I've been looking through the FSM & body electrical troubleshooting manuals to try to find specs on the speedo sensor mounted on the transmission (manual in my case) and had no luck. Was wondering if anyone had a calibration spec on it, i.e., # of pulses or frequency out vs. RPM input of the speed sensor shaft?

My FD speedometer works just fine, and is pretty accurate when tested against the GPS speed displayed in Google Maps. Anyway, after finishing up the rewire project on my FD, I'm trying to get my Link G4+ Fury ECU to support cruise control with my GM DBW throttle. So I wired the factory speedo sensor to a digital input on the Link to provide the vehicle speed input signal. Everything is good to go hardware wise, but the calibration for the speedo sensor that the Link is using is way off. For example, if I drive along at a steady 40MPH, the Link will be logging a driven wheel speed of around 150MPH.

I suppose I could derive the calibration by a test drive and some reverse engineering of the logs - drive at a constant speed and log driven wheel speed on the Link, rinse & repeat at different constant speeds until I can build a decent calibration curve. But if there's a published spec for the sensor out there, I'll save some gas in test drives

 

The speed sensor in the transmission goes to the dashboard, and then the dashboard converts that to a digital signal that the ECU uses for measuring speed. On my ECU, the calibration option is a multiplier for converting raw frequency into MPH. For my car with stock-size tires that multiplier is about 1.0 , so 60Hz raw frequency from the dashboard calculates to 60MPH measured by the ECU. The numbers looked pretty close the last time I compared the GPS speed from my phone's navigation app.

 

^My Link ECU is looking for the same thing - a simple multiplication factor. The PO (who didn't use this function) left a figure of 220 in there, which may explain why the driven wheel speeds the Link is logging are so much higher that actual road speeds! Can't hurt to try the same 1.0 multiplier you're using, I'll give that a shot and see what the logs tell me.

 

An update - I tried the 1.0 figure Scott posted which worked for his different ECU; result with my Link G4+ was it displayed supersonic speeds backing out of the driveway! But that was useful because it indicated which direction to adjust the number. Since the old 220 figure had it reading roughly double the actual road speed, and I now knew I needed a higher #, so I changed it to 440. That is almost spot on - actual road speed is within a couple of MPHs of the indicated speed on the PCLink tuning software. As I'm not using the Link to drive the OEM speedo or a digital dash, and only using the speed input to support cruise control, that's good enough.

Bottom line, I now have cruise control functionality via DBW throttle using the FD's OEM switch gear rewired and managed by the Link G4+ ECU! I still need to tune the cruise control PID settings in the Link as the defaults result in a herky-jerky cruise behavior with my GM DBW throttle, but it works!

 

Glad it's sorted. How is the idle and tip-in throttle response with the GM DBW throttle? Part of me likes the idea, but I'm also concerned how the engine will behave at light loads if feeding air to the primary and secondary intake ports.

 

I had the same concerns about idle & tip in before I purchased the car as it came from the PO with the GM DBW, and RX8 accelerator pedal assembly, and also running a Cosmo 13B-RE upper & lower intake manifold. Even though the tune wasn't sorted out yet when I did my pre-purchase inspection, it idled well enough and the test drive convinced me that drive-ability was good enough that I'd be able to improve upon it with some tuning.

Fortunately I've found out that the Link G4+ is a great ECU, and their user support is top notch - enabled me to quickly climb the learning curve and get productive tuning the thing. It now idles smooth under all conditions, to include cold & hot starts, warm up cycle and transient loads like when the fans or P/S kicks in. A/C isn't restored yet, but I suspect that won't be an issue either. Motor has stock ports, so it will happily idle at 900RPM when warm. I was also able to tune out the tendency where it wanted to stall when abruptly decelerating and coming to a stop in neutral - that was just a matter of dialing in some of the e-throttle's synthetic "dash pot" settings.

As for throttle tip-in, I'm still working on smoothing that out, and have been finding it's mostly a matter of getting the accel. enrichment settings just right. Driving the car smoothly around town still requires a light & well controlled right foot, it's less analog in nature than I'd like, but it's certainly tolerable. This FD would NOT be my 1st choice for an auto cross event though! What I really need to do is get it on a dyno so I can tune the VE/fuel map under constant/controllable loads across the RPM range. I've been doing that on the road and relying on the logs & Link tuning software, but that can be a slow and iterative process.

Another thought to improve tip-in with DBW may be to adjust how the FI's are staged - since the primary & secondary ports are always getting air with a DBW throttle, maybe it makes more sense to stage the secondaries on at lower RPMs/loads to distribute the fueling more evenly? Currently I have the primary & secondary FIs staged similar to how Mazda does - secondaries start kicking in as the load/RPMs increase; low load is pretty much all on the primaries.