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SPEED ECU sensor issue
Posted:
Sun Jun 07, 2015 4:26 pmby umbertom
Recently installed the transmission/ECU speed sensor, reading the data into an AIM PISTA system. Speed values are ~8% higher than GPS speed data (which i believe to be accurate).
Sounds like an incorrect wheel diameter assumption.
Anyone else experience this? If so is it an AIM software fix or a parameter I can set somewhere?
for now I am using a math channel of SPEED/1.08
Re: SPEED ECU sensor issue
Posted:
Mon Jun 08, 2015 7:52 amby srf99
I've seen a similar effect, so I've been going with the GPS speed (which I also assume to be more accurate).
Re: SPEED ECU sensor issue
Posted:
Mon Jun 08, 2015 11:19 amby bob gardner
It is not uncommon for car makers to have their speedometer sensors read ~10% faster than actual mph.
Re: SPEED ECU sensor issue
Posted:
Mon Jun 08, 2015 11:20 amby davep
Same issue with the EVO4 system. I am also using the GPS speed.
DaveP
Re: SPEED ECU sensor issue
Posted:
Mon Jun 08, 2015 11:28 amby cnewman92
Is it maybe due to the ring and pinion change?
CN
Re: SPEED ECU sensor issue
Posted:
Mon Jun 08, 2015 12:28 pmby Bill Parenteau
I would think Mike D could (maybe) reprogram the ECU with a multiplier to correct the issue. I don't have the gear in the transmission, so it's not an issue for me until the next rebuild, if I chose to use it.
Re: SPEED ECU sensor issue
Posted:
Mon Jun 08, 2015 1:05 pmby Rod
Umberto, assuming from the fact that you are competitive, I am assuming that you have the 3:85 ring & pinion. That would give you about a 6% delta from the 3:62. That would be awfully close.
Then, don't forget that the AIM system still needs some data on your tire circumference. I think many utilized a 72" tire circumference, but I have found its been closer to 70.5" (with the older tires, don't know about the newer ones).
By tweeking that tire circumference number in the AIM setup, you can probably fudge it.
Rod S