I've got a 1993 Z28 (original owner, one of the very 1st 4th gens sold in the Northern VA area) and about 11 years ago I replaced the engine with a 383 LT1 short block, LT4 cam, hi-ratio rockers, headers and used the factory heads (upgraded springs) and factory intake. I could never get the O2 sensor to be "read" by the ECM and have tried replacing the ECM and many different types of O2 sensors (heated and non-heated). I gave up on it and recently decided I want to re-engage this project...

I heard the FAST XFI system is a good whole swap for me to do... I wanted some input, suggestions or feedback on this from others who have used it on a 4th Gen F-Body. I'm looking for how easy it was to tune, issues/concerns with it, performance expectations, or any other general info.

Thanks!

 

This doesn't answer your question specifically, but I asked the same question a couple of years ago:

FAST XFI ecu on our cars? - CamaroZ28.Com Message Board

Maybe this will get you started.

As mentioned in the responses, tech at FAST would probably be your best bet. From what I understand, running an aftermarket ECU does not account for running your factory dash gauges. As far as tunability, the FAST would be a huge improvement over the factory ECU. Maybe someone with actual experience will chime in. I'll be interested to see what you come up with.

Edit: I would also talk to EFIconnections.com. This would allow you to get rid of the optispark, go to coil on plug and run the LS1 PCM, if the technology is available for the 93 LT1. I know they can do 94 and later.

 

The tach (94 and up) and speedo get signals from the stock PCM. The volts, coolant temp, oil pressure, and fuel level come from independent sensors, not the PCM. The FAST should produce an RPM signal if needed. But the 93 tach is driven off the coil.. Just leave the stock PCM in place to drive the speedo. My MoTeC ECU install in 2000 was handled that way.

Looking at the post you linked, I don’t know how I missed it, but the data from the Opti includes both crank and cam position. My MoTeC ECU used that info for ignition timing and sequential fuel injection. I suspect FAST might have considered that approach. While it wasn't essential that I install 8 LS1 coils, the MoTeC offered an optional 8-channel ignition driver to manage the 8 coils. And as noted, all that was done 20+ years ago. Removing the high voltage function from the Opti seemed to extend the life of the Mitsubishi optical module in the Opti. Even the low $$$ Bailey Engineering LTCC can use the Opti signals to fire 8 independent LS1 coils.

Just to clarify the availability of the crank position data coming from a sensor driven by the cam, it takes two revs of the crank to fire all 8 cylinders. The cam rotates once for each two crank revs. The inner circle of slots/windows (low resolution pulses) is coded by variable window width slots representing four of the cylinders, alternating with fixed width slots for the other four cylinders. The ECM recognizes which cylinder is approaching TDC on the compression stroke based on the variable widths of the alternating windows. Some aftermarket ECU's can be programmed to recognize the cylinder signals from the Opti.

I'm more interested in why the ECM was unable to “read” the O2 sensor (one or both sensors?). First time I’ve seen that problem in the 25 years I've been helping LT1 owners on multiple sites like this.