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  • MAXX TPS problem

    So I'm to the final stage of my A/n instal, and now I have run into what seems to be my final problem.

    The MAXX software recognizes the TPS, but it only allows me to get to 38% at the "low" end with throttles closed, and up to like 48% on the high end with throttles open.

    Also, the Pententioner won't adjust. It says it needs to be rotated left, but no luck when I rotate the TPS said direction - is there something that I'm not grasping with that?

    I bought this kit used off of a board member, and since have had to replace (actually, purchase) an air temp sensor, and now I fear that I'm going to be out the money again for a TPS. DON'T BUY USED! Now I understand why the person sold this particular setup.

    I'm pretty confident that I wired things correctly given that the laptop is recognizing some TPS activity.... that's why I think the problem is in the unit itself. Please help!

    Cheers,
    Ted
    1990 e30 m3

  • #2
    So I just checked the connector to the TPS in the harness and it is getting only 3.5 volts of power (so that is what is being fed to the TPS sensor), and I believe it should be getting 5 volts. Anyone have any idea why this would be the case or know how this would impact the situation?
    1990 e30 m3

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    • #3
      OK...correction.

      I am getting the full 5 volts to the TPS. I am getting 5 volts exactly at the high end of the spectrum, and 1.98 volts on the low end of the spectrum.

      From what I gather, this should give me my zero value voltage for the TPS (1.98 volts) and my WOT value in volts (5v) for my MAXX software to be able to recognize WOT an zero value... thus allowing it to understand it's percentage of throttle based on that range.

      I tested this two ways:

      1) I simply grounded the volt meter and tested the harness (which reads 5 volts). That's what it is supposed to be getting, so I am sure this is OK.

      2) I simply put two thin wires into the holes in the wiring harness, and then slid the TPS sensor into the socket. I then checked the volts again, and they gave me the lower and upper bound that I believe I am supposed to have.

      So here are the two problems I have identified:
      - When I get the TPS on the throttle shaft... there is not change in voltage as I open and close the throttles - as I believe there should be given that this voltage change is what tells the MAXX software about the throttle position.

      - When I go online with the MAXX software, as soon as I go online the system says that I am at 38% throttle and 40% of something else. At no point when the computer is "online" can I get either of those values to zero out. Is this a software problem? I have dumped the old map that was in the MAXX system and put in the 2.5 base map hoping that might help... but nothign changed. Is there a wiring problem that could cause this?

      Thanks for reading the long post. If I can solve this, hopefully with some help or otherwise, maybe this thread will be useful for someone else in the future.

      Cheers and happy Thanksgiving,
      Ted
      1990 e30 m3

      Comment


      • #4
        Check the operation of the TPS off the vehicle. The output should go from about .8 volts to about 4.6 volts. If the operation off the car is OK, then double check the wiring in the vehicle. 1.98 volts = about 40% throttle.

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        • #5
          ^
          Thank you!

          That is exactly what my car is reading... 1.98 volts = 38% throttle = 40% output. That is what my MAXX is reading with the TPS both installed and uninstalled. Is this the default reading?
          1990 e30 m3

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          • #6
            Disconnect the TPS output wire from the MAXX and check the output with a voltmeter. Sounds like it is wired incorrectly.
            Is it mounted properly on the throttle shaft? Do the idle and WOT contacts function correctly?

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            • #7
              I'm going to double check the wiring right now. The ICV percentage in the perameters control is bouncing between 43-45% with the car off.
              1990 e30 m3

              Comment


              • #8
                definitely check your wires, it sounds like it could be an electrical problem. That TPS is pretty bulky and IIRC it butts right up to the fuel pressure regulator. Are you sure that you can't turn the TPS more when calibrating? On one of the cars I installed MAXX on the TPS was very tight up against the FPR and it was actually really hard to rotate it into the properly calibrated position. How's your clearance?

