Problems with Speedo Calc. / PLEASE HELP

[Boost]

Once again it's the dreaded aftermarket 4.56 gears / inaccurate speedo problem. Please help me fix this, the last time it never worked and that accounts for the only 1 out of 40 unsatisfied customers.

I'm working on a 2007 new body style Chevy Vortec Max pickup with a 6.0 liter. He has changed the factory 3.73 gears to aftermarket 4.56 ones. The speedometer is crazy as you'd expect, but fortunately the ABS light is not on, because this vehicle has 4 individual wheel speed sensors.

So I go into his speedo calculator and input his tire size and gears. The pulses per mile change, I write it, and no change in the speedo! It shows about 20 mph when you're almost at a complete stop, and about 40 mph when you're doing about 25.

Is there a glitch or some kind of trick I have to do to get this right?
PLEASE HELP ME, I NEED TO FIGURE THIS OUT ASAP. Thanks! :master:

[ChipsByAl]

What does the scan tool display? The vehicle may have a cluster issue.
Al

[Blacky]

Assuming the speedo reluctor ring is on the trans output shaft, then changing the gears from 3.73 to 4.56 will cause the pulses per mile to increase. The actual increase will be determined by the percentage increase in wheel (i.e. axle) revolutions per mile. The multiplier that you need to apply to the pulses per mile can be calculated as: new/old which is: 4.56/3.73 = 1.22252 So try multiplying your pulses per mile by 1.22252 and enter in the result as the pulses per mile. There is a calibration that defines the number of pulses per rev of the trans output shaft that is not yet exposed by EFILive (for the LS2 controller). We are adding that cal in the next release (asap). By not allowing that cal to be updated may be causing issues. Regards Paul

[Blacky]

P.S. Sorry about the formatting, something is up with either my browser or the forum... Paul

[Boost]

There is a calibration that defines the number of pulses per rev of the trans output shaft that is not yet exposed by EFILive (for the LS2 controller). We are adding that cal in the next release (asap). By not allowing that cal to be updated may be causing issues. Regards Paul

I was afraid of this.... I feel like the speedometer is looking at something else besides the pulses per mile (that I did increase from 97xxx to 115xxx).
Blacky, how soon can we get this fixed? What can I do to help?
Thanks!

[Boost]

Table H101 is 97010 VSS pulses per mile at first. When I add his tire size of 275/55/20, it drops to 94300. Finally, with the 4.56 gears it's 115284.
I made sure the main table had that value when I closed the speedo calc. window. I noticed that H0135 (tire size correction) does not change from 97010 (??).

[Boost]

The VIN # is 2GCEC13YX71507412.
OS: 12612291
Calibration: 12612290

I am looking at schematics in Service Information. Is the computer looking at various sensors and comapring what is sees, then possibly still going with what makes sense based on engine rpm or something possibly? :help2:

[Boost]

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[Boost]

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[Boost]

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[Boost]

"When attempting to change tire size, it is important to understand what tire size the customer is interested in installing. General Motors will ONLY support a tire calibration for tires that have been sized, tested and designed for the vehicle in question and its applications. DO NOT use the information offered in the ABS module (tire size selection) as a guide to see what tires are applicable to the vehicle in question. Keep in mind, changing the tire size in the ABS module will only affect ABS wheel speed sensor calibration that are direct inputs to the ABS module. It will not correct or calibrate the speedometer's accuracy, and will not change the calibration of the ABS rear speed sensor value on vehicles that obtain rear wheel speed data from the ECM/PCM/VCM via the VSS."

[Boost]

Bump - Well, so what is it? A second table that will be uncovered in the new update coming soon? Help me out here pweeese

[Blacky]

There is a calibration that defines the number of pulses per rev of the trans output shaft that is not yet exposed by EFILive (for the LS2 controller). We are adding that cal in the next release (asap). By not allowing that cal to be updated may be causing issues. Regards Paul

By not having that cal defined (and therefor available to be used/set in the EFILive software), the speedo calculator is not able to correctly calculate the various settings.

That is why I explained how to do it manually.

The cal will be available in the next release and that should help to correct some speedo calculator problems.

Regards
Paul

[Boost]

I'm sorry Paul, in all my excitement I must have missed where you explained it. It would be REALLY great if I could make it work manually for now. Which table is it? Because in my previous post in this thread, I said that the value in H0101 DID change to a number that made sense, but had no effect on the speedo.

Please run me through what exact table has to be changed manually. Thanks a lot! It's really not a big deal if the speedo calculator is acting up right now. The more I learn about this the more I realize how hard it is for you guys to keep up with all of GM's software CRAP. (some of which is insane)
You're doing a great job!

[Boost]

Assuming the speedo reluctor ring is on the trans output shaft, then changing the gears from 3.73 to 4.56 will cause the pulses per mile to increase. The actual increase will be determined by the percentage increase in wheel (i.e. axle) revolutions per mile. The multiplier that you need to apply to the pulses per mile can be calculated as: new/old which is: 4.56/3.73 = 1.22252 So try multiplying your pulses per mile by 1.22252 and enter in the result as the pulses per mile.


Table H101 is 97010 VSS pulses per mile at first. When I add his tire size of 275/55/20, it drops to 94300. Finally, with the 4.56 gears it's 115284.
I made sure the main table had that value when I closed the speedo calc. window. I noticed that H0135 (tire size correction) does not change from 97010 (??).

94300 x 1.22252 = 115284

This value was in the tune, I saved and flashed it. On the test drive, the speedo was still acting exactly the same as before. What else can I do manually to correct it? Thank you for your time!

[Boost]

:help: :nixweiss:

[Blacky]

Post me the tune file to paul@efilive.com.
I'll take a look, maybe I'm overlooking something.

Regards
Paul

[Boost]

E-mail sent.

[Blacky]

Got it, I've sent a relpy of a number of things to try, let me know which option helps. Then I can post up the succesful method here.

Regards
Paul

[Boost]

Thanks, that gives me a couple of options to try. I will try to fugure out which one worked and why, and post the results in the end. I appreciate it.

[Boost]

:cheers: SUCCESS! Thanks to Paul's help, the speedo reads perfect now. At first I tried changing just H0135 (in addition to H0101 that was already changed before). This alone did not fix it, as we were showing 40 mph when actual speed was 32 mph. Then I flashed it with "plan B", in which I adjusted H0103 and H0122. I also changed H0103 in the tranny cal. This worked! We are now showing the right speed, it's perfect. Thanks so much for helping me fix this!

So the culprit was H0103 and / or H0122. Thanks !!! :master:

[lb7diesel]

Can someone elaborate more on what to change to correct the speedo. My dad just put 3.90 gears in his silverado. I also used the speedo calculator to correct the speed. I entered the new gear ratio along with his tire size. I entered every new H # into the proper table and then saved. Nothing is correct still. It did stop the ABS light from coming on though..

I was going to try and divide 3.90/3.42 and then multiply that into the factory setting like Paul said, but I see that there is more to change. What else do I need to change?

[Boost]

Did you change H0103 in the TRANNY cal? I posted everything I changed that helped me, good luck!