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· Gone
673 Posts
Discussion Starter · #1 · (Edited)
Right, first off this is only applicable to first gen 10R's as thats what i have and been working off the service manual for. Sorry if it an epic lol just tried to explain everything as clearly as i understand it in my (crazy) head.

I've done this research as to run my new airbox (qb carbon superbike) i'll need to remove the subthrottle actuator and subthrottle position sensor to gain the clearance it needs. (airbox bottom is lower and swoops down forward just over cam cover) I removed my secondaries a while back but left rod and motor alone. So over winter these will be coming off along with the rod that will be coming out and holes epoxied too ect.

Obviously everyone knows the removal of the actuator and postion sensor causes an error code (fi light) but what does that mean to the running of the bike? Will it make the bike run in a 'safe' mode? For example if one of the coils were to fail/short/left unplugged the ecu then also shuts down the injector on the corresponding cylinder. As to what we're interested in (subthrottle system) - here are the answers... (following lifted from the manual)

1: Service code 32 - subthrottle sensor malfunction - wiring open or short (we'll take this as open/ unplugged)

Backups by the ECU - If the subthrottle sensor fails (signal out of range/wiring open or short) the actuator locks subthrottle valve at the full open position.

2: Service code 62 - subthrottle valve actuator - the actuator operates the open and close of the subthrottle valve by the pulse signal from the ECU.

Backups by the ECU - If the sub throttle acuator fails (signal out of useable range/wiring short /open) the ecu stops current to the actuator.

The manual says the subthrottle position sensor is 'a rotating variable resistor that changes output voltage according to throttle opening. The ECU senses this change and determines fuel injection quantity, and ignition timing according to engine rpm and throttle opening.'

So this is what i reckon:

If we remove the secondaries, it throws the fueling out (sort with a pc3 or similar) as the ecu thinks everything is still there and working so fuel quantity/ign timing stays the same. (but some people still have had holes in their power curves with pc3 mapping)
So If we were to unplug the subthrottle sensor too - (Yes it will throw a fi light) then it will lock them in the fully open position, (which is what we've basically done by removing them) and use the corresponding 'fully open' fuel quantity/ign timing maps in the ECU. (according to the 'variable resistor' bit above) As for the actuator if its not there then it just stops the current.

This could be the missing link in getting the fueling on the right path once secondaries have been removed as the ECU will match the fuel quantity and ign timing with them being in the fully open position/removed on top of what the pc3 is doing. (as in you can get the afr right via pc3 with sencondaries removed but if ign timing is out then it won't burn as much fuel/make as much power as it could with the right ign timing - Doh!)

I'm going to try this out and see what i can feel before putting my new air box on but would be better to try it on a more stock bike as regards to exhaust system and velocity stacks so the changes are't masked out by other mods. My bike has a Motty AFR tuner with wideband lambda sensor so tunes itself according to what changes you make as you ride along (similar to Garth's) but can be bypassed so i can run the stock fueling, should notice it more then as to what changes the bike's ECU is doing. As for the full akra evo 2, well don't fancy swapping headers back over lol...

As for testing weather not very good over here in england at the moment with winter on the way so may be a while...

Unless there's a first gen owner out there with a stock bike less secondaries who (at their own risk lol) be willing to unplug their subthrottle sensor go for a ride and post back :)

Feel free to comment as all this may be bollocks or if there is someone more knowledgeble out there (like garth, bludevil etc) perhaps an opinion on all this waffling. But this is only my opinion/interpretation of the service manual... :badteeth:

Peace out.

· Registered
1,689 Posts
Thats an excellent observation/idea. Curious to see how it turns out with your setup.

On my 08, I didn't notice much change in the Bazzaz Autotune maps before and after removing the secondary flies. The differences were similar to the slight temperature changes.
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