Just got back from running a test on my Z, using Tunercat to do tuning. I put in a new tune that would adjust the speedo to the correct values for my tires (my car originally came with 235/55/16 and I now have 245/50/16). Well, it didn't work. My speedo mostly sat at zero but sometimes would jump around all the way up to 110. This seems odd, since you would think Tunercat would put in the correct values??? Anyone have any ideas about this one?

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DOOM Master
Jet black 94 Z28 Camaro (DOOMZ28)
Performance mods: Homemade 4" CAI, Homemade RAM Air, self ported MAF, 1996 SS exhaust, LT4 knock module, 160 thermostat, TB bypass, Pro 5.0 shifter, air silencer delete, IAT relocation, do-it-yourself custom tuning
Stereo mods: 2 Punch Power 2nd Edition 12" subwoofers, Punch 200.2 Amp, Alpine 8873 4 channel Amp, 2 Alpine Pointsource 6 1/2 speakers, 2 Alpine 6 1/2 speakers, 2 Phoenix Gold 50mm dome tweeters, Alpine head unit (8640 I believe)

 

Ild go back in and try it again....be sure to actually check the constant table values to comfirm that they were actually changed to the calculated values.

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Greg
95 Z28 conv M6
Georgia F-Body Association

Stage 1 heads, 1.6rr, Meziere WP
lt4 hot cam,lt4 timing chain kit,52mm TB,
Hooker Headers, Pro 5 shifter,3.73s,
NX 150 progressive,
Self-tuned via Tunercat

 

Oh...one more thing...make sure all the other values in the calculator are correct...dont assume that they are.

 

Yeah, I've got everything correct for the info, but I checked the original calibration values and it is quite a bit different from what Tunercat calculates. This is the original info.

speedometer scaler: (not all readable) *289*
speedometer scaler fraction: .023
speedometer scaler scantool: 45.85
time between pulses for stop 7.523
pulses per driveshaft rev: 17

This is the info that tunercat calibrates

speedometer scaler: 12
speedometer scalar fraction: 1.017
speedometer scalar scantool: 46.284
time between pulses for stop: 76.256
pulses per driveshaft rev: 17

As you can see, 3 values are way off. I wish I could read the whole speedometer scalar value

 

Ok, found out that the speedo info is also in the ECM constants (boy, should have seen that one before, guess it goes to show that I'm still new at this). The original speedometer scaler is 32896. Anyone who has more experience with Tunercat, please give me the info that would be correct for the speedo values for this info.

3.42 gears, M6, went from 235/55/16 to 245/50/16

Thanks in advance to anyone who figures this one out!

 

I'm fighiting this same problem right now!

Did you ever get the right information to put into the constants table.

If you did, I really need them.

Thanks,

D Moss

 

Why don't you just start with a Z-rated tire tune? I've got the latest calibration from GM if you want it.

 

Yeah, I accidently had it set on the EE_B def file instead of the regular EE def file. Didn't notice it, I was viewing a file from a Cadillac Fleetwood that needed to be viewed on EE_B, then forgot to switch it back. Try switching your def file to one or the other, you'll problem will go away.