91blkvette

Can someone confirm the C3, C9 and D13 ECU pin out function names and wiring colors pls? Bentley and Chevy Thunder are not consistent when describing these three.

MrWillys

Leonard made a mistake here:
http://www.chevythunder.com/fuel%20i...ts.htm#1990-91 speed density (Corvette ecm #1227727)
But if you correlate it with this it becomes clear.
http://www.chevythunder.com/199091_c...227727_ecm.htm

91blkvette

Excellent... thanks!

ANTI VENOM

Im currently putting in an MSII in my 91. I'm curious what will and what won't work when I'm done. Please come back and tell us all how it goes.

91blkvette

If you have any questions, email Matt @ DIYAutoTune.com Sales <websales@diyautotune.com>. He's 100 times more helpful than the MS forum. Wasted a whole week thinking that something was wrong with my ECU, when it was working fine. Be advised that the instruction guides are generic and sometimes unclear. But make sure your wiring is 100% correct.

I'm now at the point I can fire this thing up...but I don't have any mufflers on my ARH piped 427. I live in one of those quiet neighborhoods..and uncorked engines clash with the serenity!

ANTI VENOM

That's good info as I've spent nearly countless hours on that site. I was running the B&G code then moved to the MS/Extra code. That's when the trouble started. Had to rewire some things and as you have said the instructions are "generic" as the MS can work with nearly any combo. Haven't fired it yet. Still working through some issues.

Mufflers???? Serenity??? Do NOW and ask for forgiveness later.

Thanks, and good luck! Anti.

91blkvette

I got it to fire..and it sounds AWESOME Sounds like a real Corvette now.

but..it isn't exactly right..Not sure if I got the timing down right given what I see in Tuner Studio. And yep..had to re-wire a few things..for one, the fuel pump needs a separate relay ( and wire from engine bay to fuel pump... ) and I'm not quite sure my cooling fans are working. I cannot get my ECT sensor to force the fan to start..

If a new sensor does not work, more wiring to get the MS3X to control that too...

BUT DID I MENTION IT SOUNDS AWESOME>>

ANTI VENOM

The hard part is over. Just some tweakin now. I'm getting closer but the weather changed and isn't making things any easier. The concrete is cold no matter what temp it is in the shop. LOL

91blkvette

AV...do you know of anyone running a Megasquirt MS3? I need a map...can't get the engine to start. I believe it's due to the cold weather messing with the ECU. I got spark... but no fire..

aDigitalPhantom

Something to remember for the fuel pump relay megasquirts switch ground, where the GM ECM/PCM switches B+.

91blkvette

Yep..found out that how one wires a MS with the GM ECU is critical. I believe the GM fuel pump needs to see a tach signal, otherwise it does not command the fuel pump to run when the engine is cranked. I could get it to fire, but not run.. When I connected a fuel pressure tester..the lightbulb came on again. I had everything run through the MS except gages and fans..and the fuel pump. But..at least I have a new fuel pump on!

Unfortunately..I had to run an external wire to the harness outside of the tank filler neck. Can't access the fp relay wiring, so..will run that switch ground internally..

ANTI VENOM

That's a fine piece of knowledge. Took me a bit to figure out why the ol' fuel pump wouldn't run. I'm using the MS to run the fuel pump and I used the 1 to 4 relay to basically reverse the polarity. I now have two relays to fail instead of one, but it was easy and the wiring was clean.

I don't know anyone running the MS3.

I left the cooling fans connected to the original ECU. Is that what you did and they aren't turning on? I don't have as much I/O as the MS3..

91blkvette

My MS3 isn't controlling the fans (yet). Have not run the engine long enough to get it up to 210, so I am assuming that the fans will still come on. My eng temp sensor isn't coming on when grounded, so I will probably connect the MS3 to control the fan to come on at 230.

Will probably try to share the needed RPM signals to the factory ECU to make it work as normal.

TurbineSurgine

I have a ms3x running on my turbo BMW and was considering putting one together for the vette.
Have you cranked the motor without fuel and logged a clean tach signal?

91blkvette

Yep...had it running several times. The problem has to do with setting fuel feed in colder weather.. Also,can't get it to idle without throttle, and it's running rich when running. Still need to verify running timing too..

Alot of tweaking to do at once...and you never know how one tweak affects another tweak