Attention: TDR Forum Junkies 
I recently completed a Cummins diesel conversion on my truck, and something odd has been happening with my speedometer. When I’m driving on the highway and keeping pace with traffic, the speedometer shows about 10 mph higher than I think I’m actually going. It’s frustrating because I rely on accurate readings, and I’m not sure what’s causing this discrepancy.
I used a tool to recalibrate the speedometer after the conversion, and it seemed to work initially. However, now I’m questioning whether I missed a key step in the process or if the tool isn’t fully compatible with my setup. The conversion involved replacing the engine, but I didn’t change the gear ratios or tire sizes, so I’m unsure if those factors could still be affecting the readings. Could the diesel engine’s torque and RPM characteristics be causing this? I’d appreciate any insights from those with experience.
A speedometer measures and displays the vehicle's speed using data from sensors connected to the transmission or wheels. It translates rotational speed into a readable format, typically in miles or kilometers per hour. Some speedometers even include instantaneous speed tracking online, which can provide precise, real-time monitoring. This makes me wonder if there’s something about the way the tool interacts with my diesel setup that I didn’t account for during calibration.
Has anyone else experienced this kind of issue? If you’ve done a similar swap, did your speedometer work correctly afterward, or did you have to make specific adjustments? What steps did you take to ensure accuracy? I’d also like to know if there’s something I should revisit, like checking the tool’s settings or redoing the calibration entirely.
I’d appreciate hearing your thoughts and experiences with similar conversions and speedometer recalibrations. What worked for you? Are there specific troubleshooting steps I should try? Let me know if you’ve faced this before and how you resolved it!
I used a tool to recalibrate the speedometer after the conversion, and it seemed to work initially. However, now I’m questioning whether I missed a key step in the process or if the tool isn’t fully compatible with my setup. The conversion involved replacing the engine, but I didn’t change the gear ratios or tire sizes, so I’m unsure if those factors could still be affecting the readings. Could the diesel engine’s torque and RPM characteristics be causing this? I’d appreciate any insights from those with experience.
A speedometer measures and displays the vehicle's speed using data from sensors connected to the transmission or wheels. It translates rotational speed into a readable format, typically in miles or kilometers per hour. Some speedometers even include instantaneous speed tracking online, which can provide precise, real-time monitoring. This makes me wonder if there’s something about the way the tool interacts with my diesel setup that I didn’t account for during calibration.
Has anyone else experienced this kind of issue? If you’ve done a similar swap, did your speedometer work correctly afterward, or did you have to make specific adjustments? What steps did you take to ensure accuracy? I’d also like to know if there’s something I should revisit, like checking the tool’s settings or redoing the calibration entirely.
I’d appreciate hearing your thoughts and experiences with similar conversions and speedometer recalibrations. What worked for you? Are there specific troubleshooting steps I should try? Let me know if you’ve faced this before and how you resolved it!
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