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VSS Changes going from M6 to TH400?

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Old May 25, 2007 | 07:52 AM
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Default VSS Changes going from M6 to TH400?

I did some digging around through the search and most say to just get the correct part number. That isn't an option now since the tranny is in an done. I guess my issue was the reluctor ring is now a 40 teeth vs. the original which was 17 teeth or visa-versa. Apparently the speedo things your doing 130 when you are really doing like 45-50.

I have LS1 Edit and looked into the tables. It looks like there is a VSS pulse number in the tables that is currently set to 4000.

If you just divinde out the teeth count 40 / 17 it comes out to 2.35 times larger. Can I just multiply that Pulse count 4000 * 2.35 so the speedo reads the correct mph?

If my math is correct and that method is correct my value would now need to be at 9,400 pulses.

(mods, wasn't sure if this was a PCM topic or a Tranny topic or both)

Can someone confirm or correct my logic?
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Old May 25, 2007 | 11:00 AM
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Changing the 4000 number will probably only correct your speedometer reading, but your PCM will still think you are going faster then you really are.

The 4000 number refers to the number of pulses the speedometer expects to get. There should be another value called "pulse per mile" that you can apply your formula to that would correct for the difference in teeth on the reluctor (17 = Manual, 40 = Automatic).
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Old May 25, 2007 | 08:06 PM
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Anyone got a formula and has done this before? I don't want to botch it up.
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Old May 29, 2007 | 06:10 PM
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so I have to change the PPM and the pulses? I'm not sure there is just an entry for pulse count via edit.
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Old May 29, 2007 | 06:21 PM
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Just email me the ls1 file, i will modify it to be 40ppr, i will need the rear end gear and tire size also
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Old May 30, 2007 | 12:04 AM
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I sent you an email. I believe I remember you from over on ls1tuning.
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Old May 31, 2007 | 08:59 PM
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so did it work?
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Old May 31, 2007 | 09:52 PM
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wait4me, I am sorry that I didn't realize what you were planning on doing. I thought you were going to do a simple parameter change that I could look at and then just make the change to my actual file. The edit file I sent to you is not my most current tune as my last one was done by a guy with his own software during a dyno session. I have not taken a new full read yet so anything I upload will blow away my $$$ spent on the dyno tuning.

Is there any chance that if I take a full read so I have all of the latest wot/spark/fuel changes that you could re-do your magic? I felt like an *** after you told me what you had done and that I couldn't just copy-paste the change.

Let me know.
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Old Jun 4, 2007 | 12:57 PM
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So my guess is that when you change from the M6 to A4 or vice versa that it is using a different parameter in the LS1Edit file to state the number of teeth on the reluctor for the VSS (17 vs. 40)

Because there is no screen for me to just change the # teeth on the tranny I assume that is why people are saying to flash an auto file and then just delete the codes etc.

If I can't get Wait4Me's changes made can I just leave it as a manual file and make the tire size huge to accomodate the # of teeth? When I switch from M6 to A4 it looks like it reads a tire circumference of 58.5 inches or something like that from my 25.8 in the M6 file.

I wish I could just change the #-Teeth parameter and be done which I have a feeling wait4me was able to do.
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