Idle RPM: Park vs Drive

[ironwill11]

I noticed that I was doing was working on getting the idle straight and noticed that I got the RPM right where I wanted it, about 650ish but that was in park. I then put it in drive and the load goes on it and the idle drops to 490-500 (sometimes goes below the minimum RPM for VEAL). It still runs and has enough power to get up and go.

To fix I figured that all I needed to do was open the IAC a little more as closing it is what I did to get it down to the RPM I wanted. Then when I put the trans in drive the RPM would drop to where I want it to idle (650ish). When I do this I have to raise it so the idle is around 850 or 900 in park to get the idle to drop to 650.

Is my reasoning on openning the IAC more correct or is this something that I should adjust the tables at the different load?

Is it normal to have a 200-250 RPM drop between park and drive? I have driven't a lot of manuals in the past.

Always appreciative,
Will

[DaveEFI]

There will some drop when you engage a gear, but assuming the torque converter is OK, that sounds excessive. Might be worth posting your MSQ file - the tune at and around idle will make a big difference to how much the speed changes.

[jacky4566]

Can you provide more details. What engine? Stock idle setup?

Sounds like you need more range with the IAC. Or your fuel/ ignition tables are not setup well enough.

Did you build an "idle ignition cradle" into your ignition?

Try reading DIY guide to idle tuning.

https://www.diyautotune.com/support/tec ... egasquirt/

[ironwill11]

Sorry here is the MSQ that I am currently using:

2016-12-08_17.42.45_IDLE DROP.msq

I am using a 4.3 TBI with a HEI 8 pin module. MS2 version 3.0, firmware 3.4 The Transmission is a TH350 (everything is stock).

My ignition circuits were built using the megamanual as that is the only info I had at the time of soldering.

I do not have a datalog of the idle drop as I was tuning with my labtop running VEAL and my battery does not usually last very long.

[ironwill11]

Can you provide more details. What engine? Stock idle setup?

Sounds like you need more range with the IAC. Or your fuel/ ignition tables are not setup well enough.

Did you build an "idle ignition cradle" into your ignition?

Try reading DIY guide to idle tuning.

https://www.diyautotune.com/support/tec ... egasquirt/

I did not build "idle ignition cradle" into my ignition that I know of (I am not that sure what that means). I am going to read the website now.

[turbo conversion]

Have you achieved a stable idle in the 600 to 1100 rpm range?

David

[ironwill11]

Have you achieved a stable idle in the 600 to 1100 rpm range?

David

Yes I believe I have. I can control what RPM it is at with the IAC, I was usually keeping it between 650-670.

[turbo conversion]

If the idle is stable then set IAC to IAC Closed-loop always-on.

You can then start tuning the IAC so it will keep idle at target.

David