I think my PCM values have gotten corrupted ... could someone please
post the factory values for a 95 with the 3:42 rear

Speedometer Scalar = ?
Speedometer Scalar, Fraction = ?
Speedometer Scalar, (Scan Tool) = ?
Speed Pulses per Driveshaft Revolution = ?
Time Between Pulses For 'Stop' = ?

thank you

 

I show:

Speedometer Scalar = 12
Speedometer Scalar, Fraction = .984
Speedometer Scalar, (Scan Tool) = 45.85
Speed Pulses per Driveshaft Revolution = 17
Time Between Pulses For 'Stop' = 76.233

 

94ZRagtop:

Thanks for the reply ... for some unexplained reason mine is

Speedometer Scalar = 11
Speedometer Scalar, Fraction = 1.078
Speedometer Scalar, (Scan Tool) = 45.849
Speed Pulses per Driveshaft Revolution = 17.00
Time Between Pulses For 'Stop' = 77.04

Comparing highway mile markers against the odometer was telling me something wasn't right.

 

Yeah, the scalars can be kind of funky. Yours are pretty close.

Tunercat has a function where it can calculate scalars based on tire size, gear ratio, and transmission pulses per revolution. I stuck the standard values in there, and they were not *exactly* the same values that I posted. For example, with stock 245/50/16 tires, I get

12, 1.019, 46.17, 17, and 74.25

Just changing the tire to a 295 50 15 (slightly taller) yields

11, .969, 44.517, 17, and 81.

So you can see just tweaking the tire size a little can change the values, but they'll be "pretty close". I assume you or someone reset the tire size at one time.

 

I don't remember changing anything because there's a tire/wheel faq on the forum that says my current tire size is essentially the same diameter as the original 16s with the factory GSCs. I've been the only owner but somewhere I must have changed values (perhaps toying with the recal option in TunerCAT) then changed something else and saved the tune while forgetting I'd been in the speedo recal. Again, thanks.