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Thread: Help please I give up TPS problem.

  1. #21
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    For the new low price of a more powerful upgrade is it worth worrying about measuring.

    https://www.scienceofspeed.com/index...tting-kit.html

    Honda book time to instal is just 1.6hrs, by the time you've tried measuring it you could have replaced it.
    Pride.

    1992 My beloved Red/Black manual NA1.😎
    1992 Chevy Lumina apv Rockford Fosgate sound system demo van.🙉
    2003 Hartge Mini Cooper S (2 x UK & 1 x European sound quality finals winner) 🏆 

    "The NSX's greatest victory was to WIN the 1995 Le Mans 24hr GT2 Class"
    ..............and guess what, it was a RED one but of course.  

  2. #22
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    Quote Originally Posted by metsuki View Post
    FRP= fuel pressure regulator?
    no i don't think so
    Sorry, typo, yes FPR.

    @Pride: Replacing the fuel pump takes much more than that stated time...
    I had bad luck with a Walbro 255 once, excessive noise, very annoying, I'd choose another brand.

  3. #23
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    Quote Originally Posted by goldnsx View Post
    Pride: Replacing the fuel pump takes much more than that stated time...
    I had bad luck with a Walbro 255 once, excessive noise, very annoying, I'd choose another brand.
    Thats the time my Honda dealer told me he would charge me for, so that's ok.
    My biggest concern for them though is releasing the no doubted rusted straps or bolts.
    As regards the pump I believe one bad egg doesn't make a bad batch.
    In fact I haven't read any bad reviews.

    I will report back once installed.
    Thanks anyway gold.
    Pride.

    1992 My beloved Red/Black manual NA1.😎
    1992 Chevy Lumina apv Rockford Fosgate sound system demo van.🙉
    2003 Hartge Mini Cooper S (2 x UK & 1 x European sound quality finals winner) 🏆 

    "The NSX's greatest victory was to WIN the 1995 Le Mans 24hr GT2 Class"
    ..............and guess what, it was a RED one but of course.  

  4. #24
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    Quote Originally Posted by Pride View Post
    Thats the time my Honda dealer told me he would charge me for, so that's ok.
    My biggest concern for them though is releasing the no doubted rusted straps or bolts.
    As regards the pump I believe one bad egg doesn't make a bad batch.
    In fact I haven't read any bad reviews.

    I will report back once installed.
    Thanks anyway gold.
    That's a good deal (for you) but not sure if the dealer is happy with it in the end because it takes more like 4-5 hours or so and we did it multiple times. The Honda workbook often underestimates the amount of time and the dealer has to cope with it.

    There have been a few reports with excessive noise of a Walbro fuel pump, it really p*ssed me off that I got a noisy one. After two years of bearing it I went with a quality pump, Denso again where you have 100 out of 100 and not 98 or 99 out of 100.

    All aftermarket fuel pumps draw more current than the OEM one. Double or more. The cars wiring can't cope with it really. I'd say they should measure the voltage at the fuel pump after installation. There are Denso fuel pumps out there which are said to be a replacement for the NSX fuel pump (also Denso) but the no. of the Denso fuel pump in the NSX is unique and can't be obtained in any shop. You can only buy the expensive full set at Honda... I know have a Denso Supra fuel pump which is 'lusty' for Amperes but I wouldn't have installed it in a non-boosted NSX.

    Back to the topic: I would strongly suggest monitoring the fuel pressure while driving to rule out any problem with the fuel pump/FPR.

  5. #25
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    Just returned another NSX to the owner so I have bit more time for this subject although already working on another one.

    Based on what you wrote so far on here and on NSX Prime, please refer to the followings.

    To prevent confusion, please use the following terms.
    TPS: Throttle butterfly/barrel Position Sensor, mounted at the side of the TH body. Used for 'w' mapping described later.
    ACP: Accelerator Pedal Angle Sensor, mounted at the bottom side of the TH body. Not much factor for EFI control.


    First of all, what was the reason to replace the TPS?
    Unless you triggered the CEL or accidentally broke off the connector (I know at least one owner did this....), no need replacing.
    Depending on the country spec, the screws are locked or tamperproofed.


    Please check your base idle rpm and most importantly, the base IG timing.
    You must disconnect EACV during the test and the engine must be able to idle fairly smoothly at 600rpm.
    If IG timing jumps around, you have other issues.


    Can you always create the same issue at any time of the drive cycle?
    In other words, does your issue only happen at the very beginning of the cycle or can you re-create it even after driving for a while, let's say even after 30min in to the driving?


