Need some insight on VSS Tuning

I cant seem to figure out why my speedo isnt working right. I've played with many variable combinations, and for some combos I get a max speed reading of 5. I'm sure I'm missing something but I cant seem to figure out what.

2005 SS/SC paired with a F23 from an HHR.
FD: 4.17
Tires: 225/40R18
Speed ring teeth: 29

So with the above info I should have the following numbers correct:
FD = 4.17
VSS Tire Revs Per Mile = 822.88 (rounded)
Pulses per =23863 (rounded)

With the following set in HPT, I am not getting the right response at all from both the Speedo or the software. So I initially thought it was the VSS on the trans, so I switched that puppy out and no dice, same numbers appear.

Is there anything else I could be missing here?

Note: I do not get the same RPM values for every combination. in fact this tune now gives me the lowes values. The base tune had gotten me to at least 5 RPM. Also, no other information was changed outside of these settings.
 

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Gtstorey

Goblin Guru
I don’t think that FD is correct. The stock tunes that I have checked show it to be 1:1 which makes since for final drive of overdrive. I just realized that I had mine set to the gear ratio like you had this last weekend. But mine has been reporting the correct speed in HPT so I don’t know that is your only problem.
 

ctuinstra

Goblin Guru
This is what I have on our 07 SS/SC. My FD is also 1:1 and the error is the transmission ratio is 3.05 which is what's on the plate. It's doesn't make sense after reading the tips on each selection.


37274
 
I may have something wrong that’s not the numbers. Not not sure that out could be. For now I’ll just have to use a gps speedometer.
 

ctuinstra

Goblin Guru
I may have something wrong that’s not the numbers. Not not sure that out could be. For now I’ll just have to use a gps speedometer.
Have you tried putting the FD ratio to 1:1? There are two of us that are stating it's a working setup. I did not change the number, that is stock on our car and the speedo works fine.
 

baustin

Well-Known Member
For my 06 SS/SC, with stock F35 setup. I also use a final drive ratio of 1:1. I see your (@Forceofaqua) screenshot only shows the 'basic' layout. The 'advanced' layout is required to set the VSS pulses per rev field. I was the one that adjusted these speedo fields for my car and my speedo is right on my GPS speed with my Goblin tires.

37293


Changing to 'advanced' view:
37294
 

Rauq

Goblin Guru
2006 LSJ with an F23, 225/45R17 tires. The gear ratio of your trans shouldn't matter for the VSS Pulses Per Rev setting (I have the 3.84 F23), the sensor's just measuring the speed of the diff housing which is the same as your axle shaft speed and your wheel speed.

Tire size

37297
 
Got it! it was in fact the hardware setting. I didnt know there was an advanced view, so I really appreciate it everyone. Also I did set the FD back to 1. Hope this helps others out.
 
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