IAC or no IAC? MAF or no MAF?

[ponie1992]

Hey all, I'm still working on rewiring my MS2 to fit my setup/combo. MS2 was installed by the previous owner and I believe he wasn't using an IAC valve. I'm running a 306 with Cobra intake. Should I use an IAC valve or just adjust it with the idle screw?
Also, should I run a MAF or leave it setup as speed density?
This is a street strip car and won't be daily driven. I'd just like to know what would be best. Thanks in advance!

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[Blown88GT]

You'll never get it to idle under all conditions without the IAC. Idle stop screw is only the base setting. It's like saying: "Can I run the same base timing all the time or the same AFR all the time?"
MAF or SD, or both? I use both, MAF for fuel, MAP for spark.

[ponie1992]

This is how he explained it to me a little earlier:

"Say idle 800rpm. Set idle screw. Set timing at like 10-20*, see where you get highest vacuum. Then, in the timing table, put a block at 600rpm, and go up 2* timing. That way if idle ever falls, the bump in timing brings it right back up"

I don't quite follow what he's saying, but I'm unfamiliar with this system to begin with. I wanna do what's best. I have an IAC valve and a MAF calibrated to the injector size I'll be running.

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[ChevelleFan]

What he's saying about the idle tuning isn't exactly wrong. The idea is that if RPMs drop, the extra timing commanded in the 600 row should help the engine speed recover back up to the 800 range. However, cold starts become much easier with an IAC. I ran without one for a few years, and while it worked, it was less than ideal. Speaking from experience, IAC = much better. Don't Fords use a PWM controlled IAC? Super simple to wire. Spend the extra few minutes to wire & install it. You won't regret it.

-Dave

[ponie1992]

What he's saying about the idle tuning isn't exactly wrong. The idea is that if RPMs drop, the extra timing commanded in the 600 row should help the engine speed recover back up to the 800 range. However, cold starts become much easier with an IAC. I ran without one for a few years, and while it worked, it was less than ideal. Speaking from experience, IAC = much better. Don't Fords use a PWM controlled IAC? Super simple to wire. Spend the extra few minutes to wire & install it. You won't regret it.

-Dave

I'm not sure how factory Ford IACs are controlled. I wanna do what will give me the best results. Wiring up the IAC doesn't seem like a big deal, so if it will be best then that's what I'll do. Same goes for the MAF. I don't mind a little extra work now for better results when the car is running.

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[tryingbe]

Do you want a IAC or not?

You can setup MS not to have idle control at all, but if you have a/c, want idle RPM at all time, etc, you want an IAC

I'm not sure how factory Ford IACs are controlled. I

Start here. Find out how the factory FORD IAC is controlled, then wire it up accordingly.

[Blown88GT]

I'm not sure how factory Ford IACs are controlled. I wanna do what will give me the best results. Wiring up the IAC doesn't seem like a big deal, so if it will be best then that's what I'll do. Same goes for the MAF. I don't mind a little extra work now for better results when the car is running.

MAF won't work unless you have the calibrations curves & enter them into Tuner Studio. Calibrating to you injectors was an EEC-IV work around. Does not apply to Megasquirt.

[ponie1992]

Do you want a IAC or not?

You can setup MS not to have idle control at all, but if you have a/c, want idle RPM at all time, etc, you want an IAC

I'm not sure how factory Ford IACs are controlled. I

Start here. Find out how the factory FORD IAC is controlled, then wire it up accordingly.

I'd like to know what would be best. The car is a street strip Mustang. No AC.

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[ponie1992]

I'm not sure how factory Ford IACs are controlled. I wanna do what will give me the best results. Wiring up the IAC doesn't seem like a big deal, so if it will be best then that's what I'll do. Same goes for the MAF. I don't mind a little extra work now for better results when the car is running.

MAF won't work unless you have the calibrations curves & enter them into Tuner Studio. Calibrating to you injectors was an EEC-IV work around. Does not apply to Megasquirt.

Cool, that answers that question. Thanks!

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[ChevelleFan]

Do you want a IAC or not?

You can setup MS not to have idle control at all, but if you have a/c, want idle RPM at all time, etc, you want an IAC

I'm not sure how factory Ford IACs are controlled. I

Start here. Find out how the factory FORD IAC is controlled, then wire it up accordingly.

I'd like to know what would be best. The car is a street strip Mustang. No AC.

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My Chevelle is street/strip too. Do the IAC. Seriously.

-Dave

[ponie1992]

Do you want a IAC or not?

You can setup MS not to have idle control at all, but if you have a/c, want idle RPM at all time, etc, you want an IAC
Start here. Find out how the factory FORD IAC is controlled, then wire it up accordingly.

I'd like to know what would be best. The car is a street strip Mustang. No AC.

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My Chevelle is street/strip too. Do the IAC. Seriously.

-Dave

Gotcha. Looks like I'll be using the IAC. Thanks!

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[cactus]

One comment. Don't get bogged down trying to incorporate everything right away. I plan to add IAC eventually, but you certainly don't have to have it to get your project on the road. Not having to sort out the idle valve issues with early stages of tuning is a benefit. You can certainly do all the things together, but tuning all things at the beginning can be overwhelming. As you learn, you find things you may want to do differently, so it can be hard to do it perfectly the first time and regret tearing up the wiring you "thought" you would never need to change.

[ponie1992]

One comment. Don't get bogged down trying to incorporate everything right away. I plan to add IAC eventually, but you certainly don't have to have it to get your project on the road. Not having to sort out the idle valve issues with early stages of tuning is a benefit. You can certainly do all the things together, but tuning all things at the beginning can be overwhelming. As you learn, you find things you may want to do differently, so it can be hard to do it perfectly the first time and regret tearing up the wiring you "thought" you would never need to change.

I was thinking along these lines lately. Just get her running for now and then add things in if necessary.

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