EFI Idle Speed Control Options

[TurboBert]

I’m doing some research to convert my 930 to EFI. So far, I have decided to go with:
1. MegaSquirt II v3 ECU
2. 3.2 Carrera intake using stock rails and pressure regulator
3. Ford EDIS

I’m trying to work out what I’ll do with controlling idle speed and would appreciate anyone’s experience or opinions on what would work best. I know there are generally two broad options: stepper motor IAC, and Fast Idle valves (PWM or on/off).

Which of these is the better approach?

[Candelaria]

Steve,
First try it without Idle speed control, 9 out of 10, it probably will be fine without it, Candy.

[hobieboy]

I'm using MS-1 v3 and don't have IAC nor Fidle valve. In fact, I'm chasing down my fast idle problem - I can't get it to go below 1500 rpm. Think I might have a leak somewhere but just couldn't find it anywhere

I also know others who have EFI-ed theirs without either.

So, my 2 cents - try it without first.

[TurboBert]

Thanks, guys - I'll give it a try.

[David]

If you're in Hawaii you should be fine without idle controls. I left them off my car since I'm in Houston. I got it to idle pretty good but it was a little low when cold. Hopefully now that it's at my tuners he can get it squared away.

[Lukesportsman]

David,

I take your rational is that he experiences less temp fluctuations therefore the engine can more easily compensate with its primary settings. No argument in that aspect. BUT, do/would you find it helpful if you were running say AC? I have not ran idle controls on either of my stand alones but have also not ran many accessories on either car.

[TurboBert]

Good point, Luke. Yes, I do run the A/C continuously and that's bound to have an effect on idle as the compressor cycles.

My gut tells me I'd be better off addressing a solution now before I start. I don't mind the effort and the learning experience, even if it turns out that idle control is not really required in my locale.

[David]

My tuner said I could just have two different idle settings one for A/C on to idle at about 850rpm and the other for A/C off to idle at about 1000rpm.

[Lukesportsman]

David's solution with simply an input switch would seem to work just as easily. If your running a cam with mild overlap or OEM EFI profiles esp. in a sequential injected setup would most likely NOT require this feature and hassle. JMHO Then again as a college student I drove a car for almost 2 years without a choke other than the accelerator pump and my right foot.

[TurboBert]

Thanks, guys.

[David]

Originally posted by Lukesportsman
Then again as a college student I drove a car for almost 2 years without a choke other than the accelerator pump and my right foot.

I did the same thing on my old 78 280Z. It would take a couple minutes of giving it a little gas with my right foot and then it would run great with A/C on or off.

[930gt-40r]

I am doing an Accel dfi setup to my 930 with the carrera manifold and am probley going to go with the Ls-1 camaro throttle body and have an adapter machined for it. My reason for doing this is because the ls-1 already has the tps and iac on it and these sensors are compatible with Accel. For your application, see if the 70 mm mustang throttle body will have sensors that are compatible with the mega squirt. I noticed that the stang throttle body is a very close fit and may even be able to be machined to fit to the carrera manifold without an adapter.

[mppickett]

I'm using the original Bosch air control on the 3.2 intake on my 930 engine. I use the MegaSquirt FIDLE control to switch it on and off (no fine tuning). There's a circuit around here somewhere that shows how to modify the Bosch connections to make it work with FIDLE. I can dig them up if you're interested.

[930gt-40r]

I would like that, but could I use fidle with the accel dfi? or is that something exclusive to megasquirt? Also, how does it work, does it convert the signal to something that the bosch unit can understand?
thanks for the offer.