Knurled wrote:
Swank Force One wrote:
Knurled wrote:
cghstang wrote:
Is 95.6% kind of high for injector duty cycle?
You don't wanna know what teh RX-7 runs them at then (:)
But then, I'm not running a piston engine which can melt pistons/valves if they run lean under heavy power, or a turbo engine which gets even more expensive when that happens... or worse, a piston engine with a turbo on it.
I'm fairly certain the MSM runs them well over 100% as well.
I KNOW the MX6 does. Ever seen another 4 cylinder make 270whp+ on 330s? E36 M3's ridiculous.
300+ crank horsepower on four 330s is not ridiculous, it's impossible, unless you're running in the range of 70-80psi fuel pressure over manifold pressure.
Anything over 100% duty cycle just means the computer wants to open the injectors before it wanted to shut them, and it's just an academic number.
For example, my injectors go static somewhere in the mid-8000s. The air/fuel mixture goes too lean to ignite at about 9500, so it's a dandy rev limiter...
http://www.performanceprobe.com/forum/showpost.php?p=515968&postcount=98
Swank Force One wrote:
http://www.performanceprobe.com/forum/showpost.php?p=515968&postcount=98
55psi only brings 330cc injectors up to about 370cc/min "normalized". (Ignore max pressure. That 70psi has 15psi of manifold pressure fighting it, so the pressure across the injector is still 55psi)
Four 370s at static is still only 260 crank HP worth of fuel. Either the injectors aren't stock, or the engine has better BSFC than your average diesel engine, or the dyno is a wee biut optimistic No, that never happens...
The thing is... this isn't uncommon. And happens on all kinds of dynos.
The long and short of it is, that boost pressure on that turbo gives about that much power on an f2. If the afrs are safe it doesn't matter what injectors they are concerning the validity of the numbers.
These engines are wierd. Real wierd. I've seen over 300whp made on a similar setup similar turbo on 22psi using 370cc injectors. Which comes with almost 400wtq. You won't come near these numbers using the same injectors on megasquirt.
Look at dansxr2's mx3. I had that thing running 15psi at the challenge on stock fuel, still pig rich. He switched to megasquirt and the injectors hit 100% duty cycle by 8psi.
The engine pretty much IS a diesel if that means anything.
So how does Evan fix the issue with his turbo BP miata? 
Tests his spark plug wires and coils. The injectors aren't the immediate problem.
Rupert
Reader
4/20/13 10:20 a.m.
Evan B,
From these postings I assume you are into modification rather than "pure" restoration.
Have Fun! It looks like it's going to be great!
Another thing I just remembered. When I first swapped the engine and turned the ignition on (before cranking it) there was a loud pop and smoke from the area of the CAS. I shut it off and investigated but didn't see any burnt wires or anything. After that it never happened again and it ran fine so I forgot about it.
Not sure if that has anything to do with my problems or not.
The one thing I learned at school related to electronics was to never let the smoke out.
Perhaps I just need to buy some replacement smoke.
I wouldn't see how a short in the CAS would cause it to miss only under hard acceleration. I could quite possibly be wrong though.
My long term plans include MS3 and more modern sensors to replace the CAS.
http://www.youtube.com/watch?v=7G6wnoUPn3g
Photos by Jason Massey
The miata was driven to 1st in MR and 2nd or (and technically) 3rd as well. The cutting-out issue persists.
You guys had an event over the weekend? lucky
You coulda come down... registration's only $35 too!
Now I want a Miata with zero offset wheels and Stratos-style flares.
I want that as well...along with some more suspension travel.
The project this weekend is to make ducting for the radiator so the air goes through it rather than around.
And I figured I should clean out the fenders while I was at it.
Fender liners? I still get dirt packed into strange places, but not THAT much. Having fun is fun, and that looks like fun, as usual.
It has fender liners but there are some gaps. That is a very common place for dirt to collect on Miatas.
Did you figure out your Megasquirt issue? I'm just seeing this for the first time and can tell you that you definitely need to make some changes if your injector duty cycle is going over 85% or so. At that point, the computer cannot properly control the injector because it is so close to being open 100% of the time. Basically, the computer will start trying to open the injector while it is still closing. Anything over 100% duty cycle and it's flat out impossible to get more fuel through the injectors.
To remedy this, you can try lowering the number of injector pulses per cycle, which is a setting in megasquirt (this will only get you a little more room before maxing the duty-cycle though and you need a lot more). So, you'll need to boost your fuel pressure or put in bigger injectors, but you definitely need to change one of those things.
Haven't solved that issue yet. Larger injectors and a pressure regulator are definitely in the works.
