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SP2 - TPS or ECU? Tell me what's wrong...

4K views 18 replies 7 participants last post by  KoleDeRacer 
#1 ·
Hey guys / gals,

Quick update on any previous threads:

ITS ALIVE

Many thanks again to members here with help and parts. It ended up being a combo of a FPR / Coil / Plug problems. To top it off my fuel pump died in the middle of all that troubleshooting, so it's been a long road. I didn't let the bike win though ;)

It starts and idles fine now.

However, I'm not out of the woods yet: Sometimes, when I crack the throttle just a little bit, it jumps to 5k rpms and sits there. Like, even when I let go of the throttle, it'll sit at a solid 5k for a bit and then eventually drop back down to idle. When I say solid @5k I mean a 10 second or more rev. Randomly happens too.

It's a little unsettling, and I'm afraid to really ride it hard in the twisties if it's going to act that way.

Throttle cable is lubed, checked the action on it, not sticking.

Due to previous issues with the bike, it's as stock as it can be right now. Still have the TurnOne carbon box, but OEM exhaust, no PC3, solid battery.

Thoughts?
 
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#2 ·
Just thinking out loud here, but maybe the contacts need some cleaning around the TPS? Or since I still have that ridiculous airbox, maybe too much air? Should I hook the PC3 back up and see if that solves it? Hmmm.
 
#7 ·
Linkage and cable routing are good to go.

Throttle bodies close correctly.

I had it start, idle, then when I just barely started to move the throttle, it jumped to 5k, sat there, then came back down and eventually died. The throttle and rpms seems real jumpy.

Upon restarting, the bike felt like it was going to fire, and right before it caught it 'reset' almost like a weak battery.

I have one of those LiFe lightweight batteries. I started googling and found that some bikes (like ours) don't get along well with those. Anyone seen an alien motion battery wreak havoc like this?
 
#8 ·
The RC51 takes a lot of power to start and run.

Something i have found especially true with 1st gen fuel injected bikes.
If you have a regular battery i would try and start and run it with that first.
 
#10 ·
Tested with standard battery. Same behavior. The bike will stumble around at 2 or 3k like it's 'hunting' if I'm holding the throttle steadly, or (occasionally) rip itself up to 5k and hang there. I literally was watching the bike rev itself, throttle closed, standing there scratching my head.

Out of curiosity, I pulled the plugs out of both cylinders. They were both black, sooty, smelled like gas. The rear plug is now fouled. I have two FPRs I've tested, so I know it's not that issue.

I'm really starting to lean on TPS/Throttle body at this point: 'hunting' for revs, essentially revving itself to 5k for no reason, dumping fuel in both cylinders. Hell, how else would the bike get to 5k with a closed throttle plate? I envision raw fuel just getting blasted into the pistons.

Unless someone has another idea or wants to blame the ECU? I have a spare throttle body I bought a while back so I might get cracking on this. At least I'll know this bike top to freakin bottom soon...

Hell this could have been my problem in the first place.
 
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