Throttle Sags: Not TPS?

[Wiggus]

I'm having the same throttle hesitations and sags (at about 2500, 3500, and 3900rpm) as reported elsewhere by Tiger owners on my 1999 885i Tiger. All symptoms point to a bad Throttle Position Sensor which is covered in the Sticky on this forum.

http://tigertriple.com/forum/index.php/topic,7620

But there are two clues that are making me think twice. If I do the Triumph 12 minute ECU reset (back to stock) it runs great for a while, then the hesitations slowly come back. If it's a bad TPS I wouldn't expect the reset to "fix" it.

Another big clue is that the bike was running fine after a reset, then I got poured on for about 5-10 minutes and the symptoms returned immediately during the storm. It slowly returned to normal after the rain passed.

Could it be some other sensor going bad that the ECU is trying to compensate for?

Also, does it make a difference to the ECU's "learning" if you shut the bike off at the kill switch instead of the key?

[EvilBetty]

Wow sorry no one responded to this.  Did you get it sorted?

[Wiggus]

Ha! All's quiet on the Tiger front.

No I didn't, though it's not been bad at all lately. It is still there a little till it warms up. I'm wondering if the way you shut the bike off makes a difference in the ECU's memory. Here's why. It seems that when I just use the engine kill switch the sags do not appear except for mildly. When I turn the bike off at the key the sags appear more quickly and are much worse. I wonder if there is a memory-saving cycle, where information is saved to memory, when the key is turned off that is skipped by using the kill switch.

Still doesn't get me closer to a solution though.

[Bixxer Bob]

Short answer is no.

Whether you use the kill switch or the key, the ECU does a save before shutting down.  Just listen to it in a quiet garage and you'll hear the click of the relay opening.

Edit: turn ign on, wait for startup cycle to finish (fuel pump run etc), hit kill switch and listen to ECU shut down cycle followed by relay click as it powers down.  Next turn kill switch back on, turn off using the key, hear the ECU shut down cycle and relay click again.

Well that's what mine does anyway....  :roll:

[Wiggus]

More and more baffling then....hmmmmm.