yet another megasquirt thread

[robertisaar]

is it possible/smart to run a megasquirt only for fuel and spark while boosted?
my brother is going nuts wanting to stick a turbo on a 95 3100, so i told him i would look into it for him: my plan was use a 16149396/DF code and use the PCM to control everything up until 100kpa, then have megasquirt take over from there... does this work/has it been done before?

[Guest]

I REALLY can't see that working well, if at all.

While I'm not a fan of Mega Squirt, if you are set on using it, use it to control all fuel delivery and spark control. From the lowest vacuum to the highest boost. I can't see a good way to have a switch over from one ECM to another, or better yet a reason why you would want to do something like that.

If it was me, I would use a '7730/'7749 and $59.

[IsaacHayes]

What vehicle? If a 95 3100 from the factory it's got OBD1."5" which can't be tuned unless it's the A body which has an EEPROM and tunercats have a def for that...

And if it is a 95 car obd1.5 then you'll have to go to OBDII to control the trans, or piggy back the MS and keep the stock ECM and ECT, MAP, etc so it can control the trans ok.

[robertisaar]

95 monte carlo 3100. i am upgrading my monte to obd1 with a 1614396 PCM from a 93 GP GTP. using that i'll have very in-depth tuning capability and will be able to control the trans as well.

my brother on the other hand wants to run a turbo on his 95 monte 3100. i considered the possibility of using the PCM mentioned before to control everything under 100kPa, but it sounds like a pretty bad idea according to the_raven. and question: does code 59 contol the tranny as well? that was one of the reasons i threw it off to the side because of the 4t60-e in the monte. i'm trying to justify spending the money to put in either a 282 or a F40 in mine and if my brother likes the idea, i'll put what i learned from mine to get his going(in that case code59 would be perfectly acceptable and hell i would be hard pressed to find something better, especially being obd1).

make sense now?

[Guest]

No, $59 won't control the trans.

What some people have done in similar instances including using Mega Squirt is to use the OEM PCM to control the tranny (with some shared inputs between the two ECM/PCMs), and use the other ECM to control just the engine. It's not ideal, but it works.

I would take a look at using the '427 ECM from a '93 to '95 full size pick for trans control duties, since it has been hacked and tunable, then use the Mega Squirt or prefereably a GM ECM ( ) to control all the engine functions. You would still need to share certain inputs, but this would, as long as the 4TxxE can be controlled by that ECM, full tuning control over all drivetrain functions.
I've talked to a guy local tro me that has a 4L80E running off one of those OBD1 ECMs, and it does so quite well. He thinks that it could be used to control other E trannies as well. His ECM is also untuned, and runs pretty well for what he has. Olds 455 in a early '70s Cutlass, with a custom made 4 bbl TBI.
Swapping to a non-E or manual tranny would eliminate that side of the headache though.