ECU reflash / throttle hesitation

[expatmanxman]

I have a dreadful throttle hesitation which has become a bigger problem since I started using my bike for MotoGymkhana, I need instant response or I might end up on the floor. I read in a post somewhere that you can get the ECU reflashed, anyone know exactly what that means, and a bit of a long shot is there anywhere in the UK that would/could do it.
I have a Power Commander III fitted but that hasn't made any difference, are there any other ideas for getting rid of this annoying glitch in throttle response?

 

[Motogiro]

Your PClll should be able to help you without a reflash of the ECU. Fueling with the Power Commander should be sufficient. First I would put the instrument panel in diagnostic mode and confirm your Throttle Position Sensor is operating correctly. Even when the TPS shows okay in the diagnostic mode it can be bad. Sometimes an O scope is the only good tool to see what's actually going on but that's another story. Search throttle control for the PClll. There is also a race mode for throttle that give instant response on throttle crack. Contact the support people at Dynojet for good info.

The Power Commander should be mapped on a dyno to really perform properly and any map that you upload to the unit may instead be a hinderence.

Here's a link that talks about TPS with the PClll. FJR Owners Website: Set Throttle Position for Powercommander 3 USB

 

[expatmanxman]

Thanks for that, will do some reading and maybe book in for some dyno time.

 

[lawlberg]

One other thing you can do is modify your throttle a little bit. I followed the direction of one of the Aussies on here (sorry it's been a while and I can't remember who) and put a small PVC sleeve between the throttle cable and the throttle tube, effectively shortening the tube (and in the process I wound up removing the slack in the pull - probably the more useful part of this) I'm sure you've tightened the tolerances on your cables, but just in case I figured I'd suggest that.

Most of the maps aren't tuned down low in the revs, you don't really notice it in normal riding, but for your situation, on off chop, it's definitely useful. Playing around with the map down there can definitely help, Obviously Motogiro emphasises getting it properly tuned, but simply adding fuel down low (talking 0-5% throttle open) should help with the response.

In addition - that race mode sounds awesome. Anyone else have more details about that? Could be neat.

 

[Erci]

In addition to fuel mapping, other things can make the throttle response worse. If the bike has good number of miles on it, things like spark plug replacement, throttle body sync and proper chain adjustment all can make a difference.

 

[expatmanxman]

Bike is in good condition, not too many miles, throttle cable slack removed, that idea with the sleeve is interesting as another thing I could do with doing is setting the tickover about 3000rpm, can't get that high with the idle speed adjustment. A lot to do to make it a really good MotoGymkhana bike.

 

[FinalImpact]

Bike is in good condition, not too many miles, throttle cable slack removed, that idea with the sleeve is interesting as another thing I could do with doing is setting the tickover about 3000rpm, can't get that high with the idle speed adjustment. A lot to do to make it a really good MotoGymkhana bike.

Lighten the top would be step one! - Perhaps side exhaust in front of the rear wheel and an expensive Li battery to drop some weight?!?

Raising RPM:
The more you raise the idle, the leaner the engine gets and its more apt to stumble off idle. The reason is this; the engine doesn't really know your adding AIR per say as its not an active throttle input when adjusted by the idle speed controller.

You see the TPS sensor isn't being moved so the ECM is not actively adding fuel, you're just adding more air. Yes, based on RPM the factory map is likely adding some fuel, but not in a "we need to accelerate" fashion. Make sense?

I'm not advocating you do this so this is a "AT YOUR OWN RISK" action as it comes with unforeseen complications just like turning the idle speed knob. The engine needs more fuel down low. So, you could bump the RPM by another, but you must add more fuel via the controller or its really just going to make it fall on its face off idle.

One option is you do the CO mode that allows the user to increase the fuel mixture, BUT you should be able to do this with the controller you have.


Next to idle speed adjuster is cold idle speed controller. It uses hot water from the engine to change the idle speed. Its factory set and I would advise not messing with it. But, if you must, it **may be** an option to raise idle speed. Again, it suffers the same fate as the screw in that there is a different fuel map for idle at 1200 RPM and acceleration from throttle input. It needs more fuel enrichment to pull this off or you're better off leaving it at 1300 RPM or so.

Remove cap, adjust this; KEEP TRACK OF WHERE IT IS so you can put it back (count turns and record data).

 

[FinalImpact]

Also - ECU-Unleashed is the name your looking for and it may be a quick fix for a healthy bike but it comes at a cost ~$500 in the US.

They will do a group by but its not much of a savings, I asked.

If your stumble is not a bad TPS as suggested above, you may want to look for vacuum leaks, or the actual vacuum sensor. If its failing in some way it may cause an issue like this.

You might look through this thread - its addressing vacuum leaks & idle speed. Posts 17 and 40 come to mind.