Obd2 speed doesn't match
Thread Starter
Staging Lane
Joined: Jan 2014
Posts: 53
Likes: 0
From: Blacksburg, VA
Obd2 speed doesn't match The guy tuning my car ran into an interesting situation today. He said when checking the speed through the OBD2 port it showed twice what it should have. The speedometer is showing the correct speed and the transmission is shifting correctly.
The car is a 1984 Corvette with a 2001 Corvette LS6 motor and a 1999 Camaro 4l60e transmission
Any ideas what parameters he should check?
The car is a 1984 Corvette with a 2001 Corvette LS6 motor and a 1999 Camaro 4l60e transmission
Any ideas what parameters he should check?
Thread Starter
Staging Lane
Joined: Jan 2014
Posts: 53
Likes: 0
From: Blacksburg, VA
The speedometer is driven from the speedometer output of the ECM and goes through a Dakota digital box to calibrate the 1984 Corvette Digital speedo.
The speedo and the transmission shifting are accurate, it's the obd2 output that looks exactly double of what's on speedo.
The speedo and the transmission shifting are accurate, it's the obd2 output that looks exactly double of what's on speedo.
On engine swap vehicles I always set up the speedometer in the pcm and get it reading correctly (correct tire size and gear ratio) and verify it with gps. Once the speedometer is correct in the computer then I worry about the gauge in the car since 99% of them have to be programmed also.
Teching In
Joined: Apr 2006
Posts: 3
Likes: 0
On engine swap vehicles I always set up the speedometer in the pcm and get it reading correctly (correct tire size and gear ratio) and verify it with gps. Once the speedometer is correct in the computer then I worry about the gauge in the car since 99% of them have to be programmed also.
The Stack speedometer is expecting to see about 35,333 pulse per mile, based on the OEM tire size of 225/45-16 with a 42 tooth wheel.
