MSMLove

Hello Everyone,

I'm not sure if this section is where I post megasquirt so please move it as needed, thank you.

I have a msm with 99 built engine and msmpnp ms3. I've gotten it tuned awhile ago and everything is going great. I decided to install the skunk2 manifold, 64mm throttle body, 100amp alternator. The car is running on 91 octane. Now when I start up and drive the car drives perfectly fine but once I turn off the car and try to turn back on it just stalls and die. If I wait for it to cool down then start it, then everything is fine. I was told the 64mm skunk2 throttle body does not provide enough air to the IACV and that could be causing the issue. Before I switch back to the stock throttle body I was going to see if anyone has a fix or know of a fix.

HowPrayGame

I had to turn the throttle stop screw on my Skunk2 to get a decent idle. To calibrate it, turn on IAC test mode, close the IAC Valve entirely, and then turn the screw til the car idles at 750-800 RPM. This should be the minimum RPM floor the car reaches.

You will probably need to recalibrate your closed loop idle initial value table at the very least as well. I had to bump up values around 3 in every area. (Not used in open loop idle)

EDIT - Upon looking at the tune you are using open loop idle control, I would strongly recommend looking into setting up a closed loop system as it will idle much better. Turning the idle screw may fix it up enough for the car to not stall when starting while retaining an open loop idle.

MSMLove

Should I open up the screw or tighten the screw? Also as for Open Loop setting, it was done by my tuner. I was also curious to why he left it on open loop but never gotten into asking why.

HowPrayGame

Backing out the screw should = more air coming into the throttle body air bypass.

If you ever aren't happy with your idle performance, DIYing idle tuning isn't bad at all and generally yields a much better idling car. Worst case you revert to your current idle settings and try again later. PedXing's video series pinned here should describe how to get started, if you are interested in having a go at it yourself.

MSMLove

I tried backing out the screw but still same issue. I noticed it is idling a little lean after warm up 15:1 but drives perfectly fine at 14/14.7:1 But I don't think that's the cause of the start and stall after warm-up.

HowPrayGame

It should be idling leaner than before as open loop idle (if i recall correctly) does not respond to changes in more/less air, as the screw was backed out it increased the amount of air going in and the open loop idle doesn't inject any more fuel to compensate for more air.

Check the open loop idle tables that are in the warmed up coolant region, I don't know what the tables do but your solution should be somewhere in those tables. The IAC% value when warm looked very low

MSMLove

Sorry, I meant ever since I installed the skunk2 manifold and throttle body the cars been idling pretty lean. I'll try to mess with the idle later, after warm up issue when turning off the car is my main concern right now.