- Sep 2, 2012
- 468
I don't get around here much, and leave far too many threads unfinished AFAIC, but I thought it would be helpful and interesting to others to summarize my experience & results over the last year with the PCM tune from PCMforless. I had wanted to post my observations earlier, but felt it would be premature to comment on any change in gas mileage until I had adequate data - by now I have probably forgotten or gotten used to some of the differences, but I'll try to note the things that stand out.
I took possession of my 'Voy July 4 2012 with 170739km on the odometer. I had become familiar with the OS and eventually with GMTNation while I was researching the vehicle prior to purchase. I learned of the PCM tunes and how well regarded the people and products at PCMforless were through this forum. I bought the tuned PCM somewhere around Dec 2012, but never got around to installing it until Apr of 2013. I was mostly hoping for a small improvement in gas mileage, and maybe a little more zest on the performance side. The tune was pretty basic as the truck is stock - the only real input choices I made were for Shift Firmness 2 (the recommended choice), 87 Octane, & No towing. I also gave them my usual elevation but everything else was left as stock or to tuner's choice.
By the time of installation, I had put on 27355km with total fuel consumption of 5328.44L (by receipts) for a calculated consumption rate of 19.48L/100km {16998mi / 1407.6gal / 12.075mpg}. The type of driving I do has remained very consistent since I first bought the truck, with pretty consistent monthly mileage and pretty consistent 65/35 city/highway split. At the time of PCM install, my DIC was indicating 5251.7L of fuel consumed and 26828.8km driven for a calcuted consumption rate of 19.57L/100km, but I had reset the entire DIC just a few days after I picked up the truck and started tracking gas mileage on Fuelly.com, so the minor discrepancy isn't a surprise. The DIC indicated fuel consumption rate at this point was 19.5L/100km, VERY accurate in comparison with both the results above.
Installing the PCM was pretty painless and simple except for a little silicon gasket that I discovered hiding on the intake manifold under my PCM...turns out to have been for the temp sensor I had replaced earlier, but its prescence threw me for a loop for a bit while I tried to figure out where it belonged on the PCM! ;-)
I had to do the standard security relearn, but to date I have not yet done the CASE relearn. Part of that choice was based on erroneous feedback from a mechanic that claimed to have work in a GM dealership shop.
May03LT's video on the process has since clarified that for me but I still haven't gotten around to doing it.
The new PCM messed up my OLM indicator. Prior to install it was at something like 30%, after install it was showing 74% - no big deal, I just manually corrected for it until the next oil change.
I did definitely notice an immediate change in the shift behavior of the tranny. The positive changes were snappier shifts under most throttle conditions and though it did feel like it had a little more power, April is also the time where the weather is starting to get cool but not COLD and I would say the performance felt very much like cool weather behavior prior to the tune (IOW, I can't be sure it was really the PCM change). Around my area though there are a couple very common speed limits (50km/hr and 80 km/hr, roughly 30mph & 50 mph respectively), where under very light throttle applications the 2-3 and 3-4 downshifts seem to be a little "reluctant". I often either have to accelerate a bit more aggressively or just give it a little gas and release the throttle slightly to induce the shift. From some other threads I have read, this may be more tranny related than PCM/torque managment related, so take that one with a grain of salt.
For the first month after installation, I may have played around a little and been more aggressive with my driving as I enjoyed the new behavior, but I drive a LOT and settled down into my "normal" habits fairly soon after.
Now for the measured results: After 1 year with the tune, I have put on another 35190.4 km / 21866.3mi, and used 6926.06 L / 1829.67gal of gas for calculated consumption of 19.68L/100km / 11.951mpg. This winter may have been a little tougher, colder more often and definitely had more snow days where I enjoyed the living hell outta 4wd
so I might reasonably expect to have slightly worse gas mileage than the comparable period prior to PCM upgrade. Further, the 1-year data enjoys a bias to better mileage by virtue of having been able to use summer gas blends and less warmups & idling for the roughly 3 months from Apr - July.
Recalculating the data to reflect similar 9 month periods for fairer comparison (July 2012 - Apr 2013 vs July 2013 - Apr 2014) gives this: With the tuned PCM installed I did 25277.7km / 15706.8mi and used 5132.8L / 1355.94gal of gas for calculated consumption of 20.31L/100km / 11.58mpg!!!!!
For those wondering, that gas cost me $8550 in the last 12 months or $6600 in the last 9 months. In 21 months I have driven 62500km / 38800mi on total gas costs of $15100 {$0.24/km or $0.39/mi}, just a little less than 3 times what I paid for the truck
When I think of what I could have done with that......
But with 5 kids I need to transport regularly, as well as a shitload of telescope, camping and camera gear I guess this is the price I gotta pay and I still love the truck.
