Last week I was able to install and hook up my MegaSquirt-3 Extra ECU in the Dart, which I had been benchtesting recently.
The ignition system consists of a stock (Chrysler LeanBurn) distributor, a HEI 7-pin module, and an MSD TFI e-core coil.
Now, the MegaSquirt ECU is connected to the HEI-7 module which runs in ‘bypass’-mode when the MegaSquirt ECU is powered ON.
At engine start, the HEI-7 is providing pre-set dwell-time and ignition timing to the coil.
3 seconds after engine startup, the MegaSquirt ECU takes over timing advance and dwell time from the HEI-7 module.
I already had built an ignition advance map up front to use as a baseline setting for the engine to run on.
During the first testrun around the block I already noticed an improved and snappier acceleration of the engine going through the rpms.
Before the 2nd run I changed a few numbers in the spark advance table and felt another slight improvement.
I’ve been using the current setting for the rest of the week commuting to work and around town.
The engine is more responsive in pretty much all its rpm-ranges. High speed highway driving feels easier on the engine and requires a little less throttle.
For further testing and improving, I made a few alternate ignition maps with minor timing curve alterations to try out and to see what the engine likes most.
At the moment the MS3x ECU only controls ignition based on engine RPM and intake vacuum. Pretty soon I will connect some more sensors input to the MegaSquirt ECU, like engine coolant temp and a AFR o2-sensor so the ECU can refine its output better on the engine state and condition.