Idle control with standalone, big questions!

[sil80drifter]

Ok, so on the SOHC (and DOHC) there are two types of valves (three actually two are combined into one).

1) I.A.A Valve - (I.A.A - Idle Air Adjustment Valve) which on it has A.A.C Valve and an F.I.C.D valve. this is the square thing, on the very back of the manifold which has two components:

a)The A.A.C Valve is the Auxiliary Air Control valve, which according to the FSM is "actuated by the ECU by an On/Off pules, and the longer the On pulse, the more air it lets through.This to me is the real idle valve, on the side of the I.A.A assembly, it's the round cylindrical thing with a connector. (brown connector in pic)

b)The FICD valve (the long 6 sided thing sticking out in the back of the I.A.A assembly) on the other hand according to the FSM "Compensates for changes in idle speed cause by the operation of the air compressor (wtf, either A/C or the air pump for eissions) And also has a vacuum control valve installed to prevent an abnormal rise in intake manifold pressure during deceleration." (purple connector in pic)

Then, a completely separate unit is there called the Air Regulator. It is on the side of the intake manifold, a cone shaped sort of thing, which connects witht a thick hose to the I.A.A assemblyThis is the valve that provides anair by-pass during cold idle. It doesn't have a solenoid, and isn't controlled by the ECU, it simply has power and ground, and inside a bimetal element which opens the bypass at low temps and closes it at higher temps. (on the very left in pic, gray connector)

NOW. I am probably going to keep the Air Regulator, because it's very simple, and only needs a [+] and a ground.

The real question is: What to do with the I.A.A? Remove it completely, block off the rear of the manifold, and control idle with the throttle plate?

Leave it there and somehow attempt to control the A.A.C. with the standalone (Megasquirt in this case)? I def won't need the FICD, so I'm not going to connect that one at all, no matter what.

Who has a standalone and has controlled their idle with the throttle plate?

Should I try to figure out how to control the AAC with the Megasquirt? I didn't see much literature on their site to understand how it can be done....

Suggestions are welcome!



sil80
Modified by sil80drifter at 2:49 PM 4/5/2007

[1WheelWonder]

I don't know if this will help you any but i'm using a tuned ecu and safcII to control fuel and timing and have completely stripped the intake of everything except for throttle body and injectors and have a rock solid 900rpm (by choice) idle. My idle is controlled by adjusting the set screw on the TB.

[sil80drifter]

That does help, as I can see that idle can be kept up using just the throttle plate. How's your cold start? Does it idle higher or the same? How is winter (not that I care much but still) starting? So did you take off and block off the idle air valve that used to be in the back?

I am really itchy to just rip it out and make a blockoff plate, and then i'll have a nice place to put my air temp sensor....

sil80
Modified by sil80drifter at 12:00 AM 4/6/2007

[1WheelWonder]

Well I chopped half of my upper runners off so I could weld a custom plenum to it. All the idle/emission crap is on the lower DE manifold except for the swirl control valve which I had the holes welded up.

Warm start is perfect, the car actually idles better than before, the idle crap could have been faulty thus the change.

Cold start isn't bad, I don't have to give it gas or anything but it runs slightly ruff, like a small miss, it goes away in 2/3 mins.

[1WheelWonder]

I apologize for all the spagetti under my manifold (heater hose,fuel, and pcv line)

[sil80drifter]

Hmm... nice! I may keep the cold air solenoid, cuz it only needs + and -, but the idle valve i'll def get rid of... yes! no more crap behind the mani...

Oh and my resolution is so high that I can see a tube there, but the spaghetti is invisible

sil80

[480sx]

Im running MS too, and the FICD valve isnt really needed, especially if you arnt running AC.

I however am, and basically what i did was leave the ECU in for the control of those systems. Also it runs my fuel pump, making the wiring for MS that much easier. The FICD valve is a stepper type, and MS does offer stepper motor control. Im not sure how you would do it, but the guys at DIY autotune implied that you could make it work.

I just figured why bother rigging something up for idle control when whats there works fine.

[sil80drifter]

Well, screw the AAC and FICD. I'll leave the Air Regulator and control idle with the throttle plate.

sil80

[Edub1]

I cringe when I think of doing anything that will affect drivability. I would think most stand alones would control such systems as they are found on most EFI systems.

We are actually discussing this very isse in the GM ECU thread. BTW, thank you for clarifying the roll of each part.

But, I'm sure the Meaga Squirt tech guys could answer your question and I'd bet it has provisions for the IACV.

