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Discussion Starter #1
Searched the forum and couldnt find the answer i'm looking for!

Can the infamous "fuel cut off at closed throttle" be mapped out using a PCIII?

I dont particulaly want a TRE/remove secondary butterflies etc, but the choppy throttle is a pain in the hole!

I dont care about popping/back firing either!
 

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Hi chum,

no you cant map it out with a pc3 but the dyno jet optimizer has really helped my bike low down and through the rev range to..its made made to deal with areas were your bike runs lean an boggy..
 

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The Power commander tunes the fueling by adding or subtracting a percentage offset to the fueling. When the throttle is closed, the ECU is sending 0 fuel to the injectors. A 100% of 0 is still 0. So no, there's no way to tune that part out with a power commander.
 

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Discussion Starter #5
The Power commander tunes the fueling by adding or subtracting a percentage offset to the fueling. When the throttle is closed, the ECU is sending 0 fuel to the injectors. A 100% of 0 is still 0. So no, there's no way to tune that part out with a power commander.
Cool, thats all i needed to know!

Thanks :wink:
 

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Although the TRE claims to keep some fuel going in to aid the closed to open throttle response...it may be worth a try and its not to expensive.

Im thinking a TRE might be of benefit to me in this area...ive also found for my gen 3 the dynojet optimizer useful.
 

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You can't eliminate the decel fuel cut with a Power Commander, but you can smooth out the transition when the injectors come back on.

At tiny throttle opening, you actually want the engine to make as little power as possible to smooth out the transition (so that the "bump" between injectors-off and injectors-just-coming-back-on is as small as possible).

Make it lean, lean, lean in that area ... Maximum-power air/fuel ratio is *worst* for snatchiness! And stock, it's too rich down there. You have to take out a lot to get it where you need it.

And don't forget that the area in question is LESS than no-load on the engine. (The rear wheel is back-driving the engine on the over-run.) I calibrated it by coasting down a large hill with an air/fuel ratio gauge showing me what was happening as the throttle was gently cracked open and closed at various engine speeds. Typical power commander maps have zero in the less-than-no-load regime at higher revs because it's hard to tune. That's a tipoff that whoever made the map, hasn't done what needs to be done to fix this.

It is a lot of trial and error to get this right, but it can be done!
 

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back to the tre solution then...stop the fuel cut.

i like your rolling afr test... although i think dynojet recommend an afr of 13.6 to 1 in these closed loop areas..

good reading at " tre v flies low end performance " check out the afr readings (on google)
 

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Only discussion that brings up concerns the ZX14, but that is a VERY different beast.

13.6:1 at cruise is too rich. Try 15.5:1. I'd like to use 16.2:1 but the Power Commander's interpolation between map points does not seem accurate enough to do that without causing issues. Lean won't break anything at such light load on the engine. Lean misfire is around 18:1. In coasting/overrun you want to be just short of lean misfire, that way the engine makes as little power as possible once the injectors come back on, but the above-mentioned crap interpolation means that aiming for 15.5:1 really means sometimes more and sometimes less, so that's about as close as you can go.

Lean-cruise tuning has been discussed before in these forums ... it works. Search for the term "lean cruise".
 

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i dont agree that the zx14 engine afr is any different to any other high reving sports motorbike petrol engine..
see the fuel maps for bmw s1000rr ...at ...s1000rrforum.com.. title:" power commander v afr tables "..

having worked out the tables with a dynojet technician his bmw bike is set to run using air fuel ratios such as 13.3 to 13.8 afr in various steps across the rev range for gears 1/2/3 ... 4/5 ...and 6

i do agree that for crusing yes you can run leaner ratios and that makes sense but ivans tre and dynojets optimizer work opposite to the idea of being lean especially off the bottom..

as you can see both the zx14 and the s1000rr are running approx mid 13's afr..

In short i believe that having fuels ratios that are close together around 13.6.. meaning theres no sudden dips or peaks in afr is the best way to run any sportbike engine..
 
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