EFI Information - Let's arm up!
 

How bout some tech info: Since we are moving into the EFI world, here are some basics that all should know.

Closed loop operations - engine operations in which AFR(fueling) is controlled and constantly maintained thru feedback from the O2 sensor. Closed loop functionality usually is from off idle to somewhere around 40% throttle and/or loadings.. This function is used/needed to pass EPA testing and certification - and the closed loop AFR target is usually set at 14.7:1

Open loop operations - Performance operation fueling. O2 sensors are not used. Fueling is by internal "tables" that model airflow thru the engine and provide information to the ECM, at all moments in time, as to how long to keep the injector open for the pre-programmed AFR targets.This is a static fueling scheme that does not change, regardless of what you bolt onto your bike. Since the EPA is NOT concerned with performance operations, the manufacturer is free to set whatever open loop AFR targets it wants. Contrary to prevailing propaganda, stock open loop AFR targets are usually quite rich with horrible "pig rich" settings used as a "fail safe" measure for high RPMs + high engine temps. Manufacturers do this because rich AFRs provide engine safety - usually, tuners REMOVE fueling from stock open loop targets to create more power thru a proper performance AFR..( "too rich" kills power just as badly as "too lean" - it just does it in a "engine safe" way..)

The 2018 KLX will need a complete dyno AFR chart of WOT (open loop) operations before we will know how much modding can be done before a tuner is required. This will be mandatory. Once stock open loop ops are determined, airflow mods can be made to increase power levels, without tuners. It is quite common for rich stock fueling, that is leaned out with airflow improvements, to become correct high performance fueling.. Airflow improvements such as headers, slipons, airbox lids being misplaced in the attic, ect ect.. may ALL be allowable if the stock fueling is rich enough..

Retaining the O2's will allow closed loop operations to continue self adjusting the fueling to factory specs. EPA testing also involves some timed accelerations that may be into, or very close to, open loop operations - whether these accels are open loop or still closed loop is determined by the parameters programmed into the ECM - specifically, how high-up in the RPM and Loadings/throttle position range are closed loop ops designed to operate in..

When you duct tape an EJK or PCV to your bike - you deactivate closed loop fueling. The device will take control of ALL fueling ops based on its' programming - you will not get the advantage of instant temperature, altitude,(etc) compensation of the closed loop functionality.. Your MPG will also be controlled by the tuner..


Not knocking the current piggyback tuners - advanced flash tuners are not available at this time - just providing information..

Turns out to be a simple equation - get the bung and be ready now, and forever, with whatever tuner you want now, and whatever tuner becomes available in the future.. Flash tuners, when/if they become available, will require the bung and offer total control of EFI. DJ auto tune will require at least one bung.

Don't get the bung and you are stuck with the loss of closed loop ops, you are at the mercy of your local dyno shop for dialing in the PCV fueling curve, and will not be able to make use of DJ's auto tune or any future Flash tuner.. This means you will likely end up purchasing both headers, the wrong one now and the right one later..

Someone, ASAP, needs to get a new KLX on a dyno and at "full hot", operating temp, get an AFR chart. With that, I / we can begin the process of creating and advising on performance mod combos - hopefully without the need of a tuner..

P.S. The above posts are only intended to create the beginnings of competency with this very complicated subject - and presented in an overly simplified manner.. Anyone that wants "nuts and bolts" / details, just ask..

What about a will\can it work with the 351 kit?

About the 351 or ANY significant increase in power potential: A fuel injector has a "performance envelope" of operation that it will perform correctly within - outside that, it does not. Overlook or ignore this, and you risk much.
WIthout getting too technical - armed with the tech specs of the stock injector and the KLX fuel pressure spec , its' ability to support higher power levels is a simple calculation - with a myriad of online injector calculators.. If the stock injector will not support 26 -28 hp , a different injector must be used..

A PC5 or EJK , once programmed to run the bike, may be pushing the stock injector past 80% duty cycle. As I stated in another thread, duty cycle is a measure of how hard you are working your injector. This is also calc'd with online calculators.. As a rule , 80% max duty cycle is ok, going over that is increasingly bad.. As DC rises past 80%, high RPM fueling begins to falter as the injector cannot deliver the requested "squirt volume" in the amount of time it has available to do so.. To be melodramatic of the possible scenario - This is where you are oblivious to the fact that your 351 is being slowly destroyed every time you run it past a certain RPM and why you have to carry a spare injector in your tool kit..

A complete Dyno test ( With AFR charting) of your bike will reveal any injector related problems that affect fueling.. WIth a properly sized injector, and properly tuned , the WOT AFR chart should be a straight line somewhere between 12.8:1 and 13.0:1

There is another option. Get whatever system you want (new or used) and install a 12mm bung for the O2 sensor (In the exact, correct, stock location) . This is a simple and quick "mod" - have it welded on at a muffler shop..

I own both, (stock header+loud slipon) AND complete FMF systems - and I've run them both, fully" dyno tuned in", running lidless, on my KLX..

They are both fun - but with significant differences in power cures - so much so that the capabilities of the bike and the way you ride it will change.

Choosing a slipon that kills any chance of adding a larger dia. performance header in the future is not optimal. For instance, Full FMF with Megabomb, lidless, tuned in, and the KLX will cruise at 80mph (if your speed limits go this high, as they do in Texas, this could be very important..) with a top speed of 100 plus !

On the other hand, FMF slipon with stock header (lidless and tuned in) will loft the front tire over obstacles far "easier" ( 1st gear only) while loafing along a trail off-road..( Full system will do this too, IF you are riding "aggressively" at high RPMs.)