Bavooz Flo

Hello,

there is a speed limiter on a GTA 1987 from california ?

Thank for your feedback

Tuned Performance

iTrader: (92)

What’s the broadcast code on the chip ?
probably set to 115mph or so

Vader

Yes. However, it is a likely impractical limit. There is a value in the factory programming for fuel cutoff at a given VSS input converted to MPH, just as there is a fuel cutoff for engine RPM. The 8-bit binary word capacity of the system allows for values from 0 to 255 to be set for parameters.

Presuming the GTA in your signature is the vehicle in question, it is common for the engine RPM fuel cutoff limit to be set above 10,000 RPM, which means that there is effectively no practical limit. Similarly, if the vehicle was originally assembled with "Z" speed rated tires, the MPH fuel cutoff limit would have been set to 255 MPH. If the original programming has been altered, there is no way of knowing what those values might be other than to read the PROM data and analyze.

Vader

I just checked a 1987 L98 binary w $32 mask from a 1987 GTA for verification. Rev limit is set to 10036.73, Speed limit is set to 255.00. I recall that some "regular" F-Bodies had MPH limits set at about 118 for other OEM tires.

Bavooz Flo

ok interesting....but other stuff, there must be a limit to kickdown in OD and 4th gear, for example I drive at 105mph and i push at wot, no kickdown ? Because I'm already going too fast ?

Vader

The transmission is not fully electronically controlled like many later designs. The only thing that is controlled in that manner is the TCC lockup/unlock. The rest is a function of balance between the governor/oil pressure, the TV cable/valve, and how those are summed at a spool in the valve body.

Tuned Performance

iTrader: (92)

Tcc unlock prevention speed threshold 75mph