Results 1 to 5 of 5

Thread: why can't I get my speedometer accurate?

  1. #1
    Junior Member
    Join Date
    May 2012
    Posts
    42

    Default why can't I get my speedometer accurate?

    I've been battling this thing for weeks.

    Adjusting revs per mile in the TCM, pulses in the ECM.

    No matter what I'm out 15% to the low.

    It's a 3.73 gear truck with 325/60R20 Nitto Terra Grapplers

  2. #2
    Lifetime Member tokymon's Avatar
    Join Date
    Apr 2008
    Posts
    227

    Default

    i just adjust in the ecm and messure the tires and put that in not what the tire calc says. (ie. tires= 35x12.5x16 but messure only 34.5 tall)
    97 2500 ecsb 5.7l/4l80e/4x4 411 pcm /thorley tri-y's/dual super 40's with x (catless)/aem cai/msd 6a and coil/zz4 cam/beehive spring/lm-1

    stock sucks

  3. #3
    Lifetime Member
    Join Date
    Jul 2012
    Posts
    289

    Default

    Post up the tune and ill look at it later tonight
    14 GMC Sierra
    5.3L CC SB 4x4
    Basic tuning....

  4. #4
    Lifetime Member minytrker's Avatar
    Join Date
    Jan 2006
    Posts
    1,308

    Default

    Quote Originally Posted by tokymon View Post
    i just adjust in the ecm and messure the tires and put that in not what the tire calc says. (ie. tires= 35x12.5x16 but messure only 34.5 tall)
    THats the trick, almost every all terrain or mud tire I have measured was always off. All the low profile 22's, 24's, etc are usually dead on though.
    99 Z28 Camaro|LS1 Heads & cam Tuned by LSX Power Tuning
    2003 CC Duramax Dually|19.5 w/245/70/19.5|Tuned by LSX Power Tuning|5in exhaust
    2009 G8 GT Vararam CAI|Tuned by LSX Power Tuning|GXP Mufflers|Custom System
    2006 CTS-V K&N CAI|OBX Headers|Cammed LS3|Tuned by LSX Power Tuning|

  5. #5
    Lifetime Member THEFERMANATOR's Avatar
    Join Date
    Mar 2009
    Posts
    790

    Default

    DON'T CHANGE THE TCM, LEAVE IT ALONE! All you are doing by changing the TCM is changing your shift points and throwing your adapts off. The factory calibration is set up and should work pretty well with most combos regarding of gearing. Only make changes to the ECM for speedo changes. If you know your actual speed VS displayed speed, go into the speedo calculator select speedo fine tuning, and put in the numbers. This will get it pretty dang close.
    1995 GMC 2500 SUBURBAN powered by 01 DURAMAX/ALLISON, little of this, a little of that,
    DIAMONDEYE 4" exhaust, CORSA muffler, AFE stage 1 dry filter, custom tuning by me, KENNEDY single pump and pump rub kit.

Similar Threads

  1. How accurate is Auto VE?
    By GMCtrk in forum Gen III V8 Specific
    Replies: 56
    Last Post: April 9th, 2010, 01:02 PM
  2. How accurate is the AFR?
    By SSThunder in forum General (Petrol, Gas, Ethanol)
    Replies: 11
    Last Post: August 6th, 2007, 02:55 PM
  3. Which one is accurate?
    By zapp168 in forum General
    Replies: 4
    Last Post: July 25th, 2007, 12:41 AM
  4. Accurate pricing
    By eboggs_jkvl in forum Lounge
    Replies: 4
    Last Post: December 6th, 2006, 03:55 AM
  5. How accurate is the HP calc?
    By dbaxter_ss in forum General (Petrol, Gas, Ethanol)
    Replies: 3
    Last Post: February 20th, 2005, 02:48 PM

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •