Megasquirt Piggyback

[Z26-T]

I know there are a ton of theads on megasquirt, but all the ones I read are a couple years old, so I'd like to hear what the latest and greatest opinion is on what to do.

Quick history lesson: I have a 95 Beretta with soon to be 3400/turbo/manual (currently have a 3100/4t60 but buying one with 3400/manual) built my turbo set up for the 3100, but going to use it on the 3400 instead. Should also add that in my state SES light has to be functional (comes on with bulb check then goes out) and has to pass rolling sniffer test. My plans with the bulb check is to clip the wire for the SES and spilce into another one one that comes on with the bulb check and goes out. (that's if I will have a solid SES light). Just hoping with the right tune and cat that it will pass...

Was going to just use my 255 lph pump with 10:1 FMU and stock injectors, and not use a tune because my car is OBD 1.5. But keep reading and reading and talking and talking to people... so I think i'll just bite the bullet and go tuner, asking around my 2 options are really obd2 swap with DHP or Tunerpro or megasquirt, but ive been told that megasquirt will have problems with my IP cluster. So piggy back my stock ECM with megasquirt is the best option right?

So to the reason that I made this thread. What megasquirt will be the best route to go (for the money) and for boost. I will build the board myself to save the little bit of cash to do it, and so incase something breaks later on, I can fix it myself. So what version do you guys suggest? I would like to be able to adjust spark/fuel (at least). But i remember reading on some board that with some MS you can adjust your wastegate, BOV, and have outputs for things like NOS and water injection.

Thanks for you input. Let the bashing begin

And FYI megasquirt.com is not a place to buy a megasquirt tuner...

[IsaacHayes]

It may be possible with additional sensors and sharing of some sensors for both MS and the stock ECU to work and if the fuel/spark/etc is dead on the stock ECU won't throw a code.

If I went this route (we don't have the SES looked at) I'd just keep whatever needed for the stock ECU to control my auto and possible the IAC. And let MS do the rest.

For the versions, no idea, I don't know much about MS in that regard. Anyone suggest a route to go with?

[Azrael]

I was tempted to go the megasquirt + FAST transmission controller route but I'm opting for the OBD2 swap and chipping in for an HPTuner with 5 other guys. A little cheaper that way and I trust an OEM PCM over anything I build.

Is it possible for an aftermarket ECM to completely take over the fuel injectors/ignition system without the original PCM bitching? It might not like going past it's target redline if you allow it to with MS for example.

[IsaacHayes]

MS + piggy back should work fine for controlling your trans. A guy on v6z24 did that for a 199 2.4l auto cav and worked fine. Since our trans have vacuum controlled line pressure, even less worries. A guy on v6z24.com same thread said he got his MS1 for 140 plus shipping and assembled it himself, and has spark control mod and it's working.

If you piggy back, the stock ECM isn't going to be able to cut fuel/spark if you have MS controlling that. So whatever you program MS to do, is what your engine will do. So no worries about redline/speed cut off.

[ForcedFirebird]

I'll sell my MS1 for $150 professionally assembled. V2.2 board, set up for DIS.

ou can use it to control only spark and fuel, sharing sensors. Some sensors can't be shared, but that's covered in the MegaManual.

[Azrael]

Interesting...I'll have to give MS another look.

[Azrael]

Well I was convinced. Ordered a MS2 kit. The tuning section of the Megamanual is a little intimidating though.

[IsaacHayes]

Sweet! So you're gonna piggy back and let the stock ECM shift the trans! Awesome, keep us updated! I want to do this too sometime but it will have to wait too busy right now.

[Barry]

Im intrested as well, ms seems like a very good option for us 94 and 95 guys.

[Azrael]

I'll definitely try to document my progress in another thread. So far I only have the bare minimum ordered (MS kit and a laptop).

The nice thing about piggybacking with MS over an obd2 swap is being able to avoid having to rewire the engine bay, swapping the ABS pump and evap solenoids. Plus the process is mostly reversable should it be needed.

[viper15230]

If your really intrested I can try and dig up some of my notes for wiring it up to a 3400. Ya its fairly simple and straight forward but I did write down a lot of things and it was easier for me to work with what I had then what you piece together off line especially the ignition and iac can get a tad confusing.

[Driver_10]

In order configure MS to do proper fuel calibrations it requires about 5 sensor inputs

tach signal -(which can be shared with the stock ecu in parallel)
engine coolant temp-(which must be additional, you cant share the signal
intake air temp-(same as ECT)
02 sensor-(use an innovate LC1. It comes with analog outputs: {stock ecu, wideband AFR gauge, MS)
TPS-(this signal can be split between the stockecu and megasquirt)

Remember that the stock ecu and the megasquirt must share a common ground in order to work properly.

I will say on a side-note that it only requires two more wires to be spliced on the ICU and a relay to be rigged up for the bypass in order to convert the system to full stand-alone. But if you only want to do a piggy-back, that is how you could do it.

[Azrael]

A wideband is a given. They implicitly state that you can't reliably tune anything over idle without one. The LC1 looks perfect for this though.

diyautotune.com has some crazy fast shipping as I received my kit today. I'm surprised at how small this thing is going to be too but that'll just make it easier to find a spot for it.

As for wiring I'd be interested on how you guys wired up the injectors. As in 1,3,5 and 2,4,6 or 1,2,3 and 4,5,6?

[IsaacHayes]

Batch (MPFI) fires one bank at a time. So 135, 246. IIRC.

[Z26-T]

So which kit did you actually order?