XFI VSS and DS questions

Evans-Tuning · #1 (**permalink**) 07-18-2010, 12:24 AM

I have a XFI 16 injector and traction control enabled box that I will be custom wiring into a 4 cylinder FWD drag application shortly. The factory rear ABS is a 2 wire mag sensor, which I plan on wiring into the box for the VSS signal. The rear speed is being used for more accurate MPH boost control, as well as more consistent MPH reading.

I want to utilize the trac feature on the box, but I am not sure how to approach the DS speed reading. On this particular FWD application there is a transaxle style transmission that has the factory Hall style VSS sensor with 4 pulse per revolution. The sensor is driven off a gear on the differential located within the transaxle. There is an intermediate shaft that connects the axles to the transaxle.

My questions are:

1. Can the factory transaxle mounted VSS sensor be used for DS input to the XFI? I can make a custom pick-up on the intermediate shaft for DS reading, but the OEM VSS sensor would be giving the same rpm output as the intermediate shaft location since its driven off of the differential.

1. Can a VSS and DS speed input be wired into the XFI, and give correct readings for both channels? The help file shows that A1 and A16 would be used for the rear ABS inductive/mag set-up for VSS/MPH, and A6 and A13 would be used for the DS speed if I am able to use it. From all the searching I have done, the MPH and DS calibration go hand in hand.

I am very familiar with XFI on this particular application, I have made everything work on another drag car awhile back. We were not using VSS and DS readings though.

TurboNova · #2 (**permalink**) 07-18-2010, 02:12 AM

You can use both, the sensor settings have two different pulses per rev for the options. You are right on track for the wiring but don't forget to ground the opposite pulse for either.
You can also use the VSS for shaft if you wish... it is just a pulsing signal and does not know what it really is hooked to. Driveshaft on front wheel drive is the trans axel int shafts but if you can get the same signal from the VSS then use it.