TCM mod impressions
#1
02-23-2004, 01:41 PM
Join Date: Jan 2004
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TCM mod impressions
So I finally decided to try the TCM mod and have a few observations.
First, the tranny does shift more firmly and launchs are slightly harder. Since it is difficult to feel .5 seconds 0-80 I am not sure this mod is something everyone should do for normal driving. For the kids and parking lot racers I think it is fine. I was hoping to see differences in the way the tranny responded to a load not how it would shift during a WOT drag.
That leads me to the towing impression and torque useage issue. As an example the tranny will now stay in 3rd gear longer under load ACTUALLY using the available torque the motor is producing. I have noticed as throttle input increases the speed of the vehicle increases at a much higher rate than the rpm. Before the truck would start to accelerate but as the torque demand increased the tranny would sort of sit there until more fuel was added and finally it would shift down. So bottom line is that the tranny does not shift as much. Another example is the way the truck reacted in OD. Yesterday I drove a 100 mile round trip test and noticed the tranny would stay in 5th on fairly steep pulls and would select 4th as well if needed. Before the mod the dang thing would jump right to 4th and most of the time drop to third.
Fuel mileage also appears to be much better. On this same route before the mod I was getting 12.5, this trip netted 15. That is the best mileage this truck has ever gotten! This is still up in the air so time will tell. The next step is to determine if it makes any difference in town driving. Before the mod with OD on I get 9, with OD off I get 10.2, this morning I got 13 but that is not a good test and probably only giving me false hope. It will take several days to get a decent average going.
THE PROBLEM: I have noticed the rpm bouncing around about 100 rpm on down hill sections and again this morning in town when NOT under a load. THIS MAKES ME VERY NERVOUS. I wish we could get a tranny specialist or master mechanic on this forum to let us know if we are a bunch of dumbarses or not for messing around with this mod.
First, the tranny does shift more firmly and launchs are slightly harder. Since it is difficult to feel .5 seconds 0-80 I am not sure this mod is something everyone should do for normal driving. For the kids and parking lot racers I think it is fine. I was hoping to see differences in the way the tranny responded to a load not how it would shift during a WOT drag.
That leads me to the towing impression and torque useage issue. As an example the tranny will now stay in 3rd gear longer under load ACTUALLY using the available torque the motor is producing. I have noticed as throttle input increases the speed of the vehicle increases at a much higher rate than the rpm. Before the truck would start to accelerate but as the torque demand increased the tranny would sort of sit there until more fuel was added and finally it would shift down. So bottom line is that the tranny does not shift as much. Another example is the way the truck reacted in OD. Yesterday I drove a 100 mile round trip test and noticed the tranny would stay in 5th on fairly steep pulls and would select 4th as well if needed. Before the mod the dang thing would jump right to 4th and most of the time drop to third.
Fuel mileage also appears to be much better. On this same route before the mod I was getting 12.5, this trip netted 15. That is the best mileage this truck has ever gotten! This is still up in the air so time will tell. The next step is to determine if it makes any difference in town driving. Before the mod with OD on I get 9, with OD off I get 10.2, this morning I got 13 but that is not a good test and probably only giving me false hope. It will take several days to get a decent average going.
THE PROBLEM: I have noticed the rpm bouncing around about 100 rpm on down hill sections and again this morning in town when NOT under a load. THIS MAKES ME VERY NERVOUS. I wish we could get a tranny specialist or master mechanic on this forum to let us know if we are a bunch of dumbarses or not for messing around with this mod.
#2
02-25-2004, 01:37 PM
Join Date: Jan 2004
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RE: TCM mod impressions
So far the fuel mileage in town and town like conditions has been in the 12-12.5 range. As of this morning it was 12.7 but I am not sure if that is going to hold or not. I pulled a heavy steel 3 place sled trailer with two sleds on it across town and the mileage did not change, surprised.
So it appears that I am now getting 3-3.5 mpg better in town than a week and half ago with the OD off and the TCM mod. The 15 mpg average to the race site and back was a surprise as well since the last time I did the same trip I got 12.5.
I sure hope this mod has no negative effects. We are putting it on the computer Friday to see if the PCM has thrown any codes.
The next step will be to add K&N and perhaps an exhaust to free up some more power, get better mileage, and reduce the heat in the exhaust system etc.
So it appears that I am now getting 3-3.5 mpg better in town than a week and half ago with the OD off and the TCM mod. The 15 mpg average to the race site and back was a surprise as well since the last time I did the same trip I got 12.5.
I sure hope this mod has no negative effects. We are putting it on the computer Friday to see if the PCM has thrown any codes.
The next step will be to add K&N and perhaps an exhaust to free up some more power, get better mileage, and reduce the heat in the exhaust system etc.