Hi all,

This is my first post here and unfortunately, it's not a happy one. I have a 2005 R6 with about 9000 miles. It started surging at idle during a track day last fall, and I've been stabbing at getting it fixed ever since. The bike is still rideable, but I know that it's something I needed to eventually get right.

When cold and on high-idle, things seem to be ok, but once warm, the bike surges at idle and sometimes when I've been riding for while or revving hard, it will surge through such a wide RPM range it just dies. I've looked at numerous things and can get the bike to idle perfectly if I unplug one of two sensors, the Intake Air Pressure sensor or the Atmospheric Pressure sensor.

The old Intake Air Pressure sensor tested ok as per the service manual, but I replaced it anyway, thinking that would fix the problem. Nope. Then I tested the Atmo sensor and it tested out of range high on the multimeter. I just received a replacement today (taken off a 2008 R6S, same part number), and it doesn't fix the issue either.

The vacuum at the intake sensor shows to be almost the same as at the #3 throttle body takeoff, slightly higher actually, so I don't think I have a vacuum leak. I also think if I had a vacuum leak, unplugging those sensors wouldn't help at all. I mean it's like a switch. Sensors connected, idles like crap. Sensors disconnected, idles great.

Anyone have any ideas?

Chris

Update. Removing the aftermarket slip-on (Level One Racing) and reinstalling the stocker fixes the idle issue. That still doesn't explain the out of range reading at the atmo pressure sensor. I wonder if the test range given in the manual is incorrect.

The LOR pipe is pretty much straight through. Would the drastic reduction in back pressure result in the idle surge behavior?

I have a PCIII (currently disconnected). Tried the LOR and Graves tune and neither fixed the surge. Would a custom tune do the trick?

Chris

Just talked to Yamaha and they confirmed that the 3.75 to 4.25 working voltage on the atmo sensor is correct, so my reading is out of range. I really have a hard time believing that this sensor is bad, even though it is a used item from an '08 R6S, but I suppose it could be. It's a $200 gamble to see if a new one fixes the bike.

Chris

Hey mate, have you tested the lambda sensor?