'70 Dart 392 Project; what direction?

racerjoe said
I think the idle valve is always a guess. It's easy to determine which pins are the coils, but the polarity is a shot in the dark. Mine seemed like it was correct initially, but quickly realized it only moved one direction. It's as simply as reversing polarity one of the coils to make it correct. The "output test mode-stepper motor" feature under "CAN-bus/testmodes will be your friend in getting the IAC right. I've always said setting up the IAC on tuner studio is by far the most frustrating thing of the whole system. The problem with the IAC is the ECM doesn't have any feedback from it to know where it is. When getting your start right, often times the IAC can miss some steps if the engine doesn't start cleanly. You'll end up with a high idle but the steps in tuner studio are showing the correct value. The only way to correct this is turn it off and start over with a clean start. I've never had any luck with closed loop idle either. I tried many times, but I found it best to just leave it run open loop based on temperature, then set your idle VE and ignition advance. However, I have noticed this G3 Hemi doesn't respond to timing changes at idle like my small block did. The hemi doesn't seem to care what idle timing is, unless you go to extremes.

I HATE guessing lol
Turns out I had my idle screw on the throttle valve about 3/4 turn too much and it was causing a high idle. Now that I figured that out, I discovered that my Holley alternator isn't charging. Charging "+" post (one post alternator) is only reading 11.7V while running, which is throwing my O2 sensors off and they're showing an E9 error for low voltage.... So the computer can't make any adjustments to fuel without the O2 sensors working. It's only doing timing adjustments. Sent an email to Holley about it.

I finally removed the IAC valve from the TB and under the "test" function, if I "Home" the IAC the plunger extends (which would restrict airflow past the throttle body), and in the "run" position it retracts which would allow air flow. The HOME function bottoms out the plunger which blocks off all airflow. Then the "run" step size down from that retracts the plunger the specified amount to allow air behind the throttle blade. I've played with this darn thing all day and haven't made any improvements. If I home it, it blocks off all airflow and kills the engine. It will high idle and rev great above 1150RPM but if it goes below 1000RPM for more than 1 second it putters and dies. The exhaust smells extremely rich, I think I need my O2 sensor issue fixed before I can dial in this idle.

Have tried fixed timing at 10/15/20 degrees with no improvement. The preloaded tuned that came with the ECU has upwards of 35degrees timing and that only helps so far in that it keeps idle over 1,100RPM.

Mike