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Thread: Possibly bad tps need some help

  1. #1
    Join Date
    May 2018
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    Irmo SC
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    Possibly bad tps need some help

    So having a studder issue when opening op throttle and random idol changes followed some post about checking tps so I metered the ~~~ wire and got 5.04 volts KOEOFF but it doesn't ever change no matter how I open the throttle body whick is a BBK 70mm so does this mean tps is bad?? I would assume thats what it means

  2. #2
    Join Date
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    Salem OR
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    I outlined a process to check TPS, here, if you haven't already seen it:http://www.sccoa.com/forums/showthre...w+to+check+tps

    Sounds, tho, like you're sniffing the 5.v ref., not the output to the EEC.

  3. #3
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    Absolutely no offense ment so don't take it wrong but do you (kmt) have another job only reason I say that is cause you're the 1st person to answer every question and and certainly appreciate you and your knowledge and willingness to help me so I think your right I was probably on the wrong wire as I do not have a evtm manual and basically am new to the Super Coupes so it is and has been a learning cure but thank you for the guidance I will check it based on what you said

  4. #4
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    I'm retired, love these cars, always willing to learn more about them, and happy to share info/give back to the community when I can. I've heard it's not so busy here as it is on facebook, as an example, but I don't spend time there, so...

    In addition to an EVTM, don't forget we can access factory wiring diagrams here on SCCOA. This is the link for a 1990 SC:

    http://www.sccoa.com/WiringDiagrams/...%20Diagram.pdf

  5. #5
    Join Date
    Apr 2011
    Location
    Brentwood, TN
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    185

    That makes 2 of us

    I am retired too, and do not spend time on FB. SCCoA is my "go to" place always. However, my hat's off to KMT as he is one of the real 'Ambassadors to the many' who come here for Super Coupe / XR7 knowledge.

    The wiring diagrarms I've found to be even more helpful than the already good EVTMs.

    Cheers

    Colonel Glenn
    '90 SC 5 Spd, Oxford White/Black Leather, 1 owner -- XB-70 - AV1
    '92 SC Auto, Oxford White/Black Leather, -- "Weed" - aka XB-70 - AV2
    '90 SC Auto, 35th, all options car, -- "Phenix Bird"
    '95 SC 5 Spd, OP White/Grey Leather, -- DLF's built SC -- "Mr. Hyde"

  6. #6
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    Well gentlemen the both of you are greatly appreciated and your knowledge is exceptional

  7. #7
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    Canton, GA
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    KMT has helped me quite a few times. Iím always amazed at how fast he responds to posts and how much he knows about every problem I seem to have.

  8. #8
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    Just measured tps following your instruction and I get. .8 with the throttle closed and 4.4 at wot that sound right of course this is Key on engine off

  9. #9
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    Sounds like you're doing it right

    What did you observe while gradually going back/forth open/closed? As long as the volts increased/decreased smoothly and consistently, with no sudden jumps/drops, I'd want to say that TPS is good.

    I have seen some TPSs act up under different temperature conditions, or break contact at far end of either swing, so keep that in mind.

    Remember, it's not about the -exact- voltage output at a given point with our cars, it's about the range between low/high that the EEC looks at.

  10. #10
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    It seemed to me as it was smooth as I slowly went from 0 to wot the volts changed consistently and also from wot to 0 so it seemed smooth to me I wonder what else would be acting up then.

  11. #11
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    Hmm, well...stutter - let me think.

    Let's go over the basics and see what the factory Emissions Diagnostics Manual has to say.

    Is your issue best described as:
    • rough idle
    • low idle
    • misses under load
    • hesitates or stalls on acceleration
    • lack of power
    • surges at steady speed

    Is the check engine light on and sorry if I missed it, have you pulled codes?

    How many miles on the BBK?

    What vacuum do you see at idle?

    I've got some ideas, but if possible I want more info first, thanks.

  12. #12
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    Most issue is under medium to heavy acceleration feels as if your slightly pressing the clutch but it certainly not coming from transmission cause you can audibly hear the engine change and no CEL until it studder the light will come on for about 2-5 seconds and go right back off last time I pulled codes didn't have anything about that there where some codes but unrelated not sure what they where now I don't have a way at the moment to vacuum test and don't know mileage on bbk bought the car with it already on I've driven the car aprox 300 miles so far

  13. #13
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    And by change of engine I mean rpm stops going higher momentarily instead of going up without accelerating as it would with a slipping clutch rps don't fall they just don't go up smoothly more of a jump as it climbs sometimes it does it very little other more haven't been able to pin a factor of what causes it worse times than others
    Last edited by 35th; 01-18-2020 at 10:15 PM.

  14. #14
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    Another thing I thought of fuel mileage is horrible aprox 100 or so miles to a tank....

  15. #15
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    Quote Originally Posted by 35th View Post
    don't have a way at the moment to vacuum test
    I just meant what it says on the boost/vacuum gauge in the cluster, at idle.

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