Does anyone know if the ECM connector for the on-road KLX 300 models is the same as the EFI 250? I've been doing some research, looks like the 250's ECM side connector might be a JST WPZ, specifically an S36B-WPZK-A. Hopefully someone can share a picture of the 300's ECM for reference. I've included some screenshots of the WPZ datasheet:



Why do I ask? I've got a 2022 KLX300 on order, and instead of buying a piggyback fuel controller I've decided I'd rather design my own speeduino-compatible ECM and have it plug in to the original wiring harness. That way, I'd have full control of both ignition and fuel maps, and wouldn't need to worry too much about the secondary throttle causing issues- it could be locked in the full open position. The designs and firmware are open source and I plan on posting updates to GitHub or something in the future.

Getting a PCB manufactured is pretty cheap too, last time I did something like this it was $10 for 5 (plus shipping) and I had the boards at my door in a few days. Ideally I'd like to have a PCB ready to test when the bike arrives, but the problem with these WPZ connectors is that they aren't listed at common distributors like Digikey or mouser, so I'm going to have to contact them to see if a special order is possible. the earlier the better

 

Quick shot of KLX300 ecu. Don't know if it helps.
Ambitious, cool project. Good luck. Well beyond my current skill set.
One challenge may be the ignition, or maybe you already have that covered. All of the CDI circuitry is in the ecu.
What would be cool to start is being able to just get the diagnostic link to readout, and maybe figuring out how to flash the stock ecu. Just a suggestion that you may be capable of based on the project you are considering.

 

Thanks a bunch, that looks like the exact same connector. We will see if Digikey responds to my special order request...

Yep, the ignition module is something I'll need to do some more investigation on. Last project I worked on (supermileage car in university) had an external ECM-triggered CDI, so it wasn't a concern. GM smart coils are pretty cheap in my neck of the woods, so I might use one of those in the mean time.

 

Keep us posted, look forward to following.

 

So I've got a small update. Spoke to Digikey, and JST America has a minimum order of 192 for the connectors, and the lead time is 26 weeks. No way I'm going to spend $2000 on an entire case of connectors only to receive them in August.

Luckily, JST Japan has a web store, and the minimum order is 10- submitted an inquiry, and it's only a 6 day lead time and shipping is free. Fedex shipping too, so it shouldn't take too long to arrive. It ended up being about $150 after the USD->CAD conversion. I haven't decided what I'm going to do with a bunch of extra connectors- perhaps I'll try making an adapter for a MicroSquirt, apparently they have the ability to use the MAP sensor to detect engine phase for fully sequential engine operation.

On the PCB side of things I did make a silly mistake- I created the design before I had the processor board in hand and the footprint on my PCB is exactly 2.54mm too wide. I left the Vin pins at the top of the footprint on purpose, since those are only used for providing unregulated power, and the PCB will already have a built in 5V power supply for the processors, sensor driver, and sensors.



The bike itself is still a ways away, so I'll have time to improve the design and catch mistakes before having the next design manufactured. Apparently the dealer doesn't even know when the bike is supposed to arrive, something to do with supply chain issues I guess...

 

Wow... all of this is totally beyond me!
However I can help with the secondary throttle issue. I just removed mine yesterday. Took a long time to dig down to the plate. If you try, make damn sure you use a driver that precisely grips the tiny screw, as it takes a fair amount of force to loosen it without stripping.



Haven't ridden it yet, but just revving the engine is more responive to throttle input. I'll be riding a lot today and will report on the results.

 

Good to know

Hopefully I don't need to remove the secondary throttle plate though, my plan is to "abuse" the stepper idle control built in to the speeduino firmware. It has an open loop mode where I can specify how far to open the valve depending on the air temp, in this case I can set set every cell to 100%. Funny enough, I was looking through the service manual and the off-road KLX 300 does have a stepper controlled IAC valve, while the on-road model is stuck with a manual adjustment and the throttle plate.

 

Rode it more today with no secondary plate and really like the snappier throttle response.

I understand that this is totally subjective, but it feels like the engine requires less throttle input to run at a certain speed and rpm. It may just be from the quicker, livlier, more immediate response to throttle input rather than the absolute throttle position itself. Regardless of which it is, this is a simple harmless reversable mod I highly recommend.

 

Does anyone know the color code of the wire on the ECM connector for the "rpm signal"? I need to tie into it to hook up a gear indicator.

 

Hey, there's an rpm signal wire on the diagnostics plug.





White: + 12 Volt
Black/Yellow: - Ground
Green: Data