                Comment


                • #9
                  The MAXX TPS is indeed bulky.... as per 1990 m3, mine is pretty tight against the fuel pressure regulator... you may need to make sure that the fuel pressure regulator is not preventing you from getting the needed clearance. Are you truly going ONLINE when checking the measurements on the Maxx? IIRC, the adjustment is done OFFLINE with the key in the vehicle ON, in position two (all the lights on the dash illuminated, but without starting the car) . FYI... the throttle percentages, never ZERO out.

                  in the idle position, mine reads about 12%, and with the throttle completely open, mine is at 94-95%.. Even though the thottle reads this way in the setup screen, i have seen 96% throttle while tuning and datalogging.
                  Mark Williams
                  Dallas, TX

                  Nothing says "welcome to the neighborhood" like a search... oh wait... looks like they are all gone! :rastajake:

                  sigpic

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                  • #10
                    M3Adjuster,

                    Does your throttle open fully - just that the operator when mapping mine started at idle then worked up to WOT. He then couldn't get the WOT value, so I had to move the accelerator throttle stop ( a small nut which locks located to the left of the left side of the throttle bodies looking from the front ) to get WOT i.e more movement for TPS.

                    Cheers,

                    Comment


                    • #11
                      Originally posted by M3 Adjuster View Post
                      The MAXX TPS is indeed bulky.... as per 1990 m3, mine is pretty tight against the fuel pressure regulator... you may need to make sure that the fuel pressure regulator is not preventing you from getting the needed clearance. Are you truly going ONLINE when checking the measurements on the Maxx? IIRC, the adjustment is done OFFLINE with the key in the vehicle ON, in position two (all the lights on the dash illuminated, but without starting the car) . FYI... the throttle percentages, never ZERO out.

                      in the idle position, mine reads about 12%, and with the throttle completely open, mine is at 94-95%.. Even though the thottle reads this way in the setup screen, i have seen 96% throttle while tuning and datalogging.
                      Mine is right on par with the 12%-96% range. I think it reads 12% at idle and 96-98% or so at WOT. It's been a few years since i played with mine though...haven't really messed with it since the dyno tune.

                      Comment


                      • #12
                        Had the same problem here installing the Maxx system. Turned out, that the throttles were not opening up all the way with the accelerator down (no wonder!). After replacing the grommets and adjusting the cable, I was able to reach 96%.

                        88 M3 - LACHSSILBER/M TECH
                        89 M3 - ALPINEWEISS II/SCHWARZ
                        85 323I S52 - ALPINEWEISS/SCHWARZ
                        91 M TECHNIC TURBO - MACAOBLAU/M TECH


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                        • #13
                          Originally posted by Reelizmpro View Post
                          Had the same problem here installing the Maxx system. Turned out, that the throttles were not opening up all the way with the accelerator down (no wonder!). After replacing the grommets and adjusting the cable, I was able to reach 96%.
                          Yes.. I am sure a lot of people have found that their throttles were not opening due to installing a MAXX set up. New grommets (if needed) are very inexpensive ($4-7), however most people simply need to use a pair
                          of open end wrenches to adjust the cables.

                          Jeff Krause (when he was in the Hoosier chapter) would come up to new members (that owned E30s) at BMW CCA meetings and ask if they would like 10 FREE horsepower. He would grab the 17 and 19 (iirc) wrenches from his trunk kit and then have them step on the accelerator and see if their throttle was opening up all the way... Whether or not one has a MAXX setup... if you don't KNOW that the throttle is opening up all the way, go to the garage and check it now! :cycle:
                          Mark Williams
                          Dallas, TX

                          Nothing says "welcome to the neighborhood" like a search... oh wait... looks like they are all gone! :rastajake:

                          sigpic

                          Comment


                          • #14
                            Alright guys... So it was indeed a wiring problem. I wired the three Gpot/Harness #7/D wire together instead of doing it properly.

                            I also ordered a new TPS yesterday and it got here today. Turns out, the old one was indeed causing problems. I now read this with the TPS instaled:

                            Idle = 12% throttle at .89volts
                            WOT= 89% throttle at about 4.49 volts

                            Does this sound appropriate or acceptable for the parameters? Someone previously mentioned it should go between about 12% and 96% so I am a little low on the top end but hopefully I can play with it a little bit and get it a little higher... I saw 93% earlier so hopefully I can achieve that again.
                            1990 e30 m3

                            Comment


                            • #15
                              If your accelerator cable is 20 years old, you may want to buy a new one for $26. I was able to adjust my old one to only 85% at full WOT (it was too stretched). I bought a new one and was able to get 94%.

                              If your cable is still good, you should be able to adjust it to 93% at least.

                              - gabor
                              October 1987 build date.

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