• Hello Guest, welcome to the initial stages of our new platform!
    You can find some additional information about where we are in the process of migrating the board and setting up our new software here

    Thank you for being a part of our community!

1990 Volvo 740 B230FT - No IAC with Megasquirt 2

J

Jushsy

New member
Joined
May 15, 2024
Hello,

Does anyone know what performance/quality of life issues I could run into tuning my car without an IAC? I just have a ball valve off the intake that I am getting dialed for idle. Will this cause issue with things like a lean AFR, hi temps, or just running things like the A/C?

Thanks,
 
Yes, but no. There are ways to get around not having an iac. And you could just use the throttle stop to set the idle. No need for a ball valve.

Create a couple rows below your idle, and add timing in those areas, and may need to play with fuel. But basically set your table so that it picks it up out of those areas when you put a load on it.

But ball valve works, I used one as a choke, cable inside the cabin and on really cold mornings it would let me idle up to around 15-1800rpm.
 
Thanks for the reply!
A few things I am running into is tuning the VE table on cold start vs warm. I currently have it where the ball valve is about 25% open and the car will start and idle around 900rpm. Once it gets warm, it starts to idle around 1200, which in my head seems a little high (actually sounds pretty good) but it might be fine.

You're saying adjust the Ignition and VE tables to compensate for the RMP range in cold/warm areas, all with the ball valve closed? I live in Minnesota, so it gets pretty dang cold here.

The choke idea makes the most sense to me in my head, but I kinda would like to automate the warmup as much as possible. I am worried about setting my idle with the throttle cable as I don't want a high idle when warm.

I am still learning a lot of this, but I feel like I've come a long ways since I started my tuning journey.
 
Get the warm idle where you want it, 700-1000 rpm (in this case higher works better) and set the area lower than that with slightly higher timing and slightly higher fuel. Then using your warm up tables, tune in your warm ups. Sometimes it takes a while to get the warm up sorted. You only get one crack at it per day, and each morning may be different. But 2-3 50f mornings and the 45-60f cold start should be good, then a few 30f mornings and the next set should be good, and after a while you can smooth out the steps and have a year round starter. Once that’s done, the ball valve is only there to idle up when you need it to get the juices flowing.
 
Okay that is starting to make a lot of sense.
So, I should my steps would look like this:

Crack the throttle open with adjustment screw, all with the ball closed when warm
Find where warm idle likes to sit on the VE table around 700-1000rpm
Adjust the spark table slightly higher in the area just behind where the warm idle sits
Then start tweaking the warm up tables during each cold start to get it where I like.

Thanks for replying as well, this is super helpful and fun to learn. I just want to start driving lol.
 
I’ve used the LH2.2 throttle body in many setups, it has a large plastic air bleed screw for idle adjustment. Works great, looks factory.

As far as tuning and starting goes, on really cold morning you have to lightly crack the throttle for the engine to start. Then after 5-10sec it’s running well enough to just idle regularly, but it’ll be a bit rough.

Timing table to smooth/stabilize the idle is key.
 
If you want to try setting up closed-loop idle at some time in the future, there are a few good threads, such as:

Microsquirt Closed Loop Idle Tuning

1986 765 b230ft (95 block) +16v + stock 13c garrett turbo with stock boost + microsquirt I am trying to wrap my head around getting closed loop idle to work. I am very new to this and I have gotten pretty far on my own so far but I need some help now :lol: I started by tuning the idle with just...
turbobricks.com turbobricks.com

It's a lot more involved, but is really nice if you live somewhere where the temperatures change a lot through the year.
 
Harlard said:
Very much this.

I like having an IAC, but as others have mentioned, there are workarounds that function mostly okay. The ball valve to set cold idle speed manually would be a fine one.
Click to expand...
Ball valve/air bleed and solenoid based on coolant temps would be fine and easy enough to control as well.

Basicallly the old GM(?) style idle control with an air flow adjustment.
 
I also use a lh2.2 throttle body and deleted my IAC with my microsquirt setup and had no issues with cold starts.
 
You must log in or register to reply here.
Back
Top