MSefi.com read only forum (Jan.15,2018)

I'm having a few issues with a new MS2 V3.0 install (tach signal from negative side of the coil, controlling fuel only...not ignition). It seems like all of the signals are very noisy and the last couple times I took the car out it will suddenly sputter for a split second and then drive fine for awhile again (maybe twice in a 30 minute drive). The data log shows a lot of noise on many of the signals (but I really don't know what is normal, this being my first install). I see constant noise in the vBatt with occasional spikes up to 22V and dips down to 9.5V, along with dips and spikes in AccelEnrich, and a lot of noise in TPSdot. Right now everything is wired to a the relay board and I have tried several things:

--Installed inline noise filter to the main power coming into the relay board (didn't make any difference at all)
--Unsoldered X1-X2 jumper on MS board and ran a new jumper to SPR4 to isolate tach ground. SPR4 then is wired all the way back to the engine block in the tach shielded twisted pair
--Replaced the alternator and installed an EMI capacitor on it
--Ground wire for relay board is run all the way back to the negative on the car battery

Not sure if this could be an issue....but this ground wire on the relay board is where I grounded the O2 sensor, and the tach wire shielding (one side only). Also, are the injector wires very noisy as they are not shielded and bundled with all of the sensor wires? Any suggestions would be appreciated.

One other issue, unrelated (I think) is concerning tuning the VE table. I have an issue where I can be cruising along at 60 on flat ground and tune the VE table cell to give me say 13 AFR on the O2 sensor feedback. If I come to a slight inline and have to give it slightly more throttle the O2 then shows is leaning out to sometime 18 or 19 AFR. The problem is that the additional throttle is so slight that the active cell in the VE table based on the RPM and MAP doesn't change, so if I richen it up to only allow 16 on a slight incline, then on flat ground I'm too rich...like 11.5 or 12. Again, any thoughts on this would be appreciated.

The attached datalog shows all the noise I am talking about. The tune is also attached

Do this simple test. Unplug the MS, and check a sensor ground. If it is grounded, the wiring is incorrect. The rule of thumb is all sensor grounds must run to the DB37 connector on the MS directly. The MS is then grounded to the engine block. The theory behind this is to prevent high currents on the main MS grounds being 'seen' by the sensors in the form of noise.

Okay, I unplugged the DB37 from the relay board and checked IAT, CLT, and TPSret, none of which show grounded. I have the O2 grounded to the main relay board ground which goes directly back to the battery negative. Is this correct? The only other think I could think is that I had the shield from the tach wire also grounding at this point, but I switched it to a different point on the chassis and no change at all. Any suggestions would be appreciated.