Converting MS3 Basic to run k24z3
 

Hey guys it’s literally been years since I posted. I miss this place.

I have a 96-97 ms3basic purchased 2014.

it’s currently installed in an exocet. I’m looking to swap in a Honda k24z3 and would love to keep this ECU.

the Honda uses a 60-2 crank position sensor and the cam sensors are both hall as well. It has vtec and only 1 cam has VVT.

do I need to add or remove any pull-up resistors?
Obviously 1 cam sensor will be my “home” signal (Cmp)…. But what should I wire the second one to? This would be for VVT feedback.
Do you see any obvious issues with this setup? I know these use standard firmware but I’m unsure if any of your other mods will affect this engine setup.


I’ve also sent this to reverant but I figured maybe you guys would know as well. I’ve seen a few MS k24s (mostly k24a2) but this is a bit more odd to convert a PNP ECU.

The crank is 12+1, not 60-2. You will connect the exhaust cam (which doesn't have VVT) as the main cam, and then connect the intake cam to PT4. In the VVT setup, CAM1 (main cam input) will be set to Output: Off (ie no control - it's the exhaust cam) and CAM2 will have PT4 as the input, and set the output to VVT. You will need to convert the VTEC solenoid to low side (activated by ground) as the stock configuration is high-side and the ECU doesn't have any high-side outputs.

Thanks for the quick response.

as far as crank I believe all other k series (k24a2) have the 12+1 on the front of the engine but the k24z3 has 60-2 on the rear. You can convert it but it’s cheaper to leave it. Below are haltech settings confirming this.

https://www.miataturbo.net/haltech-1...altech-103895/

I appreciate the info on vtec. I wouldn’t have caught that!!

That trigger is not supported. Your only option is to cut off two teeth from the cam sensor wheel OR if two of the three teeth happen to be exactly 180* apart, you can leave these two and cut the third one off. You can email me a pic of the cam wheel and I can advise further.

Emailed. Thanks!

Bringing this thread back. Finishing up my wiring harness and realized that I don’t know if megasquirt’s PT4 input is brought out to a pin on rev’s MS3Basic. Anyone know what pin it is on the db37 for the 96-97 version or do I need to pop it open and verify?

Should be in the papers that rev sent with your ms3.
Has all the wire colours etc etc..

I lost mine, if you still have it shoot me a pm :)

Rev replied. For me it was pin 13. Hope this helps someone.

Update on this:

I was able to get my k24z3 running yesterday on this ECU.

as I mentioned, 60-2 crank trigger. I machined the cam trigger (exhaust) so it’s a single tooth. I used 396 as my angle. I tried 36, and it would start up in batch and then quit so I knew I was out of phase.

hope this helps someone in the future. Megasquirt might not be the ideal ECU for a k24 but keeping the ECU I already have and know well saved me a lot of time and $$$.

now to get a good base tune, set up VVT, and start fine tuning!!

:party:

I am putting a K24z3 in an NB2 and running MS3x. My plan is to set the cam to "poll level" mode and not edge trigger. The exhaust cam has one big tooth on half of it (minus the little gap in the middle of it). It's my understanding that you select a crank tooth for the ecu to check if it sees and cam tooth. If it does then it knows that the cam is in the expected phase or 360 degrees off. I think I just need to select a crank tooth that will always see the exhaust wheel and not the little gap in it.

What input did you put the intake sensor on and what input did you put the exhaust sensor on?

im using the normal cam input for the exhaust cam. Intake cam is on PT4.
to be honest I am having issues with the VVT. At 0% duty I can’t reliably get it back to 0deg. At 100% duty in test mode it seems like it’s fully engaged (car won’t idle, sounds like it has a big cam) but at most reads in the 20 degree range and is inconsistent. Not sure if it’s reading correctly or if I legitimately am making those positions and have a solenoid issue. I was going to play around with solenoid frequencies and other things next weekend… but then I found out I have a messed up the kmiata slave.
**Facepalm**

How's your project going? Mine is getting wired up and I have a few questions. I'll start a new thread.

On pause due to slave cylinder issues. Turns out there was a manufacturing defect with my unit. Kmiata has helped me out and the new unit shows up tomorrow.

hopefully I can get it back up and running over the weekend. Next I need to diagnose my VVT not working right.

pm me with any specific questions.

I hope mine doesn't have the same issue.

So I'm looking for help resolving my VVT issue.

I still haven't gotten VVT working. I haven't been able to even go thru the setup for the min/max angles because my VVT2 cam angle isn't reading correctly.

Attached are screenshots and a tune and log. It just seems that VVT2 angle isn't reading correctly at all. If I put it in test mode the actuator is absolutely moving the cam, but its not registering the change on the angle read out.

When at 0% duty...the cam doesn't always register the same angle which seems odd to me. It doesn't necessarily change with RPM or anything- it just sticks at one spot.

I am using the original 4 tooth trigger wheel on the intake side. It's using PT4 as the CAM2 input. I have tried both rising and falling edge.

Is there a way to LOG PT4? Can anyone confirm there is an internal pullup on the REV MS3BASIC PT4 input? I am wondering if my cam input signal isn't working correctly.
https://mail.google.com/mail/u/1?ui=...d=ii_lker3chx0
https://mail.google.com/mail/u/1?ui=...d=ii_lker42uw1

Short answer: you should probably use datalog input PT6
Long answer:
I am probably a week away from starting my engine but I've done a lot of testing by cranking the starter motor.
Turn on noise filtering under ignition settings. High speed loggers, composite logger. Pull your fuel injector connections so you don't fire the engine. Put your exhaust sensor plug on the intake to test the sensor. Crank the engine and do a log. You should see the four even pulses.
PT4 doesn't have a pull up resistor so there will never be voltage to the signal wire of the sensor. You need to build a circuit.
http://www.msextra.com/doc/pdf/MS3XV30_Hardware-1.5.pdf
Page 208
Make it like the PT6 input on page 207
also here https://www.msextra.com/forums/viewt...ircuit#p559915
I haven't tried any of this yet but I do know that PT4 will just won't work as is.

Thanks for the response. Good idea on composite logging using the cam input. I will try that.

the reason I was asking about the pull-up is because this isn’t just a ms3, it’s revs MS3basic and he is the one that told me to use pt4. It’s what he uses on Miata VVT installs, so I was unsure if he already built a pull-up circuit internally. I may open up the unit to check for myself. Obviously no pull-up would most likely be my issue. There are a few YouTube videos of novices trying to run the k24 on megasquirt diy builds with no pull-ups on their cam or crank sensors and it causes major issues as you can imagine.

Confirmed a nice 4 pulse trigger when plugged into the cam input. Time to crack open the ECU and look into putting a pull-up on pt4.

thanks for the suggestion on how to log!

So with no prototype area on the ms3basic and no obvious jumper I decided to just do an external circuit in the harness. Worked great. Now have a proper vvt2 cam angle reading!