DTT Failure?

[Airglider]

 
I took my bike up on the Parkway yesterday and wound it out, momentarily. I hit 5800 rpm and it started bogging down and running rough. It seemed to be running on one cylinder and the other cutting in and out. I was able to limp it home (approx 5 miles). I got about a mile from home and it smoothed out and ran fine.

When I got it home, I pulled the log file and was appalled to see the AFR's went severely lean. At the end of the log, readings were relatively normal.

During the period it was running rough, the IAC was reading 21, head temp went to 150F, AFR was 19. Once I got home, it idled at IAC= 29-30.

Today I went investigating. I found the TPS value at .2 volt. I was not able to adjust it. I tried an old one I had taken off during normal service and tried that - same result. It would take turning the throttle to a value of 6% to get a reading of .4V. Both TPS's have had the bushings removed and elongated. Plugs were tan on the electrodes. Base was black (both).

Does anyone have any suggestions or comments?

TIA

Airglider

PS  Recently went to Woods 6G at 10:1 compression. 400 miles on build. 188 ccp rear and 186 ccp front.



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[Airglider]

I spoke with Chris Schroeder yesterday. He was very helpful and suggested I try replacing the TPS as that is the weakest link in the system. I had already been to the dealership and ordered one as they did not have it in stock. It will take a week to come in. He also suggested I check the throttle plate/ shaft in case that broke.

I will reload a previous map in case there was a glitch that caused this problem.

Wish me luck.

AG

[-SeabrookTrickBagger]

Assuming it runs fine now, take it out and repeat the run at 5800 rpms.  See if it happens again.  Is so, see #2 below.  This assumes your map is developed since if it is not, you could have fouled the plugs and it might take a few miles for them to clean themselves.

1.  If the new TPS and/or map download does not fix it, then

2.  WAG:  intake manifold air leak.

Cylinders stretched/grew/lengthened (which increases distance between both heads) when you wound it out (heat too) causing the intake manifold to lose its seal on one or both heads at intake manifold to head interface.

Easy to check.

Could be a couple of dozen other things, too. 

Don't tell anyone, but I ran my bike by accident with the TPS sensor disconnected and it ran just fine ----- probably had it in open loop --- don't remember.

[Airglider]

Went to replace the TPS today and wiggling the throttle shaft, it came off into my hand. The shaft had fractured at the left butterfly screw. A new throttle body assembly is on order and hopefully I will be back on the road by the middle of next week.

AG

STB : Thank you for your insight.

[-SeabrookTrickBagger]

I have a butterfly which looks like a taco  --- bent almost in half.  It broke at the same place as yours, caused a backfire and I now have a butterfly suitable for framing.

[Airglider]

Still waiting on the new throttle body. Called the dealer today and they said it comes from Delphi. Hope it gets here soon.

AG