High Idle on Cold starts After Full Warmup

[slantsix]

Hello.

Here are the Vitals on this Topic:

1979 Plymouth Volare with megasquirted Slant 6 Engine.

Mega Squirt II with V.3.57 Board, I stll use megatune for tuning as My laptop barley survives running XP.. It's super slow and cannot run Tunerstudio (i have to buy a new one that is fast.)


Anyway I Recently Upgraded from the stock MPX4250 Single sensor to the Map daddy 4 Dual sensor. http://www.DIYAutoTune.com/catalog/mapd ... p-117.html

I have updated the .INI file for the new sensors and asked Megatune to run the 2 sensors for barometric correction.


The High Idle is a bit better now with the dual sensors after a cold start and full warmup, but I still have to do a restart when the engine is hot to get the idle to settle down to ~800 RPM.


Here's what happens - cold start - Coolant below ~40*F - Engine warms up to 195*F after 10 minutes driving.. Idle is now at 1200-1600RPM... IAC shows 255 - Full Closed..Hot setting. Then at this point I do a "hot Restart" meaning I shut the engine down at operating temp - 195*F and then Restart it ... High idle for 5 seconds... and then it settles right down to ~ 800 and is fine for the rest of the day / Trip.



What am I missing here?? I assumed that switching to the Dual sensors with the Baro correction would fix this problem, but it has not really been the case.

Any help is appreciated..

Greg

Photos of recent install Below:

Old Sensor Removed:






New Dual map Daddy Sensor on the Main board:

[Matt Cramer]

Please post a data log of the issue and a copy of your MSQ. This will give me more to go on.

[portmod7]

Mine is doing the exact same thing. Its like my IAC doesn't close all the way until I cycle power to the ECU with the engine at operating temperature. I'm very interested to see what you find out.

[Mike Hemingway]

If Matt does not see something in the data here is what I did to understand the IAC operation. I removed the IAC from the car and plugged the holes. Then I made an "extension cord" long enough to get it to the driver's seat area. I powered up Megasquirt without starting the engine and observed the pintle operation on Megatune. It took a few tries to get the Start Value correct. Then I started the engine and let it warm up while observing the steps and blowing through the IAC to determine that it went fully closed at 180 deg. F coolant temp. I also have tweeked the steps at cold temps a couple of times to fine tune the idle speed but it is working perfectly now. I got the best results with IAC stepper always on.
Mike

[portmod7]

I think I may have fixed mine. I changed the"Minimum Number of Steps" to 5 from 1 thinking it might drive the pintle into the seat a little more reliably. For whatever reason it seems like it has worked.