06 XB9SX intermitent problem

[Cosworth]

I have already swapped in a known good ECM with no change.

Im getting readings from all the sensors so other than hard parts I just dont know what the deal is yet...

[Cooter]

When I first started working as a tech, everyone had one of those old skool oscilloscopes.
Man, I could diagnose something from across the room with one of those! It would tell you right away if your coil or CPS was breaking up with heat, or if the timing was going erratic, or if it was going lean.
Any access to a wide band o2 set up?

[Cosworth]

Ive changed coils (brand new coil) no change, ive changed cps no change.

It could be o2 fouled out at this point I wouldnt doubt it after digging carbon out of the exhaust port. The only wideband I have is hardwired to a megasquirt system. Ive been meaning to purchase a standalone anyway so may be a perfect time to pull the trigger.

I do appreciate the insight cooter.

[Cosworth]

Pulling out all the stops, Ive acquired a new wiring harness, new fuel injectors, and a new o2 sensor.

By the time im done replacing parts its basically a new bike lol..

[Cooter]

Oh my lord! I didn't re-read the whole thread, have you done any datalogging??

[Larry_XB12S]

To me it sounds like the rear coil drive wire from the ECM is intermittant. Before buying and replacing the harness try bypassing the wire with your own from the ECM to the coil.
Especially with everything you have swapped out.

[Cosworth]

Coil issues was the first thing I ruled out.

I swapped over the harness last Wednesday evening with no change at all. Bike still runs on two cylinders for up to 1 min then immediately cuts down to 1 and will not go back to two till it cools off.

-Fuel pressure is good
-Known good ECM has been swapped in
-Known good Coil
-New CPS
-New O2
-New Head temp
-Bike is charging correctly (when running right)
-New/old harness off a known running bike

It puts me back to thinking its a mechanical issue.

[user_deleted]

It puts me back to thinking its a mechanical issue.

i specifically mentioned this almost a year ago when you commenced with this thread...see first page. it is internal. you are losing compression during the heat cycle. most likely in the valve train.

[Cosworth]

Yes sir, I remember the post so I apologize if it seems like I just dismissed your advice that's not the case.

I did check compression and came up with a bad number on the rear so tore the top back down and had the heads done as well as new lifters. So I guess what I'm saying is I did not think to check compression again now while cold and again after the cylinder goes out.

If that's the case though it'd have to be
1 loosing oil pressure to let the lifters down
2 another set of bad lifters
3?????