Would you consider the GM ECU? Even if not, you are invited to get involved in the GM ECU swap thread - this is just the kind of input we need. In fact, I'm going to quote your original post there.

[sil80drifter]

Replied here:zer...43034

sil80

[WDRacing]

Assuming the intake mani is completely sealed aside from the TB, the idle is a simple function of how much air is allowed to bypass the throttle plate. I've seen this done lots of different ways. People have drilled small holes in the throttle plate, people have cracked the throttle plate but the coolest thing I've seen is a very ingenuitive guy build is own IACV.

He took a shutoff valve.



And attached one end to the Cold pipe and the other to the intake manifold via a brass push on bung he simply threaded into the manifold. So simple man, just open the valve for a higher idle...His car was making about 420WHP.

WD

[PapaSmurf2k3]

Looks like some killer ease of adjustablility, like you can crack it a little more/less depending on winter/summer. This is definately one of those smack your forehead and go "Doh, Why didn't I think of that?!" moments.

[The_Chosen_One]

The way I have it is. Originally I had Megasquirt control FICD via the Fast Idle circuitry. aparently the FICD also only needs [+] and ground. So what I did was took the plug off and wired up its power and ground seperate from MS. This works the same and provides a steady idle.

What you can also do is convert to a stepper motor idle control, found on Jeeps. This gives you more precision control for idle.



http://www.diyautotune.com/cat...71651

This is the stepper motor off a 4.0L jeep wrangler 1991-1997



http://cgi.ebay.com/ebaymotors...ZWDVW

480sx the AAV is not a stepper motor, its categorized as a Fast Idle valve.

[sil80drifter]

Looks like a decent idea. I like all of the above.

I will probably not spend any more money on this, I mean, it should idle fine with just the throttle plate adjustment, which has a screw to crack it more or less open (just like your valve WD), and I will retain the Air Regulator for cold starts....

That Jeep setup looks pretty damn nifty though (extra $100 though, with the DIY complement).... But I thought our AAC was in fact a stepper.... not the Air Regulator which IS a fast idle valve but the AAC, the one I referred to as 1) in my first post up there.

sil80
Modified by sil80drifter at 11:14 PM 4/7/2007

[Edub1]

sil80,

IMHO, I would not want to sacrafice 1oz of drivability unless it was absolutely necessary. Like I was saying in the GM ECU thread, why not just remove the solenoid, make a plate with a hose barb and remote mount a stepper unit. I'm sure the GM ones are dirt cheap.

Think about it, you are paying for stand alone functionality - why not maxamize your control over your tune.

[sil80drifter]

The stock AAC IS a stepper unit, from what I understand. I could just keep that. Or the FICD, which could also be controlled by the standalone. I don't see why we need to make things more complicated by buying additional (GM) hardware. I'm not throwing the I.A.A unit out because I don't think I could control it, I am throwing it out because I think THREE idle control valves are redundant on a weekend/track car.

I'm not even sure why I'm keeping the fast idle solenoid, probably just so I don't have to worry about cold starts in the spring/fall. Look at the post of the guy above who uses the butterfly only. He seems to be doing just fine, as well as others I've spoken to in person.

If this was a daily driver and I was at all concerned with A/C and etc, I woudl probably think twice. But this is not the kind of tune-ability that will make or break the deal for me, and I have a feeling that as long as I can get a steady idle, the difference between that and what I could get with the stepper (stock or GM) would be too minute to put more effort into. Time will tell, and I will make video/other documentation of my progress so you and others can see how it works out and if it would be the appropriate path for you.

sil80

[PapaSmurf2k3]

In the garage I used to work at we had a lot of Dodge/Jeeps come in with this litte bastard all messed up, caused all sorts of idleing problems. The valves get sticky and don't move like they should, then they'd have to be replaced. Food for thought.

[Edub1]

If it's just a track car I wouldn't worry about it. I just hate to see a brother out with a little hottie and blow some potential slide hole because your car is acting up - you know.

Are you sure it's a stepper though? A few guys are saying it's not.

[The_Chosen_One]

here's some info on it.

http://www.megamanual.com/ms2/IAC.htm

[Edub1]

Those motors look like they could almost be a direct replacement.

But anyway, that Jeep setup more or less puts the issue to bed.

[1WheelWonder]

Recon I should try and post some videos of cold start and idle and hot start and idle?

[sil80drifter]

Um.... hell YEAH!

sil80

[1WheelWonder]

Expect something soon!

[sil80drifter]

boomp