Mazda B2200 Carb to EFI

[JG-2200]

Hi all. New to this forum, and very new to the whole megasquirt thing. We started with a carbed 2.2 B2200 engine. We originally wanted to convert to efi because carb was running poorly and we liked the idea of efi much more. We decided to go with the megasquirt because the tuning.

Anyways, here I am. Megasquirt II assembled, relay board inside the engine bay. We've wired for controlling the hall/optical sensor on the distributor, but never got any RPM signal. We verified the rpm assembly is working on the board through the testing. We've tried alot of little troubleshooting through different wiring and different settings in the megatune. We decided to move on and try triggering from the coil instead, and we put the carbed vacuum advance distributor back on. It's reading RPM now with that way, but we'd eventually like to control ignition.

Any ideas?

Also, what's a good way to get started on tuning the fuel only? It won't idle, and it's having some misfiring. Also seems to be reading pretty lean at low rpm's.

[Matt Cramer]

I'd trigger from the coil for now. Fuel control is going to require locking out the distributor advance mechanism. How many wires does the distributor sensor have?

For fuel tuning, I think you may have answered your own question: "It seems to be reading lean at low RPMs."

[JG-2200]

We've got the advance mechanism hooked up. It's just a vacuum line we attached to the intake manifold.

The EFI distributor has 4 pins. 1 of which doesn't need to be used and then there's a 12v, signal, and ground.

[Matt Cramer]

Are those on the sensor or the module?

Don't forget the centrifugal advance.

[JG-2200]

It's a plug on the side of the distributor. It's the stock EFI distributor we want to figure out.

We're using the carb one right now and just controlling fuel, not ignition.

[Matt Cramer]

Ok. I'd check to see if there's a four tooth wheel inside the EFI distributor; Mazda tended to either use this or (at least on the turbo version of this motor) a combination of a 24 tooth wheel and a 1 tooth wheel. Let me know what you find.

[JG-2200]

Yes, there is a four "tooth" wheel. I've been running fuel only for awhile now but I'm still looking to get some spark going as I believe there's some extra power to be and better drivability.

Also, is there a big difference between the Ms1 extra VE table values and the ms2 extra ve table values? I know someone else who did a megasquirt but ran a ms1 extra and I'm trying to use his ve tables as a reference but the values seem alot lower and also seem to be based off kPa not throttle %

[Matt Cramer]

This should be pretty straightforward to set up then - no wheel decoding needed or anything.

MS1 and MS2 do have slightly different fueling equations for speed density, and very different ones for alpha-N.

[JG-2200]

We wired up the megasquirt for a hall/optical sensor and never got any rpm from the dizzy, so we're not sure what to do. We figure we might wire up the ms for the VR sensor and try to use that...

[Matt Cramer]

How many wires does the sensor have?

[JG-2200]

Four, but I've been told only the top three are needed by someone else who has done this. Signal, 12v power, and the ground.

[Matt Cramer]

Ok, I think that one would use Hall / Optical input but needs a 12 volt pull up as well.

[JG-2200]

the ms2 board is already built for the hall/optical, and we had the dizzy all wired up with 12v power. our issue at the time was getting no rpm signal

[Matt Cramer]

Right. I think you need a pull up resistor. That is, put a 1K resistor between the 12 volt and the signal wires.

[JG-2200]

alright, i'll try to locate an electronics place nearby and pick up some resistors. i'll let you know when we get the chance to fool around with the efi dizzy.

[JG-2200]

just wanted to confirm something now that I have the resistors.

i have the ms2 latest board from DIYAutoTune, i built it for the hall/optical sensor per my dizzy. i thought i read in there that with this board I don't need a resistor for this model? could be wrong. if so, where does it need to be..?

[Matt Cramer]

You do need a resistor. Run it from TachSelect to S12.

[JG-2200]

I put a resistor in the proto area, and ran a wire from one end of the lead to tach select and the other end of the lead to S12. Changed the settings to basic trigger and spun the dizzy with a drill - didn't get any rpm again.

the board has the hall/optical and vr setup but it's jumpered for the hall/optical settings.

we know the dizzy is giving off voltage as we read it with a voltage meter under the 200mv setting and got a reading that seemed accurate according to how fast we spun it.

we also tried putting a resistor in the 12v power line as well but that also didnt change anything.

[JG-2200]

tomorrow we're going to wire it up for VR and use the carb coil (we think it's a vr) and see if we can get somewhere with that.

the truck ran fine on just fuel only but it would be real nice to get control of advance as well.

[JG-2200]

couldn't get any rpm with VR either. gah, what the heck is going on here