Morning all, I'm going to be attempting a megasquirt II installation that will be piggybacked on my gm ecu (so i don't have any check engine lights, gauges all work, etc) to control fuel and spark. i'm sick of burning chips and now that i'm installing a turbo setup, i want the added capabilities of the megasquirt to aid in tuning and logging. If any of you have gone through this I would love to hear any tips, tricks or experiences with it. i have searched the forums for about a week and havn't really seen any threads discussing it. if you did it, did you decided to use the relay board they sell or did you go through the stock relays.. any wiring issues or tuning issues, etc. pictures would also be cool. thanks all, Thunder

This doesn't answer your piggyback question, but a 730 ecm with $59 code will do the same thing and cost much less.

i had thought of that... but it basically requires i keep burning chips and doesn't have the additional capabilities and on the fly unrestricted modification potential that the ms does. with a ms, if nothing else the savings on dyno time will pay for itself as all the tuner needs to do is change a field, not stop, reburn a chip, install it, and run again.

with rt tuner and an ostrich from moates you can tune on the fly with a gm ecm. Then burn a final chip once your done.

hmm... interesting. how difficult is the conversion from a 165 to a 730? what psi will a stock gm map sensor read to?

also... does this version of ecm use a wideband?

Yes the $59 uses a wideband O2, GM 3 bar map(good for 30 psig), and is fairly strait forward to swap over. There should be a few articles on this site on how to do it.

very cool. thanks. figure that will save me a few hundred. i see you have a 749 in your sig... whats the difference between that and the 730?

Here is a good site that covers what changes are required to go from a MAF '165 ECM to the '7730 ECM:

http://www.eecis.udel.edu/~davis/z28/ecm_swap_730/

Along with a bunch of other good info...

RBob.

MS2 is definitely the way to go, im running my engine with it, and so is another hardcore car I know of. as the cheapest most versatile aftermarket efi around, no reason to pass it up. you dont need a stock ecu to make your gauges work. plus megasquirt has wideband/ dual wideband, AUTO-TUNE, a 12x12 resolution grid with adjustable tables. tps capture to set your throttle % without adjusting your tps itself. 2.5bar map standard, every ignition input is usable, go DIS if you want. both sides of the engine can be tuned individually. automatic boost controlled events such as fuel ramping or spark retarding.
I can go on, I worship the thing.

Thank you! thats excellent news to hear. do you have any pictures or pointers? I'm not well versed in tuning yet.. i've burned a bunch of chips doing minor adjustments but not anything as big as doing a new engine configuration on a brand new box. did you wire it directly or are you using the relay box they sell?

I wired mine directly, using my own relays where required. one pointer is get a wideband 02 to get that idle and driving tune down, that is critical to getting the proper cold start enrichment and ASE correct. that way you never have to fight starting it cold again and can focus where the tune really counts - going fast.
I can get pics, what would you like to see?

nothing fancy.. just how you spliced into your factory harness... injector harness, etc. also where you placed your ms. i'm a noob so trying to figure out placement and harnesses, etc

i'm going to keep my computer so my cruise still works and if something goes wrong with the ms i can swap the wires back and at least get the car started and moving.

i made my own harness, hacked out the old factory harness 100%, the group of wires coming out of the drivers side firewall leads to all functions from the interior such as gauge functions, switchs to lights, etc.. so i just re wired that as i saw fit. i drilled two holes in my firewall so icould run each side of the engines wire harness straight to the firewall, and in the cab it all runs to the passenger side, and my ms2 is bolted in stock location.
making a swapable harness is going to be hard especially since you will be going from a a maf to map ecu. you would have to switch sensors too. a ms2 is not going to fail any quicker or easier then a stock gm ecu.

+ 1 for the megasquirt. I've had mine running for two years... AEM wideband, stepper motor control, knock sensor... the whole 9. You can either splice it into the stock harness or rip yours out and make your own.



I just have my megasquirt bolted into the stock ECM location.

does the ms also have provisions to control the cruise control,tc lockup, air conditioner, etc?

i'm thinking half and half.. going to splice into the existing harness for sensors (knock, iac, cts, etc) and make one to control the injectors, wbO2 sensor and ignition as those harnesses aren't looking too pretty.

in all honesty, how hard is it (with correct wiring) to get one of these systems to start and run the car? are there sample configurations available somewhere like there are for the gm computers so i at least have something to start from?

the cruise control is separate from the ECM. AC is as well. There is an AC input to the ECM to make it kick up the idle, but it is not really needed. TC lockup I chose to do manually. I could have used an output on the MS to do it, but I would rather have that output to do other things.

It wasnt too hard to get to run. I had it running in ten minutes.

The stock tune that comes preprogramed into the MS when you load a firmware is for a corvette l98

seriously? thats freakin awesome. all i'm aiming to do is lock the waste gate open and get this running enough to drive it down to my dyno guy and have him tune it up.

what other items are you controlling with the outputs?

also, i see you have a carputer. is that connected to the squirt for realtime diagnostics or just tunes?

connected for gauges/music playing . I dont have any pics of it with the megasquirt gauges on it. Look at megatunix though... You can make some seriously awesome gauges for it. Mine runs on a seven inch touchscreen with linux.

I'm running my fan with the fidle output. The LED outputs are not equiped to deal with any relays without adding a transistor.... I have not done that so as of now they aren't really anything. This spring I will probably extend them to a panel so I can use them for notifications of various sorts.


The megadquirt has really been a great piece of hardware for me... I built it all myself, so that is a good feeling.


-Brendan