The more I think about this the more I am convinced the problem happens when the FI system cannot read engine MAP signals below a certain pressure. Either it maps them to zero or the value is just ignored as out of range. Opening the throttle more suddenly puts it in range and it surges. This could happen if the system digitizes a set allowable range of MAP sensor voltage values at start up based on ambient - max vacuum, but does not update them as elevation increases. Shutting off the engine resets this process and you're OK until you go up in altitude and drop below minimum allowable MAP voltage range again. If I were an emissions-concerned programmer, I would want to get the best digital resolution possible on my MAP voltage values, which would mean all the bits go to the narrowest voltage range possible, but if I forgot that ambient P varies a lot, thus MAP sensor voltage varies a lot, I'd see this kind of thing happen. And of course I'd commit sepuku.
Al,
I think you are pretty close to getting it right. One of my riding buddies has both an '07 FJR and an '06 FZ1.
We have finally 'fixed' his FZ1 (Ivan's FCE, PCIII, Timing module, Acropovic full exhaust system) but his FJR is
now acting up a LOT. Today it was worse than it's ever been. He was 3 minutes from the dealer when it got
REALLY bad. He finally had to do the ignition OFF/ON reset to get it to pull at all. It ran perfectly the rest of
the day. This was in pretty high temps (88-103'ish) and elevation changes from 2,500' to 5,000' and back to
3,000' or so. In the past couple of months we have done about 1,600 miles together with LOTS more elevation
changes and it only 'burped' once. The dealer has replaced the TPS once for this problem. The most recent
suggestion he had from the service manager was to "Adjust the Valves". This suggestion came from the
Yamaha Tech Support folks and was passed through the service manager. Not very credible in my opinion.
I think he is at 8,900 or so miles on his '07 and it replaced an '05 FJR which he had no problems with other
than the heat. Last 6 VIN numbers: 001834 AZ FJR1300A
There is one more thing that everyone is missing on the Atmospheric Pressure Sensor discussion. Not only
did they delete the Sensor up near the ECU but they also deleted the Pressure Regulator that used to be on the
end of the pressure sensing pipe above the throttle bodies. If you go to some of the parts Fiche and compare
the '05 with the '06 or '07
Intake 2 pages, you will see the regulator. I wonder if the quick variations in
Manifold pressure are confusing the ECU or maybe they are overflowing some register that they failed to
enlarge when they changed from reading actual Barometric Pressure to 'conjuring up' the value based on
Intake Air Temp and Manifold Absolute Pressure?
Parts Fiche from the Yamaha Site
https://www.yamaha-motor.com/sport/parts/home.aspx
'07 Parts 5JW-82380-00-00 SENSOR, PRESSURE (Item #17) Here:
https://tinyurl.com/2rgqs7 OR
https://parts.yamaha-motor.com/partimage.as...1&i=38371,2
'05 Parts 5JW-82380-00-00 .SENSOR, PRESSURE (Item #18) There are TWO of these sensors on the GenI
bikes.
https://tinyurl.com/2pdhxh OR
https://parts.yamaha-motor.com/partimage.as...1&i=84273,2
The other one (same P/N) is up near the ECU, (Item #30) Here:
https://tinyurl.com/34gte8 OR
https://parts.yamaha-motor.com/partimage.as...1&i=84271,2
Here is the Pressure Regulator I mentioned above: 5JW-13906-00-00 .REGULATOR, PRESSURE (Item #19)
https://tinyurl.com/2pdhxh OR
https://parts.yamaha-motor.com/partimage.as...1&i=84273,2
Without borrowing my buddy's service manual, I can't tell exactly where the old pressure regulator hose was attached
but it appears to go into the airbox. I'd love to get my hands on some parts and start experimenting. At first I would
just re-install the pressure regulator to see if it had an affect. I would probably need to install the older pressure sensing
pipe 5JW-13938-00-00 .PIPE (Item #8) and connect it as they did on the GenI bikes.
Another friend-of-a-friend claims to have fixed his altitude sickness by replacing the pressure sensor. He and
I were kicking ideas around a couple of months ago to cure his '07 of this problem. I suggested monitoring the
pressure sensor output with a good digital meter and then putting a vernier potentiometer in series with that
sensor to adjust it. He didn't want to mess with the pot so he replaced the sensor.
Just some random thoughts on the problem.
Mick