Megasquirt questions

[progman]

I'm still getting everything together to use megasquirt and I have some questions I hope someone can help me with.

I understand a need a GM open element IAT. Where do I put this? Cold pipe? intake? I don't believe there is a stock one.

How does the injector wiring get setup? pins 32-35 go to injectors 1-4 respectfully? so injector 1 and 2 will on on one driver and 3 and 4 on the other?

Also one more thing I'm confused about is the AIC. Ours only has two pins right? how do I use that? Or are people just using the fidle value to do cold starts?

Thank for your time.

[r34 gtr]

You can put the IAT wherever you like. TCO had his in his intercooler piping, right before the throttle body, and I have mine in the intake manifold, right after the throttle body.

1 and 3 go on one driver, and 2 and 4 go on another, so I believe. You use a common ground.

I threw my AIC in the trash. Don't have one currently, and it doesn't bother me much, being I live in the south. Check the MSII writeup for how to do this.

[beans33]

I also have my IAT on the cold pipe couple inches away from the throttle body. seems to work fine..

[r34 gtr]

Dennis, I'll be back in Huntsvegas on the 16th or 17th with my "baller-a** whip." When is a good time to come by? Give me a call or email me or whatev. Or just hit me up on here, it don't mattah.

[evildky]

the IAT should be ont he intake pipe just in front of the TB, as for the injector wiring, it's really not that important btut he theory is to wire them acording to alternating firing order

and I run no idle air control on either of my megasquirted cars, I use the fidle to fire HEI

[r34 gtr]

Want to enlighten everyone on how exactly you did it? That would be a nice addition to our MegaSquirt page....

[beans33]

yes sir

[progman]

Note that MegaSquirt® is a bank fire injection system, you connect half the injectors to the driver for one bank (pins 32/33), the other half to the other driver (34/35) [4 are shown]. See: the FAQ. You can connect them in any order. For troubleshooting ease, having each bank on a separate driver might help. However, you might want to separate them into alternates in the firing order, which some people have claimed is theoretically slightly beneficial. As an example, on V8s with bank fire systems, manufacturers typically run one bank off one driver, regardless of the firing order. The advantage of doing it that way is it makes troubleshooting easier.

[evildky]

yes MS is batch fire, and it's switchable between alternating or simultaneous bath firing

on my L28 I alternated acording to firiing order, on my VG I wired it acording to bank

[chausaster]

For the IAT I had mine placed in the intake side of my IC piping... I keep blowing it out though so thats no fun. For the injectors if your running them alternating, it goes 1 and 4 are together and 2 and 3 are together. That'll give you the right firing order. Same thing if your run MSextra code with it.

Little horror story and I hate myself for this ever since, If you try to run each ignition coil off of each ignition driver you may run into the problem of burning leads and ignition driver. I did that on mine and I haven't been able to get my MS to run since... I'm sad 2 years without a running CA.

[progman]

I have a MS harness and there are two wires; one for each bank. Do I just maek a "Y" and run the wires to 1 & 4 and then make another "Y" with the other and run to 2 &3 ?

That makes sense to me.

Also, I have more new questions!

How should I power the MS? should I use the B/R wire in the "white" plug near the fuse box on the 240sx? (labeled ignition switch)? is that the "main relay"?

"Now your main relay, I cheated and just spliced into the ignition switch harness. I spliced into the Black/White wire, but after the plug it becomes Black/Red. So you can splice into that, you can take the power wire from megasquirt and the module make it into one and splice into the Black/Red wire. You will need to eventually add a fuse and relay between those wires."

Why would I need to add a relay here? I don't understand. and add a fuse? other than the four normal fuses you would use?

Thanks so much for you help so far guys. I can't wait to start to get into the tuning.

[r34 gtr]

Don't think i have any relays, but I'll check for you this afternoon. And since its 2pm and I just got up, afternoon will probably mean 9pm tonight.

[progman]

lol,

awesome. I appreciate it. I just ordered my IAT sensor/bung etc and the rest of the plugs I needed. The only thing I have left to get is the plug for the VR sensor. The one I got was wrong. I'll probably just raid the junk yard next weekend for it. I still have to make the bracket yet but some kids down the street said they would help me.

Where did everyone mount the coils?? I need some ideas here.

Thanks everyone.

[progman]

instead of cracking the throttle plate to get the CA to idle with the megasquirt wouldn't we be much better off with this?

http://www.diyautotune.com/cat....html

Basically this is a generic IAC system. I'd like to get people's input on this. After I get things going I want to install one of these.

[slw240sx]

The Ca really doesnt mind not having a idle valve. even in 20deg weather mine starts right up and idles. i run my idle right around 1K and has never died on me or stalled.

i also run my IAT a few inches from the throttle body in the IC pipe.

for the person having theirs pop out. are you using the screw in metal bodied sensor?

[r34 gtr]

Yeah, do not have an idle valve and feel no need for one. My hot idle is dead on 850rpm. It does have a little trouble starting on very cold mornings, but I attribute that to the car desperately trying to make oil pressure (which takes a good while).

[progman]

Ok, I tried to idea of cracking the throttle for idle. I hate it. Plus I broke my throttle cable adjustment things. Then I tried to weld it on and it caught fire. I'm not going to touch it again until I get a new throttle cable.

Instead I just used the manual adjustment factory idle air control valve. I ran a hose form that to my inter cooler piping. I few two ver minor vacuum leaks to fix. but my vacuum at idle is around 25 KPA, which my throttle cracked there was less vacuum but idled about the same ?? I don't understand that.
Modified by progman at 4:14 PM 4/16/2009

[The_Chosen_One]

I just used the OEM Fast Idle IACV thingy majigger. I ran the FIDLE wire directly to it, than a ground on on the plug and thats it. Set the FIDLE in Megatune to whatever the defaults were and had a steady idle when the damn thing worked.

Oh yea I welded a nipple on the intercooler piping to run a hose to the IACV.