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| Author: | txbiker [ Sat Mar 07, 2015 12:51 pm ] |
| Post subject: | shift points |
I need some info from more experienced CRD owners What are the shift points (indicated speed) for high gear? Sometimes at 55-60 mph I am indicating less than 1800 rpm and at other times I am indicating >2k. I am preparing for a long highway trip and would like to know the most economical speed to travel. Thanks |
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| Author: | papaindigo [ Sat Mar 07, 2015 1:14 pm ] |
| Post subject: | Re: shift points |
Depends but I'll try to keep it relatively simple. 1. original shift point into top gear/OD from the factory was about 57/58mph or around 1700rpm 2. that combined with engine power (HP and torque) and either the original torque convertor with the plastic part (only very very early 05s) or the later 05/06 torque convertor (not the 07 "Euro" TC) caused TC problems that DCJ decides to "solve" by the F-37 recall (detune engine power via the ECU; raise the final shift point via the TCM; and check the TC with a replacement as needed but not with the Euro). This produced a final shift point more like 63-64 mph or slightly above 2000rmp 3. #2 notwithstanding some got "lucky" and the dealer "forgot" to reprogram the TCM so such a vehicle retained the #1 final shift point. My 05 was one of those vehicles. 4. regardless of the above once your vehicle has in fact reached the appropriate speed AND accomplished that final shift it will hold that shift point down to a lower speed. Hence if you meet the factors in #2; reach 63-64 and make the final shift; then you can drop back to ca. 62mph and hold 1800 rpm. However, if you do not make that final shift (e.g. just run up to 60-62) you will actually be in a lower gear hence your rpm will be at or over 2000. GDE sells several TCM tunes one of which approximates the original (#1) final shift point. PS you are driving an aerodynamic brick but optimum mpg seems to be around 1800 rpm at about 61-62 mph all things being equal. |
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| Author: | txbiker [ Sat Mar 07, 2015 4:29 pm ] |
| Post subject: | Re: shift points |
Thanks to papaindigo I feel a bit better about the shift points. Checking my carfax shows the the Engine/powertrain computer/module reprogrammed on 3/20/06. I am hoping an ecu flash will restore it. I am looking at an ecu reflash after I get over the finance of timing chain replace when the snow melts so I can get to the barn. LOL Thanks for all the info that is available fromthe members of this forum. |
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| Author: | papaindigo [ Sat Mar 07, 2015 5:11 pm ] |
| Post subject: | Re: shift points |
GDE sells 2 classes of flashes: 1. ECU - there are several variations but unless you want lots of extra power (most power requires a torque converter upgrade) your best bet is the EcoTune which noticeable boosts power (without overstressing the stock TC), improves mpg, substantially reduces soot going into the intake from the EGG and other good stuff. This does not do anything about the shift points. I view this as a very desirable investment; in my case and stoutdog's it jumped mpg from 18/24 or so to 24/32 or so. 2. TCM - again there are several including special ones for those that tow a lot of relatively heavy stuff. The minimal TCM tune has several improvements over the F-37 detune including restoring the original final shift mph/rpm point and allowing holding that gear to a lower speed than the pre-F-37 did. In hindsight since my 05 had "escaped" the TCM F-37 detune so it had the original shift point I probably would not have purchased this tune. That said if you do a fair amount of driving at less than interstate speeds you will see some benefit. If not just get used to running up to the mph/rpm you need to get into that final shift and then drop back to ca. 62mph/1800rpm for good mpg. |
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| Author: | DOC4444 [ Mon Mar 09, 2015 9:02 am ] |
| Post subject: | Re: shift points |
What Pap did not mention about the TCM tune is that it locks the torque convertor at 35 MPH and keeps it locked until you get to about 3/4 throttle. This improves MPG about 3-4. Also, the tow tune allows you to actually use 4rth gear. It holds the shift to 5th until 70, but stays in 5th until you drop below 55. It is a must if you tow a heavy trailer. Keith can custom tune shift points to your preference, as well. DOC |
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