    Any specific rpm range?


    Does it make difference if you slowly accerelate or open the TH pedal sharply?
    ECU uses angular velocity 'w' (omega) of the TPS signal to enrich the fuel timer during acceleration.
    It is also used for fuel cut but I'll leave it for now.
    The faster you open the ACP, the larger the 'w' of the TPS resulting in extra fuel into the cyl.
    ECU has its own mapping for 'w'.
    If you open the ECU, you will know what CPU is used and that will tell you the estimated performance.
    Also, count the number of trigger teeth on the front intake cam pulley.
    That will tell how many INT jobs can be triggered during the 720deg crank cycle and that is the limit of the ancient ECU performance.
    O2 sensor has its own responce delay as well.


    I think you already tried this but forgot your answer.
    If you disconnect both O2 sensors (yes, not just one bank but must disconnect both) but keep the TPS connected, does it make any difference even for a small change?


    When the issue happens next time, quickly look at the rear view mirror.
    Any white smoke?


    If you disconnected TPS, it will trigger the CEL and ECU will disable the 'w' mapping.
    For IP reason, I won't tell what the ECU is doing but under this condition, it will explain why your issue is fixed and also depending on the situation, your idle rpm will be higher.


    Unless you have data logger with wide band O2 sensor attached to each cyl (yes, all six cyl), monitoring the narrow band O2 signal voltage won't tell you much for this type of issue.


    It all depends on your answers to the above but I would first clean the INJ.


    I won't go too much in detail with the fuel pressure based on what you wrote so far but it's easy to check so just test it although probably you won't find any issues.


    You may need checking the amount of oil trapped at the VVIS chamber if the issue only happens at the very first hard acceleration or if you see white smoke at the back when the issue happens.



    Kaz
    Last edited by Kaz-kzukNA1; 09-08-2018 at 04:20 PM. Reason: extra info

  6. Default

    Thank you Kaz for the timely you are according to me and my car.

    First of all you have to understand I always drove the car with this issue, and most of all this is the only nsx I drove. It is very hard for me to know what is normal and what it is not. I even found a note on the buying honda bill from the last owner (bought used ten years ago from a honda dealer) refering to an issue similar as mine. They wrote something like "cleaning and tuning" to resolve the issue but I think they did not do anything. Maybe this car do not runs perfectly from years and years ago

    I replace the TPS because:
    it seems logical with my issue
    I red many honda thread where it solved similars issues
    When I unplug it everything comes back to normal
    The part is pretty cheap
    When I turned it it made a very light squeaking noise

    When the EACV is unplug I have a good 600 rpm idle
    If by it timing you are refering at injection timing, I do not understand how to check that

    I can replicate the issue any time even after two hours driving. The only moment I do not feel it is maybe the first 5 mn when the car is warming up.

    There is no rpm range, I can replicate the problem at light throttle above 140kmh feeling the car going like slightly back and forth. Maybe there'is even a rythm to it I am not sure

    I do not feel it at WOT but it doesn't mean it is not there unfortunately.
    I do not WOT the car very often because i feel the car is not at ease. It is just a feeling, maybe I am just dreaming...

    I do not understand the "trigger teeth" thing sorry

    TPS plugged in , I disconnected one O2 sensor and feeled the same issue
    TPS plugged in, I disconnected both O2 sensors and the issue seems to be gone

    I never saw smoke coming from my car

    Monitoring the O2 I was just surprised too see how it jumps from one extrem to the other all the time

    From what I saw when I cleaned my TH body , VVIS seems pretty clean an I saw most of the plates was there and tight.

    I am waiting for exhaust seals to arrive now. Then I will clean injectors and check fuel pressure (even if disconnecting the fuel regulator did not change anything for me)

    I am so happy you took some time to help me. I am hating this car right now and feeling like selling it would make my life easier. But every time I see it I love it again and I cannot sell it

    Merci beaucoup

  7. #27
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    Quote Originally Posted by metsuki View Post
    Monitoring the O2 I was just surprised too see how it jumps from one extrem to the other all the time

    I am waiting for exhaust seals to arrive now. Then I will clean injectors and check fuel pressure (even if disconnecting the fuel regulator did not change anything for me)
    Narrowband o2-sensor are designed that way. See here in comparison to a wideband o2 sensor: https://www.drive2.com/b/478329065720250675/
    If the exhaust is leaking they jump even more.

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