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Old 12-09-2012, 09:08 AM   #6509
Joined: Sep 2008
Oddometer: 8
I posted a separate thread, but it go no love so I thought I'd try in this one for some ideas.

OK guys, I've got a tough one and I'm looking for suggestions on what else to check or try.

Background: 08 690 SMC 18k miles. it's had an intermittent problem for a while. FI light would come on while riding and bike would go into a limp home mode and run like crap: exhaust would get super loud and bike would buck and jerk when applying throttle. Exhaust would also get really hot. Turn off the bike, restart and problem would go away. checked the blinking FI light code and it put out 9 blinks - manifold pressure sensor circuit out of range. checked sensor, connection everything looked fine, problem keeps occurring. Replace sensor and intermittent problem still occurs during rides and goes away after restart. realize 9 blinks can also be atmospheric pressure sensor value out of range. unplug, clean connection, everything looks ok, put it back. problem goes away for a few months. problem comes back. I recheck atmospheric pressure sensor again and such but problem keeps occurring randomly then seems to go away. Problem comes back in august before a big ride. I decide to just replace the Atmospheric pressure sensor. New sensor comes in the day before the ride. I replace it and try it out for a bit and problem seems gone. 1st day of big ride, bike does it again. restart the bike and problem doesn't show up again until this month. Trying to ride home from work problem repeatedly shows up and now does it immediately after starting. I figure probably a good thing if it's not intermittent anymore because I should be able to track it down. stop at a railroad crossing for a train, pull over turn bike off and wait till train and traffic clear up. start up bike and it runs fine all the way home. I go out to start it up later to check it out and the bike does it again, perfect.

here is what I have tried so far:
got out the laptop with tune-ecu on it and hook it up. it shows code P0108 which is either Manifold absolute pressure 1 sensor circuit high voltage (bank 1) or Ambient air pressure sensor circuit high voltage. I look at the reading in tune ecu and it shows the map sensor reporting back 5v. I check with a pin and a multimeter to the signal line coming from the map sensor going into the ecu plug and it reads just under 3v. I also check out the APS and it reads just under 4v. both are within spec of 1-4.2 volts for these sensors. I try unplugging each sensor one at a time and verify no voltage coming in on either sensor signal line and tune ecu always reads 5v for MAP sensor. I run continuity tests on all wires running from the ecu to each sensor and everything looks fine. I figure it must be an internal short inside the ecu. I take my ECU and try it out on another bike and the bike runs fine and doesn't have any issues. I plug the ECU back into my bike and the proble still exists. Now I'm stumped and don't know what else to check. Oh, and I also cleaned all the ground and positive terminals I could find, starter relay terminals, starter terminal, and 3 frame grounds.

Anybody got any ideas?
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