1999 wont rev, 5 days to fix it

Discussion in 'Mechanics Garage' started by wiso, May 10, 2020.

  1. GreginDenver

    GreginDenver New Member

    Country:
    United States
    Joined:
    Mar 27, 2016
    Messages:
    503
    Likes Received:
    194
    Trophy Points:
    43
    Location:
    Denver, Colorado
    Map
    Now you've got my curiosity up.

    Most VFR owners are completely unfamiliar with the parameters of the bike's Ignition System. We (VFR owners) simply make sure the items related to the Ignition System are installed in the correct manner.

    And if I remember correctly, none of the performance add-on boxes (Rapid Bike or Power Commander) have the capability to change/adjust ignition timing.

    So I'm guessing that your 5th Gen doesn't have anything added onto it (no special performance boxes) that would be adjusting/changing the ignition timing (in other words, nothing is messing with the number of degrees BTDC, before top dead center).

    So if nothing has been added to the bike I would have to imagine that a messed up ignition timing would be the result of a malfunctioning input parameter to the Honda PGM-FI ECU. And the best candidate for that would be the Throttle Position Sensor. Or a grounding problem (poor path-to-ground somewhere).
     
  2. GreginDenver

    GreginDenver New Member

    Country:
    United States
    Joined:
    Mar 27, 2016
    Messages:
    503
    Likes Received:
    194
    Trophy Points:
    43
    Location:
    Denver, Colorado
    Map
    I say all of that because a 15 degree change in Ignition Timing isn't that much. On a modern, ECU controlled engine when you roll hard onto the throttle the ignition timing will be changed/manipulated by the ECU.
     
  3. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
    No other add ons installed. The ignition does advance as the rpms increase. I'm not sure the TPS effects timing. I think it just locates throttle plates so ECU can adjust fuel delivery.
    The pulse generator triggers the ECU to the position of the crank.
     
  4. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
    I have another ECU and pulse generator on the way..
     
  5. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
    I had the best mechanic I know go through the bike to verify everything and diagnose the issue.
    The previous owner was messing around with the electrical system due to charging issue, I think he may have damaged the ECU with his "advanced" electrical skills.
     
  6. GreginDenver

    GreginDenver New Member

    Country:
    United States
    Joined:
    Mar 27, 2016
    Messages:
    503
    Likes Received:
    194
    Trophy Points:
    43
    Location:
    Denver, Colorado
    Map
    Oh really? You're sitting there looking at the Service Manual, in chapter 17, the chapter that talks about the ignition system, with diagrams that clearly show the input parameters related to the Honda PGM-FI ECU's ignition control function, and "you're not sure" that the Throttle Position Sensor has anything to do with ignition?

    Okay, I'm out of this thread.
     
  7. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
     
  8. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
    If the TPS was bad, wouldn't it throw a error code?
     
  9. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
    If you reread my post, I said I wasn't sure the TPS effects timing. The TPS does in fact just locate the throttle plates for the ECU.
    Section 21-14 and 21-15 describe what the TP and IPG do.
     
  10. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
    Just because the ECU gets data from a sensor, doesn't mean that it is used to control the timing.
     
  11. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
    And, chapter 17 has no parameters in it at all about the ignition system.
    Glad you are "out of this thread"
     
  12. squirrelman

    squirrelman Member

    Country:
    United States
    Joined:
    Jul 27, 2006
    Messages:
    9,838
    Likes Received:
    743
    Trophy Points:
    128
    Location:
    Buffalo, NY
    Map
    CDI no good.
     
  13. raYzerman

    raYzerman Member

    Country:
    Canada
    Joined:
    Dec 3, 2019
    Messages:
    1,228
    Likes Received:
    450
    Trophy Points:
    113
    Location:
    Millgrove, ON
    Map
    Throttle position info is a necessary component for ignition timing. If the ECU doesn't know where the throttle is, how would it know when and where to adjust timing....... as you said, timing advances as rpm increases, which only occurs if the throttle plates move.
     
  14. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
    RPM is not provided by the TPS.
     
  15. raYzerman

    raYzerman Member

    Country:
    Canada
    Joined:
    Dec 3, 2019
    Messages:
    1,228
    Likes Received:
    450
    Trophy Points:
    113
    Location:
    Millgrove, ON
    Map
    RPM is provided by your right wrist, TPS tells the ECU where it is that produced that RPM.
     
  16. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
    I meant that the ECU doesn't get the info on RPM from the TPS. The ignition advances from RPM increase, not throttle position. The RPM is read by the Pulse pickup at the crank.
     
  17. raYzerman

    raYzerman Member

    Country:
    Canada
    Joined:
    Dec 3, 2019
    Messages:
    1,228
    Likes Received:
    450
    Trophy Points:
    113
    Location:
    Millgrove, ON
    Map
    Just for your info.... a faulty TPS can cause many issues... may not be your problem, but you'll find out eventually. Here is a Yamaha one that was faulty, though it appears great to the naked eye. The four-fingered wipers ride on a ceramic resistor board with two paths of variable resistance, ECU interprets that signalling. Honda TPS should be somewhat similar, but I never dissected one.

    20191217_171053.jpg 20191218_143630.jpg
     
  18. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
    Thanks for the info, Itcant hurt to test mine to be sure.
     
  19. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
    Honda test procedure requires a plug in box to check voltages from TPS. Which I do not have access to. So replacement is the option.
     
  20. wiso

    wiso New Member

    Country:
    United States
    Joined:
    Dec 15, 2019
    Messages:
    79
    Likes Received:
    6
    Trophy Points:
    8
    Location:
    upstate NY
    Map
    replaced TPS, ECU, pulse generator, cam sensor, timing is still off around 10degrees
     
Related Topics

Share This Page