speedo calib.
- Thread starter fatboy1
- Start date
Is it just the speedo or is the odometer out of whack too?
If its just the speedo your options are limited as any changes will affect the odometer and how the engine ECM see's the world.
If they are both out, the likely culprit is an improperly set "Tire RPM" in the engine ECM. The difference between new tires and old and between different brands and tread patterns of the same size can be quite staggering (there's a pun for you racing gearheads!).
Check it against a GPS or over a period of 25-50 miles against the mile markers on the road and see where you are at.
And if it is your speedo only, even brand new ones off the shelf can be out 2-4 MPH, its a proplem more expensive to fix than it's worth in that case.
If its just the speedo your options are limited as any changes will affect the odometer and how the engine ECM see's the world.
If they are both out, the likely culprit is an improperly set "Tire RPM" in the engine ECM. The difference between new tires and old and between different brands and tread patterns of the same size can be quite staggering (there's a pun for you racing gearheads!).
Check it against a GPS or over a period of 25-50 miles against the mile markers on the road and see where you are at.
And if it is your speedo only, even brand new ones off the shelf can be out 2-4 MPH, its a proplem more expensive to fix than it's worth in that case.
Sorry to butt in on this line, but I don't know how to start a new thread and we need a question answered if anyone knows where to find it.
Does anyone know where to find information on the Mercedes Benz OM 926 LA 330HP
We found general info but nothing about dependability, any long term maintenance problems Thanks
Does anyone know where to find information on the Mercedes Benz OM 926 LA 330HP
We found general info but nothing about dependability, any long term maintenance problems Thanks
nightcreacher
Veteran Expediter
Your speedometer was set with brand new tires,as the tires wear, you mph will become slower than the speedometer shows.Taking to a shop and having recalibrated is more trouble than its worth.
greg334
Veteran Expediter
Night, it is the opposite, the tires wear, they get smaller and run faster - the MPH on the speedometer increases.
I'll have to agree with piper as to the differences in tires etc. One of my buggies the speedo is out 3mph but the odo is about bang on. So if I recalibrate for the speedo then my miles travelled will be lower (that's good isn't it?). I tried a different brand and deep tread design and it definitely brought the speedo more in line with reality even thoguh they were same size as originals. Unfortunately they caused problems for the esp system and I had to replace them with something less aggressive.
Nightcrawler most factories do setup for new tires but usually one brand and tread design. As most trucks have different ones due to different requirements it is quite possible to have a new truck with tires of a different rolling radius than the original specs thereby throwing the speedo out of whack a couple of mph.
Rob
Nightcrawler most factories do setup for new tires but usually one brand and tread design. As most trucks have different ones due to different requirements it is quite possible to have a new truck with tires of a different rolling radius than the original specs thereby throwing the speedo out of whack a couple of mph.
Rob
bluejaybee
Veteran Expediter
I would say that you have found a good reason to purchase a GPS if you don't already have one. It would be cheaper than the fix. A GPS would let you know exactly how much your speedo is off and will always be there to back up the milage or speed. My speedo is only off 1 mph at 60, so I know which way to adjust my speed when it is important.