I heard from a transmission specialist that in some newer gm vehicles you can send in your stock pcm and they can reprogram or reburn your computer to read a different gear ratio. Is this true? Does anyone know who would do this? The man he was talking about lives somewhere in NY state. Does anyone know about this?
1. I don't even think the PCM contains any information about gear ratios for autos or manuals (at least not for J's)
and
2. What good does telling the car the ratio is different without actually changing to larger or smaller gears?
Are you talking about extending your rev limiter? If so then yes, you can do it yourself with HPTuners.
Otherwise, I think you are going to have to explain this a little more because cars don't run purely on the magic of programming.
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"Youth in Asia"...I don't see anything wrong with that.
I was going to switch the gears to a lower gear ratio, in the end result of 3.91 gear ratio. what is the hptuner you are talking about? are there any companies that make other tuners like superchips or other companies like that or is the hptuner what you are talking about?
Most modern pcm's contain transmission calibration info which has a final drive ratio and speed sensor pulses per mile for speedo calibration. Generally these can be altered by tuning software. Someone more familiar with HPT could answer whether or not these values are available to adjust in that package.
-->Slow
who would know more about hptuners.
thank you very much thats what I needed to know unless if you hear of the person modifying the computer
Quote:
unless if you hear of the person modifying the computer
Tony, maybe you misunderstand something. Most of the people on this forum are modifying the computer themselves using HPTuners. HPT does not modify anything for you, it sells you the software to do it yourself. There are many big tuning shops across the country who have purchased HPT and will offer to do it for you. The difference is you pay the pro shops big money to make the changes, and if you want more or don't like the results, you pay them again to make new changes. If you buy HPT and learn to use it yourself you can save large amounts of $$ making as many changes as you little heart desires. At the very least, look for a member of this forum willing to make changes for you. For what you're asking, you should be able to get it done fairly reasonably.
-->Slow
NOTE*
If you're thinking that you can take your stock computer to the dealership and have stuff changed, you can't. They can only reprogram to a factory program. And you can't send your PCM in somewhere. Besides, while you're waiting on it to ship and all your car will have to sit in the driveway.
A lot of guys with trucks that put big tires on there order an electronic part which corrects the speedometer for them. Would have the same effect if they changed gear ratio's too I believe. Though, on the j-body even if you changed your FDR, your speedometer output would stay the same, since it measures the speed of the car after the final drive gear. So the speedometer itself would still be correct, though different subroutines in the computer would probably be off.
What kinda car did the guy drive that was telling you about this?
