Idle control for ITBs

[hozzziii]

This is probably going to make a lot of people roll their eyes but I couldn't find the information elsewhere so here we are. 

 

Question: how do cars with Individual Throttle Bodies control their idle?

Do they have a minimum opening on the butterflies?

Do they have a small sort of "vacuum pipe-like" goin to behind all the butterflies?

 

You know what I was thinking? If it was the latter method, we could get a CIS head, the one with the injector holes in it if I'm not mistaken, and put in those pipes through those injector holes! That would look so good. 

Anyway, sorry my mind goes crazy sometimes. 

Any ideas anyone?

[tzei]

3 hours ago, hozzziii said:

Do they have a minimum opening on the butterflies?

Do they have a small sort of "vacuum pipe-like" goin to behind all the butterflies?

Yes - at least i have minimum opening.

Yes - ecu in my case needs to know intake pressure. All intake ports has a small tube going to common chamber. From there small tube goes to sensor via tiny filter. Filter is there to further balance pressure fluctuations so ecu sees somewhat nice curve.

Ecu adjusts advance and fueling to get stable idle.

 

Also separate idle motor can be used to adjust idle airing as in oe systems.

[jimk]

31 minutes ago, tzei said:

Yes - at least i have minimum opening.

A static opening setting, not variable which is what the OP is looking for to make it idle at the same rpm, cold oil or warm oil.

[jimk]

4 hours ago, hozzziii said:

That would look so good. 

And get you a very stratified charge and burnt valves.

[hozzziii]

1 hour ago, tzei said:

Yes - at least i have minimum opening.

Well what brand is your ITB? or did you make one?

 

1 hour ago, tzei said:

All intake ports has a small tube going to common chamber.

Do you have a picture of this chamber? Also, what sensor are you using? MAP or MAF?

 

1 hour ago, tzei said:

Ecu adjusts advance and fueling to get stable idle.

And how is your idle in different weather? any troubles? fluctuations?

[hozzziii]

37 minutes ago, jimk said:

variable which is what the OP is looking for to make it idle at the same rpm, cold oil or warm oil.

Exactly, I'm not sure which company supports this.

I saw a video on E46 M3

Interesting, if you look at the manifold at 2:00, there's this hole that a hose connects to. A few seconds later, you can see that the idle control valve is controlling the airflow there. So from what I understand, air comes from the airbox, through the control valve, into that pipe that looks like a fuel rail, the one to the further left on the engine, that pipe seems to distribute the air past the butterflies. 

I like this method. Problem is none of the ITB kits for the M10 I've looked at seem to have at least, this "opening" behind the butterflies, although I could tap through...

 

This is why I was confused about idle control with ITB kits.

[tzei]

My itb's are made from Al blocks using dellorto's repair kit. Pneumatic industry chamber is just under manifold. Black tubes connects from every runner to it. Idle is high -ish: 1100 rpm or so and steady - no problems - cold start idle could be tweaked to be better but honesty haven't bothered. I'm happy as it is.

[TobyB]

Yup, it's a perennial problem.  Adds a lot of plumbing to what ought to be an elegant design,

for something that just needs to be a small, controlled air leak.

 

The old- fashioned way that Spica did it was just to hold the throttles open with a warm- up

'valve' that was at least half thermostat.  They also had the vacuum taps that tzei mentions,

with a little plenum to give an averaged 'vacuum' signal analog.

 

Modern engines have lots of plumbing- the later M42 had air- pressure equalization

on the BACKS of the injectors just to compensate THEM, for example... 

 

Jim, why don't you like using the CIS injector location for idle air?  It's just another head- port location?

(I'd use 'em for injectors, myself, but just because I think hitting the intake valve is 'cool')

An E30 1.8i head still has the CIS bosses, but they're not drilled- so anything could go there.

 

t

[jimk]

2 hours ago, hozzziii said:

A few seconds later, you can see that the idle control valve is controlling the airflow there. So from what I understand, air comes from the airbox, through the control valve, into that pipe that looks like a fuel rail, the one to the further left on the engine, that pipe seems to distribute the air past the butterflies

The same method is used on the stock S14.  Additionally there is a hot idle manual valve in the branch coming  around the idle control valve.  The butterflies are not adjusted for idle speed, but are adjusted to a bench setup procedure.  This is in addition to the balance air bypass screws on each throat. The air bleed port on the runner is strategically placed to get the air mixed at about the point of the injector.

My M10 had TWM itbs (but gone for other adventures) and I drilled a port on the bottom side tapped for a 0.250 od tube connection and ran each short run to a 3/4" copper tube suspended below the itbs.  At the end I had a stepper idle air valve connected.  Crude but worked.  The drilled port was at or upstream of the injector..

Yes if the 1.8l head with the port openings had the injectors, anywhere upstream of that point for a idle air port would not affect the fuel mixture.

[hozzziii]

1 hour ago, tzei said:

My itb's are made from Al blocks using dellorto's repair kit. Pneumatic industry chamber is just under manifold. Black tubes connects from every runner to it. Idle is high -ish: 1100 rpm or so and steady - no problems - cold start idle could be tweaked to be better but honesty haven't bothered. I'm happy as it is.

Riiiiight I see that "chamber" you mentioned. That's a neat idea. And the heater return goes below it, so no problems there. 

Waaaaaa is that a dry sump kit you're running??? Very impressive ??

[hozzziii]

1 hour ago, TobyB said:

An E30 1.8i head still has the CIS bosses, but they're not drilled- so anything could go there.

My car is an E30 1.8, could look into it...

[hozzziii]

49 minutes ago, jimk said:

Additionally there is a hot idle manual valve in the branch coming  around the idle control valve.  The butterflies are not adjusted for idle speed, but are adjusted to a bench setup procedure.  This is in addition to the balance air bypass screws on each throat. The air bleed port on the runner is strategically placed to get the air mixed at about the point of the injector.

I swear I read this part like 6 times, still could not understand hot it worked. I'll do some more research and find some manuals to understand that better. 

 

49 minutes ago, jimk said:

Yes if the 1.8l head with the port openings had the injectors, anywhere upstream of that point for a idle air port would not affect the fuel mixture.

How about this:

I put the bypass hoses on the ITB holes for the injectors. And then put the injectors in the holes on the head. 

Could work, maybe. 

Edited August 5, 2019 by hozzziii

[tzei]

Thanks hozzziii. Dry sump "kit" uses a Pace pump, Are oil pan and Moroso gears (Tii crank hub).

[hozzziii]

7 minutes ago, tzei said:

Thanks hozzziii. Dry sump "kit" uses a Pace pump, Are oil pan and Moroso gears (Tii crank hub).

I know, that's realllyyyyy top tier stuff, out of my budget for sure. 

[TobyB]

Quote

 The air bleed port on the runner is strategically placed to get the air mixed at about the point of the injector.

 

Ah, right- if the injector's shooting into the port, but the idle air is downstream of it, then what's going to get the

fuel into the cylinder!

 

t