Joe Perez

iTrader: (8)

You still coming up to my place for beer and soldering tomorrow, or are you past that point already?

AbeFM

iTrader: (3)

I was thinking I was past it, but then I got a lunch date in Escondido. I figure if I'm all the way up there, I might as well drop by. :-)

Currently I've got the CPU installed and up and talking, I was able to flash beta 11-22 code onto it, and now I have to read the stuff Arga sent me to make sure I have the right stuff installed, figure out what a msq file is, what to do with it, etc. I also have to build the outputs and some of the inputs, and then make up a harness.

So, yeah, lots to do. A weekend's worth, if I didn't have other stuff to do.

Maybe I'll give away my link piggy as a white elephant gift at this xmass party sunday. :-P

AbeFM

iTrader: (3)

Ok everyone, here's my issues with the build:

First: Use the pul up resistors on the JimStim or your tac won't work. Though I wonder how well this will work if the sensor doesn't put out much current....

Actual issue: Does anyone know how to program the jimstim, or make it put out a 99+ miata-like pulse train?

Also, my O2 reading is weird. There's a few spots on the pot where it works, and everywhere else I get weird, jumpy, sticky values in the MegaTune program. The voltage goes up NICE and linearly with pot travel. I checked the signal, at the connector, the board, and even at the CPU pin (scarey on 0.5mm pitch parts without real tools).....

Any idea why this is so BAD?

Joe Perez

iTrader: (8)

Abe- I totally forgot about this the other night when you were over at my place, but have you done a scope capture of the actual cam and crank sensors?

Reason I ask is that I know it'd be nice for you to have a good simulated output for bench testing, and I have two ideas there.

One, we could simply ask Jim what it would take to add a new wheel output to the simulator. Like an idiot, I forgot to write down the p/n of the CPU last night so I could check to see if it's re-programmable, but it's worth an ask.

Two, if that's a no-go, I could build you a dedicated NB wheel simulator using a parallax microcontroller I've got lying around. But again, I'd need a detailed scope trace for that. (your car doesn't have variable cam timing, right?)

AbeFM

iTrader: (3)

I am pretty sure the sim is programmable, cause he tells you where to buy a USB cable for reprogramming it (though why there's some doubt that I could hack the end off a cable and attach it to the board is beyond me)...

Yeah - I wanted to get traces but never got to it. I'm sure I could get some from online... I'd be interested to see what your current meter thinks of it.

Otherwise, yeah - I suppose someone could dig up a logic analyzer, but I think I already have a NB simulator in my garage, under my hood. I can just crank the motor and see if it gives me RPM as a start.

Joe Perez

iTrader: (8)

I'm still a bit confused by that whole USB-serial thing. He mentions that it can be done, but gives no specs whatsoever on the software involved. I emailed him to get an inside opinion.

BTW- I don't think it's necessary to use the fancy current probe to measure your sensors. When I do mine, I typically just disconnect the plug and slip a piece of that 30ga wire I gave you into the female portion of the connector, then plug it back in and connect to it with a standard probe. This way I can measure 4 signals at once, to get relative timings.

The only place I've used the current probe so far was for measuring the coil primaries, to get a close look at the current profile. I wanted to reality-check the dwell times that everyone has been using, and they do indeed check out.

edit: BTW, I checked out the datasheet on the "special cable" and it's nothing more than a USB to RS232 converter, which presents itself to Windows as a virtual COM port. So you could probably just use straight RS232 and not bother with the expensive cable.

AbeFM

iTrader: (3)

Oh, I don't think I need to measure current, but I am currious - if folks are having issues reading the signal, I'd like to know what it is the ECU sees.

Guess it's time to dig into the wiring diagrams, I want to figure out what I need to take from the OEM ECU, and what I have to leave there. Ideally, the OEM only gets five or six wires to it, just enough for the AC, Alt, cruise control....

-Abe.

Joe Perez

iTrader: (8)

DOH!

I forgot you were doing a piggyback!

That means that the cam and crank sensors are still going to be attached to your stock ECU, meaning that you don't need the pullups on the MS. You could just wire the two signals directly to the base of the two transistors you threw in on the proto area and call it a day.

AbeFM

iTrader: (3)

I'm *starting* with a piggyback, and planning on extracting the OEM ecu as fast as possible. So unless the sensor can't sink the current from two pullups, I'm not worried.

Anyway, right now, there's no way the stock ECU can run my tripple sized injectors, so those lines are coming off. That leaves the ignition, which won't pull any timing so I can try to get the fuel for idle and off idle mapped, but after that, the MS will run spark too... Then I think the cam/cas/etc can all get cut off the OEM ECU

Related: Does anyone have the little 3rd '99 connector for the OEM ecu? I bought two of everything from online components, but that connector I only put in one. The part is literally 80 cents, but shipping is like $10. Sigh.