How to Megasquirt your 3G Hemi
Really glad you didn't brick your Megasquirt ECM. A $600.00 doorstop is not fun. Was your 5v to the crank sensor finding its way to ground, I'm a bit confused?
Good to know about the crank sensor filtering. Whether I have issues or not, it is good to know, every issue someone else figures out is a benefit for the rest of us. :)
Yes, the 5v was finding its way to ground, but only when the box was hooked up (made it particularly hard to find for me). The way I 'found' it was I made a test harness (plug with 3 wires) that went from the harness on the car to the box. I ran a ground, a 12v, and a 5v. I put my multimeter on the 5v, then started walking a 4th wire from pin to pin (making sure I didn't cross connect), and saw where my multimeter dropped from 5v to 1.2v when I tested pin 7. It is a dedicated ground for my crank sensor. Not sure how 5v was finding its way to that wire, but I'm thinking the header heat affected the shrink tubing to the point that a connection was made.
Here's more numbers and math for y'all. Copied from my notes, so it may be a bit difficult to follow:
My VE table is 142.2 VE at 4400 rpm. 13.4:1 AFR at that. MAP of 98.7.*
Also, my MAP reading is 109.7 at 3879 rpm. Over 100 from 3600-4000 rpm. Elsewhere it is ~95-99
The tuner studio VE table uses something called 'required fuel' as a reference. I used 10.4, which was calculated using 44 lb/hr, 348 ci, and 14.7 AFR. If you swap in 13.5 AFR, then it goes to 11.3. So a 8.6% difference. If you take 8.6% off my 142.2, then we're looking at 129.9 % VE.*
More info- my gauge reads lower than my computer. So if it was actually 13:1, then I'm looking at 124.4% VE.
I figure ~125% VE is peak at torque peak (4400 rpm- which is the Tq peak of dudeiwin's 5.7 with this cam on Lxforums)
5800 rpm
77.1% duty cycle
99.6 MAP
80.8% Throttle
13.0:1 AFR (~12.6:1 on gauge?)
Plus-
134.8% VE in table using 10.4 req fuel
=
12.2 req fuel if using 12.6:1 AFR.*
=
17.3% off (mult by table VE)
=
111.5% VE actual at 5800 rpm
So my best estimate for my motor's efficiency:
125% VE at 4400, and 111.5% VE at 5800.
those two points should be real close to tq and hp peaks.
