Megasquirt Saturn

[TireSmoker]

I'm surprised I haven't mentioned this car yet, but last fall, Andy arrived at my house with a 1995 Saturn that was picked up as a parts car for Mostmint Racing. Unfortunately, it was shortly after the Blazer project was started, so it immediately took a back seat. And that project lingered on much longer than it should've.

In the mean time, I found a good deal on a used MS2 3.57 box. This is essentially the same thing I use in the Chevelle. I bought a 12' wiring harness / wire bundle that has the Megasquirt adapter on one end, and just bare wire on the end. I'm cutting/splicing/soldering connectors as needed. It's a complete standalone harness that once it passes proof of concept will get transferred over to the racecar.

Today, I drilled a 2" hole in the passenger floor board. I fed the wire bundle down through the hole and up into the engine compartment and started laying out the wires where I want them to go. I got the injector harness done, the main ground, the tach signal from the Saturn ignition-control-module. I was able to temporarily jump power to it, I cranked the engine over and the Megasquirt registered cranking RPM. Woo hoo! That's an important hurdle crossed.

Despite having the car for a year, and having it up on the lift before, I never noticed the two (!!) holes in the transmission. Andy had told me there was a clutch or driveline issue that might need attention before trying to drive this on the street, but didn't think it was this bad..

-Dave

[Fred32v]

Ho hum, just another hole. But, the picture of your wiring harness looks like a sweet start.
When you have a chance, more pictures and maybe a starting video. Grins.

[TireSmoker]

Made a bunch more progress on the Saturn tonight. I have the injectors, tps, coolant, iac all wired. Ignition is wired. I've gotten pretty good at soldering again.

I have a small fuse panel with a main power relay and a fuel pump relay. It needs 5 connections:

BAT +12V
Switched +12v
GND (just for the main relay)
Fuel Pump +12v (which I will just run over to the car's existing fuel pump relay sockets pin 30.
Fuel pump control wire from MS (MS provides the relay low-side ground, fuel pump relay pin 85)

Andy, since I have that hole in the trans, my current plan is just to make sure I can do a basic start/idle/rev, at which point I'll just bring it and install it. Once we get your WBO2 hooked up to MS, we can dial in a basic tune real quick.

-Dave

[MostMint]

Sweet. Keep going. Two holes ? yikes.

I am going to put together a list of things I want to understand with the Megasquirt setup. For starters

1) Can we set the rev limiter at 6700 RPMs?
2) Can we get a working knock sensor?
3) Targeting optimal AFR around 12.5:1 at WOT. I know you can control this - is that in your baseline tune?
4) How are you setting up the timing advance for baseline - is it similar to stock?
5) Would like to use the Saturn ignition control module and feed it a signal from Megasquirt - is this how you set it up?
6) How are we handling the tachometer for the driver?
7) How are we going to tell if there is something minor wrong - like does the MS capture its own trouble codes and give us a way to do a check engine light?
Since the coolant sensor for the engine and gauge are separate I assume the temp gauge will still work?
9) What does it do if it loses the signal from the O2, coolant, knock, throttle position and/or inlet air temp sensors - does it have a default or safe mode or does it shut off? I assume crank position sensor is probably a shut off situation for stock ECU so we have to run that risk.

I'm thinking that trans should be good for a few short regular drives up and down the street like 25mph ish.

[TireSmoker]

Sweet. Keep going. Two holes ? yikes.

I am going to put together a list of things I want to understand with the Megasquirt setup. For starters

1) Can we set the rev limiter at 6700 RPMs? YES
2) Can we get a working knock sensor? Probably.
3) Targeting optimal AFR around 12.5:1 at WOT. I know you can control this - is that in your baseline tune? We can put whatever we want in there. Trivial to change.
4) How are you setting up the timing advance for baseline - is it similar to stock? YES
5) Would like to use the Saturn ignition control module and feed it a signal from Megasquirt - is this how you set it up? YES
6) How are we handling the tachometer for the driver? Good point. MS can be configured to drive a convential tach, although I think there is also a spare tach-out output on the Saturn Ignition Control Module (ICM) I'd prefer to use the ignition module, given a choice.
7) How are we going to tell if there is something minor wrong - like does the MS capture its own trouble codes and give us a way to do a check engine light? There are no trouble codes. However, a tablet could be mounted on the dash with full dashboard. You'd see from the gauges if something was wrong.
Since the coolant sensor for the engine and gauge are separate I assume the temp gauge will still work? That's my hope
9) What does it do if it loses the signal from the O2, coolant, knock, throttle position and/or inlet air temp sensors - does it have a default or safe mode or does it shut off? I assume crank position sensor is probably a shut off situation for stock ECU so we have to run that risk. It will just run with whatever bad data its getting from the faulty sensor, however that ends up degrading performance. With something like an O2 sensor, you can adjust how much authority the O2 sensor has to adjust the mixture, so even with bad data it can only be affected to a certain degree.

