Speed logging error

[Jeremy Towers]

Hi

I am having an issue logging vehicle speed above 180kph (Log file attached)

I have a Link G4 Xtreme picking up vehicle speed from an electronic sensor in my T56 Tremec gearbox. During drag runs my car exceeds 180kph but my logging won't show any speed above 180kph. Given that the speed it fails is always exactly 180kph I suspect it is a software or setup issue.

I just noticed that my speed limit (although disabled) has an rpm setting of 180kph. That might be a red herring though.

Any thoughts on how to fix this?

Thanks, Jeremy

drag2.llg

[Scott]

Hi Jeremy,

I have looked at your log file. I can see where the speed is falling over, and at the same point the DI 1 frequency is also falling over. The problem is that the frequency is getting too high. There are a couple of solutions to this depending on your setup.

1. Use a different speed source

2. Use a frequency divider device

3. Reduce the number of teeth on the wheel of the speed signal generator.

Cheers,

Scott

[Jeremy Towers]

Thanks Scott. But those are time consuming/expensive solutions for me or anyone else who finds this problem in the future.

There is nothing special about the standard Tremec/GM speed sensor in the gearbox. I did do a test on a spare DI and maximum frequency readable by the G4 is around 1600Hz. This corresponds to my 180km/h. I don't see anywhere in the manual that it mentions this frequency as a maximum though.

I can guess the limitation is due to DI sampling speed or digital noise filtering in the G4. Is there any chance of updating the code so it is compatible with these newer transmissions (higher pulse speeds)?? or is there a hardware limitation?

 

Thanks, Jeremy

[Scott]

Hi Jeremy,

It is the current limitation on the system,

I have added your request to the wish list. Unfortunately I can not give you a time frame.

Cheers,

Scott