MPH on scanmaster Wrong
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Jerryl
Tall Unvaccinated Chinese Guy
- Joined
- Dec 14, 2004
- Messages
- 9,643
Scanmaster reads 42mph at 75mph is this a big problem or not.
it starts out right on but at about 19mph it loses mph's
It can be a problem.
The chip calculates the fuel requirements based on a few factors, one of them is MPH. You want to be within 5.
Question is "why" the error is not constant.
- Joined
- Aug 1, 2003
- Messages
- 9,760
ecm uses the speedo for certain functions so you want the reading to be close to actual , that big a reading error is usually found on the older 145speedometers that used an inline speedometer adapter , that adapter ruduces the speed of the cable and that causes the ecm to get the wrong speed
if you have the 145 speedo and you want the speed to read correctly you'll need to ditch the adapter and get the speedometer sent out for calibration. kirbans 145 speedos are recalibrated and he may be able to help.
if no 145 speed and no adapter than the VSS buffer is defective or on a long shot the VSS optic bar in the speedometer cluster is not reflecting . the VSS neeeds to see two signals for each revolution of speedo cable to determine speed , the optic bar is at the end of the cable (part of speedometer head ) and an optical sensor reads the reflection off that bar and the VSS buffer converts it to a signal the ecm can read .
if you have the 145 speedo and you want the speed to read correctly you'll need to ditch the adapter and get the speedometer sent out for calibration. kirbans 145 speedos are recalibrated and he may be able to help.
if no 145 speed and no adapter than the VSS buffer is defective or on a long shot the VSS optic bar in the speedometer cluster is not reflecting . the VSS neeeds to see two signals for each revolution of speedo cable to determine speed , the optic bar is at the end of the cable (part of speedometer head ) and an optical sensor reads the reflection off that bar and the VSS buffer converts it to a signal the ecm can read .
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