m20 RHD ITBs idle

[zaq123]

Alright, should I use ICV or not? I got it all setup for ICV already (vac lines) and MS is pretty simple to set so it runs ICV....my concern is potential vacuum leaks down the road, would like to keep the setup as simple as possible. Anyone in cold climates have any starting issues with ITBs and no ICV? Another alternative is to install some sort of high idle cable but I just want to finish this project already (has been way to long) and at the same time don't want to take any shortcuts

[hoveringuy]

You're going to want to have an ICV. The idle air requirements between cold and hot are way different and you'll find it extremely annoying otherwise.

[Luke758]

In order to properly use an Idle air control valve, you will need to completely close the ITB's and in most cases ITB's are not designed to be closed, as in they remain open just a touch to allow for normal idle airflow. If the RHD ITBs have a fully closed position, then there is no harm in a properly installed ICV setup. If they do not, you can still run them but you will have to balance the airflow between the ITBs and ICV to maintain your desired parameters, and using another method such as an adjustable high idle cable may be simpler. Assuming a properly installed setup, you should not have issues with or without an ICV.

For more info on running ICVs with ITBs, watch this video on my YouTube Channel- https://www.youtube.com/watch?v=xvFZjo5PgG0

[zaq123]

there are a plenty of ITBs that just run on Alpha-N and no ICV....wonder if there were any known cold idle issues with that setup

[digger]

You will want icv on a street car it’s much nicer for cold starts and running A/C. You seem like the kind of person that doesn’t want compromises

[varg]

There are known cold start issues on regular single throttle body cars without an ICV... I've tuned a few of those over the years. The more aggressive the engine the worse it will generally be, high compression engine with an overlap happy cam for example. If the engine is aggressive enough to warrant ITBs you're going to want an ICV for cold weather driveability, if the car has AC I'd consider the ICV non-negotiable unless you want a high hot idle. Especially if you have a lightweight flywheel.

[e30davie]

On the megasquirt using a 2 wire is so easy, just 1 output. So i dont see any reason not to have. I used a ford one on my m20b23, but any will work really - just gotta plumb it up.

I put a small modern sanden AC compressor on my m20b23 and it doesnt seem to effect the idle much at all, the old R12 unit certainly did though.

Even the most basic idle strategy will be very beneficial but PID is nice though, but does take a bit of playing around to get it right.

[zaq123]

There are known cold start issues on regular single throttle body cars without an ICV... I've tuned a few of those over the years. The more aggressive the engine the worse it will generally be, high compression engine with an overlap happy cam for example. If the engine is aggressive enough to warrant ITBs you're going to want an ICV for cold weather driveability, if the car has AC I'd consider the ICV non-negotiable unless you want a high hot idle. Especially if you have a lightweight flywheel.

thank you guys for the input. It's all that: 2.9L with 10:1 and AC

[zaq123]

You will want icv on a street car it’s much nicer for cold starts and running A/C. You seem like the kind of person that doesn’t want compromises

just looking more into this and have a follow up question:

.What mode do you guys use with ITBs and ICV (blended - Alpha N/Speed D)?
As I understand, one can't run with pure Alpha-N and ICV(closed or open loop)
as fuel pulse width will be wrong with the additional air and zero input from TPS?

Am I understanding this correctly?

[ForcedFirebird]

Since you'll need a vacuum block of some sort, can actually use that for MAP signal.

You can just dial PW in with your VE table for the idle, even in Alpha N.

[digger]

just looking more into this and have a follow up question:

.What mode do you guys use with ITBs and ICV (blended - Alpha N/Speed D)?
As I understand, one can't run with pure Alpha-N and ICV(closed or open loop)
as fuel pulse width will be wrong with the additional air and zero input from TPS?

Am I understanding this correctly?

I don’t use MS.

In any case you can run Alpha_N but you need a fuel correction based on the ICV duty cycle otherwise as the ICV position changes more or less air is introduced. This is analogous to throttles moving without tps knowing. If you have Closed loop WB will be ok in any case

[zaq123]

Since you'll need a vacuum block of some sort, can actually use that for MAP signal.
.

using MAP with Alpha would be ITB mode (low load MAP going into Alpha at the high load, the same VE table)....no?

[zaq123]

I don’t use MS.

In any case you can run Alpha_N but you need a fuel correction based on the ICV duty cycle otherwise as the ICV position changes more or less air is introduced. This is analogous to throttles moving without tps knowing. If you have Closed loop WB will be ok in any case

regardless if one uses MS or something else.....how is your setup configured? Do you use MAP at all with your ITBs (baro adjustments or as the actual MAP)?
MS has 2 types of ICV arrangement: closed loop - ICV works to maintain chosen rpm (load changes, A/C etc) regardless of the engine temp. and it has an open loop mode (ICV is used during the warm up (cranking or idle).

How is ICV configured in your ECU?

[ForcedFirebird]

Seems there's two camps on tuning strategy.

MegaSquirt uses VE (fuel) and spark table, much like an early Bosch or domestic system.

Most other ECU's are really open source. AEM was an early algorithm that most follow today.

Setting that aside.

Zaq, where are you on the start, idle, rev of real world data?

[zaq123]

Seems there's two camps on tuning strategy.

MegaSquirt uses VE (fuel) and spark table, much like an early Bosch or domestic system.

Most other ECU's are really open source. AEM was an early algorithm that most follow today.

Setting that aside.

Zaq, where are you on the start, idle, rev of real world data?

decided to push the fun stuff until after the holidays, too hectic at the moment. Just playing with the tune, ICV and different configurations on JimStim when the time allows.
Looks like the only real option is to run ITB mode (MAP/AN blend) in order to properly utilise ICV