speedo tuning

im looking for someone who has a GM 3400 V6 in a grand am GT. the story is im trying to do a gauge pod swap on mine. the SEs came with a speedo that pegged at 120mph and the GTs have a pod that goes to 150mph. i was wondering if i could change the VSS pulses per mile and tranny pulses per mile ect and get the car to accurately read the speed on the gauges. ive had them in the car before and the speed was off. the needle would always be where it shud be to read the correct speed on the 120 gauge. so 60 was showing as 75ish. any ideas? there arent any tunes in the repository for this car.

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Originally Posted by lowrider2962

i was wondering if i could change the VSS pulses per mile and tranny pulses per mile ect and get the car to accurately read the speed on the gauges

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Not sure if it would work but if it did, the gauge would be right but the VCM would be wrong.

thats true but the only things i can think of that the VCM uses the speed of the vehicle for is shift points. considering its a 5 speed it shudnt be a problem, right?... i realize its also used in DFCO but that can easily be retuned to the same characteristics by using different numbers... wat do ya think?...

I was going to say it would mess up your shifts, but like you said, having a stick it shouldn't be an issue. Try it, do some quick division to figure out the percentage you are off and adjust by that amount.

VCM uses vehicle speed for more than just shifting the transmission.

In the late model cars it is very involved, cluster, radio etc., in his car there isn't much aside from the transmission that involves speed reference. It's as simple as trying it, if it doesn't work just go back to the previous bin.