3rdgenZ

iTrader: (1)

does anyone have any experince with the XFI system for TPI? how easy was it. any suggestions for any DFI will work. this one just cought my eye.
i have an 85 ECM and iam looking to upgrade.

Thanks for any help,
Mike

ws6transam

I converted from an Accel GEN6 DFI to the FAST XFI in only one day. I used their harness though. My experience is that you will have to do some wiring as their generic TPI harness has the wrong lengths to make it pretty. I'll be significantly modifying my harness later this spring.

The XFI lends itself to TPI rather nicely, actually since it uses GM sensors. You'll be reusing your knock sensor and its controller, plus you will reuse your coolant temp, IAC, and air temperature sensor. You will be removing the MAF and converting to speed density, so you will need to add a MAP sensor.

Tuning is rather easy with the wide-band O2 sensor. I've got a crude base tune that took me all of about thirty minutes to create. It gets the job done, but when I log the data, I see where the engine goes rich in the weirdest of places, so there is plenty of work left for my tuneup. I go in to the dyno sessions in early May for the tune.

3rdgenZ

iTrader: (1)

sweet thanks!

smokefan

yea i am looking to convet over to the fast xfi system. right now i am running the stock computer with a custom tune that was done and for a 383 that i built it seems to flat at spots. Just wanted to know if its worth the money for the sysytem

Beater79TA

So how complete is the FAST wiring harness? I'm looking at converting a TBI car to a Procharged HSR engine and was planning on using the XFI wiring harness. Specifically, does it have all the wiring for the fans and AC controls or do I need to strip some pieces from the TBI harness to keep the AC running?

ws6transam

You are going to have to splice, one way or another. The FAST harness will get the job done, if you dont mind draping wires all over the place. However, to get the lengths perfect and out of the way, you'll need to lengthen and shorten certain wires. I have my harness going through the body where the old ECM harness used to be, then I've taped over the hole to seal it. Those A/C controls will need to be soldered into your harness I think. As for the fan control, I rolled my own sub-harnesses, but I thing FAST offers add-ons with relays that will cover your fans and automatic transmission control. Same thing with the fuel pump: I had to buy my own relay and splice it into the harness. There is going to be some cutting and splicing that you'll need to do. This isn't 100% plug and play. However, I did manage to convert my car from Gen6 DFI to FAST XFI in only about six hours.