Anyhow, the bottom line is the tune didn't really help my gas consumption any. Others have had a mild improvement though, and so there may still be factors I'm unaware of at play that are interfering with me getting better results.
That's about all I got...
Cheers folks
I took possession of my 'Voy July 4 2012 with 170739km on the odometer. I had become familiar with the OS and eventually with GMTNation while I was researching the vehicle prior to purchase. I learned of the PCM tunes and how well regarded the people and products at PCMforless were through this forum. I bought the tuned PCM somewhere around Dec 2012, but never got around to installing it until Apr of 2013. I was mostly hoping for a small improvement in gas mileage, and maybe a little more zest on the performance side. The tune was pretty basic as the truck is stock - the only real input choices I made were for Shift Firmness 2 (the recommended choice), 87 Octane, & No towing. I also gave them my usual elevation but everything else was left as stock or to tuner's choice.
By the time of installation, I had put on 27355km with total fuel consumption of 5328.44L (by receipts) for a calculated consumption rate of 19.48L/100km {16998mi / 1407.6gal / 12.075mpg}. The type of driving I do has remained very consistent since I first bought the truck, with pretty consistent monthly mileage and pretty consistent 65/35 city/highway split. At the time of PCM install, my DIC was indicating 5251.7L of fuel consumed and 26828.8km driven for a calcuted consumption rate of 19.57L/100km, but I had reset the entire DIC just a few days after I picked up the truck and started tracking gas mileage on Fuelly.com, so the minor discrepancy isn't a surprise. The DIC indicated fuel consumption rate at this point was 19.5L/100km, VERY accurate in comparison with both the results above.
Installing the PCM was pretty painless and simple except for a little silicon gasket that I discovered hiding on the intake manifold under my PCM...turns out to have been for the temp sensor I had replaced earlier, but its prescence threw me for a loop for a bit while I tried to figure out where it belonged on the PCM! ;-)
I had to do the standard security relearn, but to date I have not yet done the CASE relearn. Part of that choice was based on erroneous feedback from a mechanic that claimed to have work in a GM dealership shop.
May03LT's video on the process has since clarified that for me but I still haven't gotten around to doing it.
The new PCM messed up my OLM indicator. Prior to install it was at something like 30%, after install it was showing 74% - no big deal, I just manually corrected for it until the next oil change.
I did definitely notice an immediate change in the shift behavior of the tranny. The positive changes were snappier shifts under most throttle conditions and though it did feel like it had a little more power, April is also the time where the weather is starting to get cool but not COLD and I would say the performance felt very much like cool weather behavior prior to the tune (IOW, I can't be sure it was really the PCM change). Around my area though there are a couple very common speed limits (50km/hr and 80 km/hr, roughly 30mph & 50 mph respectively), where under very light throttle applications the 2-3 and 3-4 downshifts seem to be a little "reluctant". I often either have to accelerate a bit more aggressively or just give it a little gas and release the throttle slightly to induce the shift. From some other threads I have read, this may be more tranny related than PCM/torque managment related, so take that one with a grain of salt.
For the first month after installation, I may have played around a little and been more aggressive with my driving as I enjoyed the new behavior, but I drive a LOT and settled down into my "normal" habits fairly soon after.
Now for the measured results: After 1 year with the tune, I have put on another 35190.4 km / 21866.3mi, and used 6926.06 L / 1829.67gal of gas for calculated consumption of 19.68L/100km / 11.951mpg. This winter may have been a little tougher, colder more often and definitely had more snow days where I enjoyed the living hell outta 4wd
so I might reasonably expect to have slightly worse gas mileage than the comparable period prior to PCM upgrade. Further, the 1-year data enjoys a bias to better mileage by virtue of having been able to use summer gas blends and less warmups & idling for the roughly 3 months from Apr - July. Recalculating the data to reflect similar 9 month periods for fairer comparison (July 2012 - Apr 2013 vs July 2013 - Apr 2014) gives this: With the tuned PCM installed I did 25277.7km / 15706.8mi and used 5132.8L / 1355.94gal of gas for calculated consumption of 20.31L/100km / 11.58mpg!!!!!
For those wondering, that gas cost me $8550 in the last 12 months or $6600 in the last 9 months. In 21 months I have driven 62500km / 38800mi on total gas costs of $15100 {$0.24/km or $0.39/mi}, just a little less than 3 times what I paid for the truck
When I think of what I could have done with that...... But with 5 kids I need to transport regularly, as well as a shitload of telescope, camping and camera gear I guess this is the price I gotta pay and I still love the truck. Anyhow, the bottom line is the tune didn't really help my gas consumption any. Others have had a mild improvement though, and so there may still be factors I'm unaware of at play that are interfering with me getting better results.
That's about all I got...
Cheers folks
