussion in 'Fox 5.0 Mustang Tech' started by MONDONGO-NICA, Oct 4, 2013.

  1. Hello all, i have 24lb injectors, a 70mm TB, BBK intake, BBK mass air for 24lb injectors, 255lb fuel pump. The car has had hesitation problems for months. I have been chasing down the cause and now I'm trying the TPS. I read somewhere that TPS (throttle position sensor )needs adjustment by turning it a little and it will send a different voltage signal. My voltage is .96v.

    My question is do i need more volts of less volts for my increased air flow?

    thank you.

  2. You don't need to do ANYTHING. .96 is about as close as you can get it. The TPS voltage is referenced during start-up and is scaled appropriately from there. The EEC handles it all by itself.

    Have you pulled codes?
  3. thank you it makes sense i will move on to another possible source of my problem.
  4. Pull codes
  5. You haven't pulled them, or you don't have any?
  6. i tried to pull some but none came up
  7. You should have gotten a code 11 if you did it correctly and the ECM was clear.
  8. Do oyu have any additional mods beyond what you listed? Heads/Cam/Intake? That's a lot of fuel for a stock engine if you are stock. I wonder if you are running rich and loading up and that's what the hesitation is? Do you have an adjustable FPR?

    You got no codes running the Engine off and engine running codes?
    #12 Mustang5L5, Oct 4, 2013
    Last edited: Oct 4, 2013
  9. whats the fuel pressure psi at??
  10. yes i did get code 11 but that's just a to say that the test ran successfully. ok so i ran the car around the block to warm it up and i tried to pull the codes again. this time i got code 96 ( fuel pump secondary circuit fault/ high speed fuel pump relay open). the TPS is at a solid .96v.

    Yes i have more mods 306 rebuild last year, ported Edelbrock heads, upper and lower intake+plenum, long tubes, electric fan, new steering rack. The smog pump seized two months after rebuild so it is bypassed.

    I got a good deal online for the pump that's why i got that one ~$45. My old one was making a lot of noise, had it tested and was told the pressure was low but i forgot how much it was making.

    Do not have an adjustable FPR

    So new mystery code 96 i swear it never ends.
  11. Meh... It's not that it doesn't end, it's just that you gotta get on-top of it. You will eventually. You do them right and they're pretty reliable cars.

    Your fuel pump secondary fault code is very likely related to the problems that you're having. So you've got an ebay, $45 pump in there right now? Who makes it, and how long has it been in there?
  12. i know it's just frustrating. i agree this code 96 is probably the problem. i don't buy anything on Ebay because i will always be wondering when it will fail. it was actually from American it was on sale at the time and i had a $50 coupon from when i bought the headers.
  13. I think that pump should be fine, that company has been around a long time. Did you preform the fuel pump test on the under hood test port?? Fuel pump relay is under driver seat or passeger fender near maf.
  14. What year is your car? There are two different wiring schemes for the fuel pump circuit, model years 1986-1990 and model years 1991 -1993. In order to post the correct code 96 troubleshooter, I need to know what year your car is.
  15. i replaced the under seat relay this afternoon i got it at autozone. it's an 89 mustang lx
  16. So far as I know, Edelbrock used re-branded Walboro pumps. Maybe JR can come up with some magic for the wiring.

    I still recommend that you put a fuel pressure test gauge to the rails. Ensure that the pump is priming correctly and that once you shut the key off, that pressure drops slowly on the gauge and not like a stone (bad regulator).

    Furthermore, if when you hit the relief valve on the pressure gauge, if you see lots of bubbles in the line (air in the system) then the pump is in fact, bad.