I'm thinking that trans should be good for a few short regular drives up and down the street like 25mph ish.

So, I got it started up!



-Dave

[MostMint]

This past weekend the race car made a voyage to Tiresmoke central to get the megasquirt treatment.

Turns out the car had a bad transmission - what appears to be a loose differential pin. It still enabled Dave to learn a lot and get the car running on the Megasquirt.

The mule car is in my garage now for the inevitable disassembly into parts:

It has a good engine, all the body panels, gas tank and several other good parts. If all goes to plan the seats will have a new home also.

[TireSmoker]

Made a ton of progress getting the Megasquirt into the race car. The engine side of the harness is all in place, access hole cut in the floor, the box temporarily mounted, but in basic final location. I need to wire up the power, ground, connect to the wideband sensor, fuel pump, and the knock module/sensor.

-Dave

[MostMint]

Looks good. All I know is if I ever post video the world will know we are running Megasquirt! Wonder if we can get some sponsor money from the maker of that unit lol

[TireSmoker]

Progress continues. I got the main power from the Master Safety Switch. By wiring in there, I'm essentially hooked to the battery, and power will get killed when the switch is off. I hooked up a ground busbar directly to the battery. I mounted the fuse panel.

I'm waiting for a second busbar for the positive side to arrive. Once that is done, it shouldn't take long to finish.

Still need to hook up the WB02 to MS.
Fan control
Knock Module

My goal right now is to have it drivable by next weekend for a little testing/tuning.

-Dave

[MostMint]

Nice progress. Let us hope the snow stays away next weekend. If it does have to go out in the salt we'll need to clean it good.

[TireSmoker]

It runs!

I'm still waiting to get a couple pieces, but I was able to connect enough stuff together to make it start. Started right up, no issues! I've been wanting to do this for a long time, so this was pretty satisfying.

Things to do:

fan control
Configure yellow output on WB gauge for Megasquirt
Find wire for factory tach -- wire to module or MS?
Configure MS for knock-sensor input
Mount/Wire knock sensor module

-Dave

[TireSmoker]

Successful first test drive!

I first started it in the garage and raised the front wheels off the ground. I was able to put it in 4th and just apply a little throttle and brake to let it do a little bit of learning. After this, I set it down and took it for the first drive around the block. After that I got a little more adventurous and went up Wilson Mills, 306, Mulberry, East Hill and back home. I have one small issue to work out where it wants to stall when coming to stop and clutching in. Just a tuning issue, I've seen others post about it. Other than that, just fine tuning to be done.

Other than the minor issue, I'm pretty confident I could drive it back to MostMint central at this point. Not saying it's perfect, but certainly drivable.

updated to-do list:
Fan control
tachometer
knock module
find a source for switched power that works with ign key instead of master switch

[TireSmoker]

So, I guess I'm due for a little update here. I got the tach working. There was an extra wire on the IgnCtrlModule.

I have all the external wiring completed for the knock sensor. I still have to build a small circuit board for inside the case.
http://www.msextra.com/doc/pdf/html/MS2 ... .4-35.html

Also, using the original GM map sensor would require me de-soldering the on-board sensor and soldering wire leads in there, eventually running up to the engine. I really don't want to do that for a variety of reasons. I'll take any advice on making the vacuum hose connection on the intake more robust. It's a little hackish, although functional.

Fan control -- As I told Andy, something is wrong with the existing factory wiring because even the manual switch on the dash is not triggering the fan. Even after re-installing some shimming-wires that Andy and I talked about, still not working. Do I just bypass the car's wiring and run a new fan relay?

switched power source -- I've probed all of the fuseblock in the car and I'm not finding a source of switched power that is also hot in *key-start* position. So the way I've been running the car is just hooking up the switched power to a battery-hot source and the MAIN power switch on the dash is how you turn the car off.

http://tunerstudio.com/index.php/downloads for the tuning software and log file viewer -- TunerStudio and MegaLogViewer (reg or HD, either), free to download/install.

-Dave

[MostMint]

I'm wondering if we could sacrifice a factory MAP sensor to make a better connection to the intake - drill a hole through the top and insert a metal tube - then epoxy the tube to the sensor. I appreciate the attempt to use factory MAP but that is something we can easily change if we need to fall back to the factory setup.

Using the kill switch to stop the engine should be OK. I am a little concerned as I have heard shutting off the car that way can be hard on the ECU. Clearly we have to do this every time we go through inspection and have not lost the ECU yet. If we go back to factory ECU will it work the same way?

We can look at that fan wiring on my next visit.

[TireSmoker]

Modifying a MAP sensor should certainly be a do-able idea.

I don't know that the turning the main power on/off does anything detrimental to the ECU. I've never heard of that. But I haven't heard of a lot of things... If we go back to factory, everything will work just as it did.

-Dave