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Thread: 2011 5.3 Silverado Cannot get speedo to match ecm speed readout.

  1. #1
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    Question 2011 5.3 Silverado Cannot get speedo to match ecm speed readout.

    No matter what I do I cannot get my ecm to match my speedometer. When I bought the truck the speedometer read 3 mph slow at 60 mph. This was with bone stock 265/70r17 tires 31.6" tall. In order to correct the speedo I had to enter 32.31" tire; VSS Tire Revs per > Dist = 388, Dist - Trans = 624.22. Speedo read correct but now I am off 6 mph according to hptuners scanner mph which is about 10%. The problem is this screws up all my shifts, they all occur 10% early. I just installed 33" tires and in order to correct the speedo I had to enter 34.65" tall tire. I've tried messing with the Dist - Trans numbers and it does not change a thing.

    What do I need to change to align my ecm speedo shift mphs while having my speedo read accurate? Is this possible, what the hell is going on?
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    Last edited by Nitroused383; 03-21-2016 at 06:57 AM. Reason: Added tune
    2000 Camaro SS M6
    11:1 Stock bottom end
    76mm Altitude compensator

  2. #2
    Tuning Addict 5FDP's Avatar
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    Your gear/tire wizard still says you are running a 30.87in tire. I would change that and hit auto scale to fix your issue.

    It's all I've had to do on most of the new trucks to correct any changes.
    2016 Silverado CCSB 5.3/6L80e, not as slow but still heavy.

    If you don't post your tune and logs when you have questions you aren't helping yourself.

  3. #3
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    Its not that simple at all I've tried that many times. I have it manually scaled in that tune but if you use the wizard I have to input 34.65 to get my speedo to match. That doesn't solve the issue of the ecm reading 10% high.
    2000 Camaro SS M6
    11:1 Stock bottom end
    76mm Altitude compensator

  4. #4
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    Further investigation results. Speedo reads correct via multiple gps units.

    Speedo=10 Scanner=13 First gear shift should occur at 11 mph but its happening at 8mph.
    Speedo=30 Scanner=33
    Speedo=55 Scanner=58
    Speedo=60 Scanner=64
    Speedo=70 Scanner=74-75

    So how is this even possible? Is my needle position just off on my speedometer, is there some sort of settings in the BCM i cannot access? Does hptuners 2.24.982 have a bug with my operating system not allowing the VSS Tire revs per distance - trans table to make any difference in the ECM MPH? I have tuned tons of cars / trucks and have never ran across this issue before. My truck came from Canada but has a US standard gauge cluster, you can change the digital displays to miles or kilometers so I'm not sure there is actually a difference between the US and Canadian trucks. Any help is appreciated.
    2000 Camaro SS M6
    11:1 Stock bottom end
    76mm Altitude compensator

  5. #5
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    So I've found the issue. Who ever installed the standard gauge cluster they did not reset the needle position to 0, it reads slightly below (3 mph-ish). Looks like I will be taking the gauge cluster apart, man something as simple as this I really racked my brain over
    2000 Camaro SS M6
    11:1 Stock bottom end
    76mm Altitude compensator