Yeah, that's the thing with MS and noise problems. You'll never see them until they hit a certain threshold, then they cause so many problems it's almost not worth fixing. Worst part, 80% of the noise is INTERNAL to the MS! This is my experiance across about 40 MS installs, some of which I installed, but most of which were brought to me to fix after the owner tried to install it and did not follow the directions. MS1 and MS1Extra seem extraordinarily noise resistant, as in I can get significant noise spikes on all the incoming sensor lines and as long as I keep the microcontroller power lines clean, they don't seem to mind...but if the noise gets into the microcontroller's power lines, it'll corrupt the firmware *often*.
Pull up an operating MS2 or MS2 extra, and watch your TPS and MAP tracing-especially TPSdot and MAPdot. They will show spikey, errratic behaviour...but the spikes won't be big! 1 or 2 units at most. The problem is that with the TPSDot and MAPdot enrichment, you can't tune the spikes out-they just skew the enrichment. Same spikes show up in coolant temp, IAT, and MAP too...but they are averaged out really effectively so they don't cause major problems.
Best part? You won't see the spikes if you're running High-Z injectors or a resistor box with Low-Z injectors. The issues are mainly caused by using Low-Z injectors, direct coil control instead of logic-level coil control, and direct solenoid control. (like PWM idle control valves.) The way the power grounds and logic grounds are all tied together and are all run parallel to each other instead of perpendicular means all that high-current switching noise gets capacitively coupled and inductively coupled into the logic grounds and sensor input lines. It's poor PCB design-and even though people have been trying to point this out for nearly a decade, the PCB's haven't been updated to remove this problem.
Even worse, you see MS units with hacked and taped harnesses, poorly grounded harnesses, multiple grounding points, etc to combine with all the internal noise-if the harness is less than perfect it's an uphill battle until you correct it.
As to the cheap, easy to tune, Flashable ECM, the LT1/P66V6 ECMs seem to easily fit that bill for 8 and 6 cylinder applications-and there is a cylinder count function in the P66V6 stuff. Only issue is so far they do not support the 2/3 bar MAP sensors yet. I am *probably* going to try and set up the P66V6 PCM on a 4-cylinder soon-they use the same trigger wheel and DIS signaling, so I think maybe if I just set "number of cylinders" to 4, it *might* work. Don't know yet-and will need to rig a test bench to find out.
I'd set the bench up and do it this month but I just got orders for 4 L20B intakes and 3 L20B turbo manifolds...so the shop'll be in full fab mode for a month or so.
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