This is basically what I just sent to Jeremy @ FM, but I thought I'd post it here (and any responses of his):
Two quick questions:
1. My front harness and dash harness are out of a 93 CA car, so it has the VSS signal going into the ECU at 1M, which doesn't seem to be wired up to the Hydra. I see the VSS+ and VSS- marks on the Hydra harness. Do I need to do a pull-up off the 1M wire to VSS+, and then tag a ground to VSS-, or something like that?
2. I'm getting some pretty nasty MAP noise, which is similar to what I had with the AEM. On the AEM there was a MAP filter setting, but I can't find anything (or any internet mention of one) on the Hydra. Is there anything I'm missing or do I need to find some sort of physical solution (it's been suggested that I use a small lawnmower fuel filter on the vacuum line)?
Spent the week roughing in the fuel map, and got the car dynoed today. 308rwhp, a little down on where I was with the AEM, but I'm also using a much more restrictive intake than I was at that last dyno, so I'm okay with that for now. Time for a smaller SC pulley...
The power numbers were pretty uneven, so we didn't push timing a bunch. I'm guessing it has something to do with the noisy MAP signal, since the logged fuel was jumping around quite a bit:
These are 4 runs, after we nailed fuel down, adding 1 degree of timing per run (after the red run):
The average is pretty consistently going up, but it's hard to repro it to be very scientific with the power fluctuating like this, so we cut the session short until I can figure out what's up with the fluctuations.
Any other ideas for things to check causing this? The MAP signal is going +/- 2psi or so under WOT runs, so it's causing some pretty drastic shifts in fueling. I've locked the timing across the whole range it swings between, and the datalog shows consistent timing, but irregular fueling as a result of the MAP jumps, so I'm just assuming that's the issue right now.