Megasquirt info conglomeration thread! Please add your tips!

[fowljesse]

I stumbled upon some interesting info whilst researching MS, and couldn't find any MX-3 specific info, so I'll post here about it, and hope everyone else with any MS insight will, too.

One of the interesting things I found was that you can bypass the IAC by plugging certain values into the fuel map. I haven't gotten that far yet, but while thinking of a good place to put in the extra collant temp sensor, I came up with something. Although my first and last name mean "Birdkeeper" I really enjoy killing birds efficiently, without using up precious stone resources.
I went to the hardware store, and much to my surprise, found fittings that allow me to easily bypass the IAC, and put the CTS in it's place.
Here are the fittings:



They cost about $9. Here it is all hooked up:



I ran the vacuum line for mainfold pressure into a hole in the firewall, and will be routing my sensor wires through it, also. I'll put up a pic later.

Here's where I connected my manifold pressure line:



You can see it in the 2nd picture, too.
Tomorrow will be spent tediously wiring in the MS unit. I Freaking HATE tedium!
Since I don't need the air flow sensor, I'm going to put my filter right onto the TB (which I coned out), and have 6" piping for my ram air setup. She will have easy breathing!

[onlytrueromeo]

Without coolant going through the TB, will it get too hot for it to interfere w/ the TPS or anything? I guess if you're running Pheno spacers it's not a big deal anyway! You obviously left the wire unplugged for the IAC then, correct?

[fowljesse]

The coolant actually heated up the whole thing. That's why I bypassed it. There's a wax in there that expands with heat, and controld a valve that enriches the fuel mixture at startup, and leans it out, as it warms up.
I have the MS controlling enrichment, so I don't need the coolant heating up my TB.

[onlytrueromeo]

Ya I knew about the wax and whatnot as I had to have my IAC disconnected for awhile because it was screwing things up. I thought it kept it cooler when the engine got HOT (when I had my straight neck in I had my TB upside down, and bypassed the IAC because coolant lines hit the dang roof). Nice info though, that's a good place to put it!

[onlytrueromeo]

I've been reading up on programming MS to control startup in cold climates...I can't seem to figure out how to make it work without using the IAC. If you never really go below freezing (more than a few degrees), then you don't need the IAC, but for those of us in colder climates you need it. Without the IAC you lose fast idle until its warm. I'm sure theres a way to program it to do a fast idle for x minutes every time the car is started, but that is unnecessary, and sometimes I need to let the car warm up for different times depending on the temperature.

If the car were to idle 650 when its -10 out, you would have to keep your foot on the throttle to keep the car from stalling.

Many people seem to have problems with configuring the IAC to run properly

Also Jesse, you should look at the mod in probetalk or mx6.com that shows how to remove the IAC and block it off with a plate for cleaner engine bay and l33t weight savings!

[fowljesse]

That's good for people to know, if they live somewhere that cold. It's been in the high 30s, up to the 50s when I've driven the car. I don't ever expect to drive it in anything below freezing. It's too low for snow anyway It idles really well considering how I took out the MAF, opened up the K&N cone filter neck over an inch, and coned out the TB, so the smallest part of the whole intake is the butterfly itself. MOst of it is 6" dia. (from the RAI to the filter), then goes down to 4", and smoothly transitions to the TB, which as mentioned, is bored out to cone down to (I think) 64mm. I'm going to make the plate one day...
Anyway..
Another discovery I made is:
I'm going to have a seperate spark table for running 89 octane gas, to save a few more $$ on longer trips. I don't know yet if I'll need a different VE table.

[onlytrueromeo]

Why not tune to run 87 instead of 89? If you're going switchable tables, have one for 93 and one for 87 - Im assuming thats what your doing, only with 89...there are a few people on probetalk running 87 w/ no detonation, and still running decent timing.

No to jack your thread or prove your mods wrong, but increasing intake size slows velocity and increases surface area for more friction. Obviously you want to make sure the intake is big enough, but when does it get TOO big?

[fowljesse]

Why not tune to run 87 instead of 89? If you're going switchable tables, have one for 93 and one for 87 - Im assuming thats what your doing, only with 89...there are a few people on probetalk running 87 w/ no detonation, and still running decent timing.

No to jack your thread or prove your mods wrong, but increasing intake size slows velocity and increases surface area for more friction. Obviously you want to make sure the intake is big enough, but when does it get TOO big?

Ooops. I meant 87
Yes, velocity slows down. That's why I'm impressed that it idles smoothly. I have quick throttle response, and low end power, since there's relatively no restriction. It would affect volumetric efficiency in the middle RPM, but I'm not concerned about it since I have ram air. The car feels stronger than before I did all this, but wishful thinking afects the butt dyno. I know for sure it's not any weaker Another thing possibly negatively affected by "too big" of intake is the VRIS not matching anymore. I'm not concerned about this, either, since I'm going to have MS control them, too, after I do dyno runs with them all open, all closed, and with each open. Then I'll have them open where the graph lines intersect.
I know, at least that my car is faster than a newer Corvette

[fowljesse]

Another note. If you're going to go as far as getting MS, and hooking it up, get a wideband O2 setup!
The MS is much less useful with narrowband! This will increase your cost by at least 2/3, but will make it 99/100 more useful!