charger758

Have any of you guys ran into this?
Just built an LQ4 based engine with an LSA supercharger and a Nick Williams 90mm Cable Throttlebody (LS1 IAC), controlled by MS3 gold box.

I am just getting the idle/starts dialed in and am finding the IAC doesn't have enough range.

A 50F cold start, with IAC full open I get about a 1300rpm idle and the velocity of air flowing through the IAC is so fast it is insanely loud.
At full warm with the IAC full closed I get about 700rpm.

I would live with it, but..
My starts could be better if I could get more air into the engine, the loud intake noise is obnoxious, worried about really cold starts being able to start decently.

Anyone else having this issue or do you all run a DBW setup with an LSA blower? or am I going full retard ?

Thinking of adapting an external, larger IAC Motor

V8sounds

iTrader: (1)

I'm unsure if there is a better way, but guys used to drill a small hole in the throttle body plate to allow some extra air in, and just use the iac to find tune from there.

charger758

I can open up the throttle stop to get more air in which would be like drilling a hole in the TB. This will help my cold starts, but will also raise my idle speed when fully warmed up.

stevieturbo

And opening the blade would be the very obvious thing to do when you say you need more air that you believe cannot be provided by the air valve..

And no it wont raise the idle, that's the whole point of the idle air valve and tuning idle control settings. It's up to you ( who I presume is the "tuner" to find that balance that works ), and presumably also you have an ability to use ignition timing to control idle too which should be used.

charger758

Not sure if you read my whole post or not....I'll break it down.

With the throttle blade stop at a set position, IAC full open=1300rpm, IAC full closed = 700rpm. Can't change that range with tuning the idle control.

If I open the throttle blade more or less it will shift that rpm range not expand it like I would like.

Worried when it gets really cold and engine friction is higher my 1300rpm cold idle will only be able to max out at 900 or so.

rotary1307cc

iTrader: (5)

Show a pic of the iac circuits and layout

Porting the iac circuit made a HUGE difference for me in the range it had

charger758

I was thinking the same thing today, glad someone can confirm it helps!

I did port the air filter side of the IAC port and I didn't notice an increase in range, but it cut down on the intake sounding like a jet engine quite a bit.

Maybe the supercharger side of the port needs to be opened up too. I'll try and get some pics next time I dig into it.

Thanks

stevieturbo

And how much more range do you need ?

And maybe you didnt read my post...ignition timing can also be used to very good effect for idle control.

charger758

I struggle with reading comprehension without pictures

The way I like to tune idle is to find an IAC position that gets me near the rpm I want to be. Then find the base ignition timing that is somewhere between glowing red headers from being too retarded and being jumpy due to being too advanced when load changes (AC/alternator/power steering loads...) occur. Then setup the ignition to timing to do fine corrections when the rpm is off of target.

My last car I had so much range with the IAC, I could stall the engine from closing it, I could bounce it off the rev limiter if it was full open.

Now that I got the IAC to not sound like a jet engine (was louder than my exhaust), just want a little more airflow range. I don't want to find when I try to do a cold start at say 30F, there's so much friction between the engine/supercharger that it has like a 900rpm idle. Also would be nice to lower my idle speed a little more than the 700rpm I am currently at since I have a sissy LS9 cam.

ddnspider

iTrader: (26)

The passage was fine for stock LSA vehicles, but isn't for a swap? Seems odd unless there is some monster cam at play.

charger758

LSA engines all used DBW throttle, thus no IAC motor. I am using a drive by cable throttle with IAC motor.

I would have went DBW, but I am running an MS3 gold box which doesn't support DBW.

ddnspider

iTrader: (26)

Ah, that makes more sense. I'd do what Stevie said and adjust the throttle blade instead of drilling since you can undo it. Then adjust spark from there.

qweedqwag

I would try and port it out some more, I had to do that to mine to reach lower IAC counts, I ported the TB side and the intake side to get enough air thru it. You can also adjust base timing to control idle as well.

Jwooky

Dont get it 700-1300 seems like more than enough range.

You want to idle outside those limits?

rotary1307cc

iTrader: (5)

Do people even read?