HPTuner reading 0mph at speed
10-13-2010, 09:18 PM
#1
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HPTuner reading 0mph at speed A friend of mine is a local GM computer calibrator using HPTuner. As we were driving he stated that while we were at speed the GM ECU was seeing a speed of 0 MPH. The tach was matching the dash display. Has anyone had this same experience on a LS2 conversion car?
I relocated the IAT & intake to match what FM is doing with their NBs thinking that getting the IAT away from the radiator would help increase mpg. No luck, so far, still ~12mpg in town. We're going to Surf 'n Safari in the morning, so will get to see if it's still ~24mpg at speed.
I relocated the IAT & intake to match what FM is doing with their NBs thinking that getting the IAT away from the radiator would help increase mpg. No luck, so far, still ~12mpg in town. We're going to Surf 'n Safari in the morning, so will get to see if it's still ~24mpg at speed.
10-13-2010, 11:17 PM
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Yes, although instead of going through the ECU it's going through a little black box to talk with the Miata Speedo.
Is it going to be the case that I'll need to run a 2nd line from the VSS to the ECU? Will the two outputs have any undesirable effects on each other?
Is it going to be the case that I'll need to run a 2nd line from the VSS to the ECU? Will the two outputs have any undesirable effects on each other?
10-14-2010, 01:23 AM
#4
On a standard install, the vss sends a 17 (auto) or 50 pulse per revolution (6 speed) to the computer. The computer converts this to about 120k ppm and sends this signal to the speedo.
Guessing your "little black box" converts the signal down to a more generic 8k ppm used on a lot of aftermarket speedos, so the computer is reading a very slow speed.
You generally need the vss signal to prevent stalling issues, but it doesn't need to be accurate for that. The only other reason you might want an accurate speed signal is for using the GM DBW cruise control.
Guessing your "little black box" converts the signal down to a more generic 8k ppm used on a lot of aftermarket speedos, so the computer is reading a very slow speed.
You generally need the vss signal to prevent stalling issues, but it doesn't need to be accurate for that. The only other reason you might want an accurate speed signal is for using the GM DBW cruise control.
10-14-2010, 10:53 AM
#5
On a standard install, the vss sends a 17 (auto) or 50 pulse per revolution (6 speed) to the computer. The computer converts this to about 120k ppm and sends this signal to the speedo.
Guessing your "little black box" converts the signal down to a more generic 8k ppm used on a lot of aftermarket speedos, so the computer is reading a very slow speed.
You generally need the vss signal to prevent stalling issues, but it doesn't need to be accurate for that. The only other reason you might want an accurate speed signal is for using the GM DBW cruise control.
Guessing your "little black box" converts the signal down to a more generic 8k ppm used on a lot of aftermarket speedos, so the computer is reading a very slow speed.
You generally need the vss signal to prevent stalling issues, but it doesn't need to be accurate for that. The only other reason you might want an accurate speed signal is for using the GM DBW cruise control.
10-14-2010, 10:55 AM
#6
Yes, although instead of going through the ECU it's going through a little black box to talk with the Miata Speedo.
Is it going to be the case that I'll need to run a 2nd line from the VSS to the ECU? Will the two outputs have any undesirable effects on each other?
Is it going to be the case that I'll need to run a 2nd line from the VSS to the ECU? Will the two outputs have any undesirable effects on each other?
The Dakota Digital box doesn't have a "pass through" output for the original computer as well?
If not, you can probably split the signal, but I don't know what kind of signal degradation you'd see...or you could adapt a wheel speed sensor or something else...the actual pulses per mile from the sensor doesn't REALLY matter, so long as you can calculate how many there are, and flash that into the PCM so that any MPH based tables reflect an actual vehicle speed.
