I have a couple of questions regarding basic modification of the 88-93 EEC-IV ECU calibration (assuming that I have a programmer) when applying the following changes on the engine.
1. Gaining more cubic inches
As far as I have seen on the various forums over the years I only need to change the engine size variable on the calibration in order to reflect the right Engine capacity. ENGINE_DISPLACEMENT variable and maybe the STARTUP_FUEL_TABLE in order to compensate during open loop mode.
2. Installing bigger fuel injectors
It is recommended to change the HIGH_INJECTOR_SLOPE variable for the right size of injectors
3. Installing an Aftermarket MAF
Basically it is recommended to modify the MAF_FUNCTION table with the right "MAF transfer function". However the confusing part is that some of the aftermarket MAF sensors are calibrated for different type of injectors. If I load a right transfer function do I also need to modify the HIGH_INJECTOR_SLOPE variable as per #2 in order to reflect the right injectors or do I have to leave it to the 19lbs values since the purpose of the calibration is to confuse the EEC into thinking that it is using 19lbs Injectors? I used the "EEC Analyzer 3.0.1" to compare some MAFS and it confuses the hell out of me when I see a C&L 73mm with a green sampling tube having an 1850 Airflow at 5V versus 1350 at 5V for the same MAF with a blue sampling tube. How is this possible that the MAF flows more?
4. Installing an aftermarket Camshaft
From what I have seen the INJECTOR_TIMING_TABLE needs to be modified in order to fire the injectors at the right spot based on camshaft profile. The "EEC Analyzer 3.0.1" provided good tools on this.
Does anyone have to make any recommendations?
Finally does anyone know how far the MAF EEC-IV can handle in it's stock calibration without having to reprogram it?
1. Some folks try to use the displacement to 'correct' for afr and such.
However you are correct, the CID change is a simple scalar mod.
2. I would change the High and Low slopes. You will need to play with these settings to get the KAMRF's and AFR exactly where you want it though.
3. There are MAF Transfers available for most combinations/calibrations of MAF meter. I have links to many of the PMAS and C&L meters on my site (in sig).
EA can be a big help in getting the MAF Transfer nailed down, but I prefer to load a Transfer, and then make tuning changes in the fuel settings.
4. EA does a pretty good job of correcting the injector timing. My idle quality settled down quite a bit with this change.
I have some info on getting started with tuning on my site, if you want to check it out. It is geared toward tweecer though.
The factory X3Z tune handled my 408w pretty well, before I started using the tweecer. It runs much better with the tweecer though.
hope that helps,