Update:

Second Update: I've officially killed my catalytic converter on the FM downpipe. Wewt. Tomorrow I get to replace it. -_-

What's the best method of rev limiting, anyway?
I'm thinking fuel cut would protect the cat and turbo from backfires but leave the engine prone to detonation, while spark cut would do the opposite.

Pretty much what you said.:dealwithit:

From what I understand, spark cut is generally safer. but yea, it kills cats.

So I'm pretty much decided I'm just going to keep this thread going so others can learn off my experience.


I'm starting to address things like A/C. Can anyone point me in the right direction to where I can sort it out? If I'm just at idle, and I turn on a/c, it comes on fine. Or if I'm driving at a steady pace. It's only when I have the a/c on and I come to a stop at like a red light or something, does my idle freak out and sit at 3k rpms and slowly lower, or sometimes it'll rev itself up too 1500, then 2000, then back down to normal. Or while driving I can take my foot off the gas and since idle is so high, it will steady drive itself at like 15-20mph.

Here's my a/c settings, anything seem out of place?

https://www.miataturbo.net/attachmen...ine=1374436172

https://www.miataturbo.net/attachmen...ine=1374436172

Great thread with great info. Jumping into this MS stuff with as much knowledge as you had in the first posts :)

Good luck with perfecting the tune!

Ok I am still afraid to play with timing. What are some things I need to know when adjusting the ignition table? Obviously from what I learned first thing in this thread is what an ALL OF IT table looks like and what a conservative one looks like. Is there anything I need to be aware of before I start tweaking? I'm going to be conservative as heck about it. Seems like common practice is just add timing till knock then dial it back slightly. This sounds like the wrong way of doing it to me so I just wanna cover my bases.

Here's a quick update. Been learning as I go. Laptop died and I had to do some last minute tuning before the dyno.

Stock turbo @~11-12psi with pegged 10.5 afr and conservative timing.

I should be proud, first miata ever to make more torque then hp. Overall I'm happy, not too bad for literally just doing the basic's for tuning the megasquirt. I'm confident the more I learn I'll be able to extract more out of it. Gonna let Dan and my other buddy take a look at the logs etc and see where to go from there. Come spring It should be a lot better.

Attachment 239459

Whats your rev limiter settings (how much retard, soft cut, hard cut) on that video?

Say again?

Post up your MSQ. As for the idle AC issue, you've likely got Closed loop idle set to use the "last known good value" so while you're cruising and the AC activates it ramps up Idle PWM, so when you stop Idle PWM is at a goofy value, like 62, when it should something closer to 35. MS recognizes that the idle is higher than the target and it slowly ramps back down. Setting Idle to use the Look Up table will eliminate this issue. You could probably use quite a bit of timing tweaking if you're still on the IHI (stock) MSM turbo, it should be spooling quite a bit faster, or your wastegate is possibly cracking early.

This is my old motor with a 2871. The VVT on the old motor had leaky O-rings, so it didn't work nearly as well as my new motor. But, as you can see I'm spooling by around 4200 or so. THis pull was in 4th gear as well, on a six speed car. I'm running 15-17 psi now and still spooling around 4200 or so since the VVT is working better. Good news is, you have tons of room for improvement, and your car is going to keep getting faster and faster.