Megasquirt (and EFI in general)

MXM

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I posted this in "Jag Series III megasquirt" thread yesterday, but now I think this deserves a separate thread.

We're in the process of planning a K-jet to EFI conversion for friend's Ford V6 (Cologne, 2.8). Spectre's thread has a lot of info, but there are a few things I can't figure out yet.

What we have already: EFI intake with two throttle bodies (left/right bank), 6 hi-z injectors, common rail with FPR, idle control valve, wideband O2 with a controller, TPS. No ignition parts yet and no air flow metering.

1. Batch-fired or sequential or semi-sequential injection?

I understand most older EFI systems are batch-fired. Without a cam sensor the injectors can also be fired in pairs (semi-sequential), kinda like wasted spark. Is batch-firing "outdated" now? The general idea seems to be that sequential gives better idle, and at high RPM it doesn't matter. How much of an issue is this? Without a cam sensor full sequential isn't possible, but crank-timed semi-sequential is. The problem is that Megasquirt II has only 2 channels, so for 6-cyl we can only fire all 6 at once (3+3 makes no sense I think). For semi-sequential (2+2+2) a much more expensive MSIIIX is needed. Also, how are injectors timed in a batch-fired system? Once per revolution or several small squirts?

2. Air flow metering

From the beginning I was planning on MAF as he most "advanced" method, and really thought it's a no-brainer these days. But Spectre mentioned in his thread that MAFs are difficult to get working on MSII. And I find a lot of discussions online how great the megasquirt is because it allows you to remove factory MAF :? Technically all MS versions seem to support it. To get the MAF working we need to combine two TB inputs into one hose and put some aftermarket MAF there (any suggestions which one will be the easiest for MS?). And if not, how to calibrate the system for metering with MAP, is there a fixed table to make temperature correction, or is this going to be engine-specific?

3. Ignition

EDIS6 and a coilpack seems an obvious choice. Are there any benefits from driving the coilpack (or individual coils) by MS directly? EDIS needs a crank sensor, can this sensor be used for both EDIS and MS? Or can MS operate fine with just a PIP signal from EDIS and is able to synchronize the injection correctly?

4. Microsquirt/MSII/MSIII?

We're quite tempted by the Microsquirt, which is basically MSII in a small sealed package, without in-built MAP. Also cheaper.The car in question is an offroader, so having the box watertight is a bonus (good idle and low-torque is important for the same reason). Microsquirt also can't control 6 individual coils, but with EDIS6 this is no issue. Basically, I just want a confirmation that Microsquirt is enough for this application, and we're not missing something important by not getting full MSII or MSIII :)

5. Tuning

How hard will this be to get running decently without a dyno? Can we use a generic map and then use the wideband lambda reading for some basic adjustment? Not looking for a peak power now (and right now the engine runs just awfully with this old, worn, badly set-up k-jet anyway).
 
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Electric-Mayhem

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I'm running a Megasquirt system on my Toyota, but I wussed out and got a plug and play system with a base map for it already. I can offer a bit of advice, but I would encourage you to go to the Megasquirt forums and ask these questions if you haven't already. Check it out here... http://www.msefi.com/index.php

I'm still learning this stuff too, so I can't claim that all of this is 100% correct but it might get you started...

I know my Toyota is batch fired, but its a 20+ year old engine design and the wiring is all interconnected from the factory so I'd have to redo the wiring to get it do anything but batch fire and the benefits didn't seem worth it to me. I know it runs fine with batch fire and I seem to get decent mileage(MUCH better then the stock system), but it would also be cool to individually fire them at the optimal time too. I wouldn't call it out of date, but I wouldn't call it ideal either. Its certainly good enough and will better then a carb for sure.

The MSII and MSIII systems(but not the Microsquirt) all have a MAP sensor built into the board as I recall and it allows you to simplify things a lot since all you need is a vacuum line off the intake manifold. To me, this seems the best since a lot of the work of getting the sensor to work is already done. Using the MAP sensor uses the "Speed Density" type of air flow metering, so look that up. This page... http://www.msextra.com/doc/ms3/fuelcalc.html ... is a good resource for figuring out your airflow and making corrections in the software to accomodate. Warning, its pretty math/technical heavy.

The EDIS system is very popular with the MS crowd and its fully capable of controlling it without a control module I believe. To me, this seems like the way to go since it will allow you to base ignition off of AFR and other engine parameters and allow it to control things on the fly. I don't think the wiring is any more then a few wires, so it seems like a no brainer to me to let MS do the thinking for you. You'll have to provide the trigger wheel+sensor input for it though. Adding that will take some small fab skills, but it doesn't seem to complicated. If you really want it to be standalone, I'm pretty sure the MS system can do it that way too.

The Microsquirt system cuts a lot of stuff out to fit in the space, so its up to you on whether you want to use it. You can do external sensor, fuel, and ignition modules, but to me it seems nice to have it all in one box together. MSII vs MSII seems like the main difference is whether you want fully sequential fuel tuning or not, and the more modern connections (USB/SD Card instead of Serial). It looks like you can do a daughter board or external module to do 6 injector semi-sequential with the MS2, but its up to you. Here is a detailed comparison between all the MS versions... http://www.msextra.com/feature-xref.html

There seems to be a lot of info out there on getting started with the map creation, if there isn't someone who hasn't created one already. The cool thing is that once you get it going, with your wide band O2 sensor, the MS system can auto-tune to parameters you set and make adjustments based off the AFR and other sensor readouts and it will constantly be learning and adjusting. I've never made a base map, but while I won't say its simple its also accesible. You'll definitely have at least a bit of a learning curve with it, since there are a lot of different things to worry about (I still get overwhelmed sometimes with mine).
 

MXM

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Thanks, Electric-Mayhem. I was away, so it took me a while to finally read your message.

After some deliberation we decided on MSII with extra board. Also not going to do MAF for now, will start with MAP and see how that works. Probably wont use EDIS module, but control coilpacks directly with the MS, as the extra board allows that. That also means we can sync injection to crank (can't do with EDIS). It's gonna be batch injection for now, but really want to experiment with semi-sequential once everything is running.
 

Electric-Mayhem

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Sounds like you have a plan and it sounds like a good one. I think that is essentially what DIYAutoTunes DIYPNP is, which is what I'm running. Seems to work well, and it adjusts timing and all of that using the Toyota system. Batch fire seems to work fine with mine, so no plans to go sequential or anything.

Good luck and keep us posted on how this goes.
 
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