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Discussion Starter · #1 ·
Ok so I recently went from 2.73 gears to 3.73 gears and I noticed when WOT I would hit the rev limiter 2-3 shift and not shift into 3rd. I know you need to get the pcm tuned and shift points adjusted, so I sent my pcm out to get it tuned after receiving my pcm back I’ve noticed it’s still 5MPH off and I’m still having the same problem. Any suggestions?
 

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I'd send the computer back for a retune. While 4l60e has problems with wot shifting that are hard to tune for, the speedometer should not be 5 mph off.
 

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You 100% need to have to get a retune to compensate for the gear change. Found this out the hard way myself. Solomon can do it through he mail.

EDIT
I'm not sure what year your ride is. My old Formy was a '94, OBD1, so I bought the cable and software to data log. I found that the PCM thought the car was going 1 speed, the dash was telling me another speed and the GPS on my phone was giving a third number, all different. If memory serves me, if the PCM said I was going 64 mph, the dash said 68 and the GPS was at something like 60. (or some weird combination like that, I cant remember the specifics, he was able to take that info and calibrate the speed in the PCM and the issue went away. The whole thing was pretty fascinating and something I struggled with from the day I bought the car.
 
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