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confused on my gears

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Old 05-17-2005, 05:24 PM
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Default confused on my gears

posted this at truck too so if youve already read and responded over there, thanks...

to make a long story shorter, allen was in houston a few months ago to do programs. when he plugged into mine he said that the computer was locked up so he couldnt touch it. the truck already had a program on it. i found the guy who programmed the computer and he is a mechanic for a dealorship around here.

i already knew the guy who programmed it so reflashing the pcm was suposed to be an easy and cheap job. when he went to reflash my current pcm it wouldnt let him touch it which would explain allen not being able to touch it. so he warrantied it out and put in a new one and updated it. after i got on the road it was pingin like a **** at WOT and about 3 miles down the road the truck died on me. started it back up and it sputtered all the way to the shop needing a restart every once in a while. he poked around for a while then replaced that new pcm. now its runnin but still pings in the upper rpm's. now allen can finally program my pcm!

anyways when i asked if he needed the gear ratio for the pcm he said it was already set to whatever the vin said was in it. it wasnt a big deal to me since allen is suposed to crack into my pcm here soon but once i got on the road i noticed that @ 70mph i was still running the same exact rpm's ?? i was under the impression that it has 373 gears in it when i bought the truck,and that it was programmed for them. was it never programmed for 373's? and if it wasnt would that be why my truck would hit the rev limiter before shifting to 2nd?


anyways, now for trying to figure out what size gears i have out back. if i have 373 gears, 4l60e, and 245/70-17(30.5") tire running at 2000 rpm, how fast should i be going(im showing 70 with stock pcm). what about if i had a 342 rear end? my glove box says gu6 and thats a single track0 342 if im not mistaken. im positive its posi so i know the rear ends been broken open. does it sound like it was just never programmed for the 373's or do i still have 342's?

am i even going in the right direction to figuring out my gears??? thanks for any help you guys have for me
Old 05-17-2005, 06:43 PM
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Do you have the G80 code in your glove box?
Old 05-17-2005, 07:19 PM
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no but there is a g80 in there. theres suposed to be a 373 too but im not so sure anymore.
Old 05-17-2005, 07:33 PM
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well have you checked the speed next to a friend and seen how fast you really are going. even though the speedo says 70 you might be going 60 and thats why the rpms are low.
Old 05-17-2005, 09:27 PM
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At about 75, I am very close to 2000 rpms. (3.42)
Old 05-18-2005, 12:08 AM
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well have you checked the speed next to a friend and seen how fast you really are going. even though the speedo says 70 you might be going 60 and thats why the rpms are low.
did it earlier. when my speedo is at 100, im actually doing about 80 mph. thats where my gov kicks in now i got ownt by my friends v6 because i couldnt get past 80
Old 05-18-2005, 11:53 AM
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Originally Posted by TXsilverado
did it earlier. when my speedo is at 100, im actually doing about 80 mph. thats where my gov kicks in now i got ownt by my friends v6 because i couldnt get past 80

lift the rearend up and count how many revs of the drive shaft to one rev of the wheel. This will tell you the ratio. That or you can open it and count the teeth.
Old 05-18-2005, 12:59 PM
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i lifted the rear end and it spun the wheel one full revolution but the drive shaft didnt even make it to two revolutions...dont plan on opening it any other tricks?
Old 05-18-2005, 02:24 PM
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instead of turning the wheel turn the driveshaft
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