GDE TCM Tune, a review.

flman · **Posted:** Fri Jun 18, 2010 3:32 pm

DOC4444 wrote:

You are correct. The OEM TCM has the engine returning to idle whenever you let off. However, there is a proven fuel economy benefit to keeping the TC locked when you let off the throttle. Think about it. When you drive a manual trans vehicle, you don't step on the clutch everytime you let off the throttle. This is one (not the only, though) reason why stick versions of vehicles usually return significantly higher real world MPG than the same vehicle with an auto trans.

GDE made this change by design and it is benefitial in all situations including towing and not.

BTW, most of the fuel economy benefit from the tune comes BELOW 50 MPH. I am sure GDE will make you a "custom" tune that does not lock until your desired speed (i.e. 50 instead of the "standard" 35 MPH).

DOC

I find my self stepping on the accelerator in situations where I am normally coasting. With a standard I could coast in a higher gear without stepping on the accelerator. So I am not totally sure that accelerating when I could be coasting at idle is beneficial. How much fuel can this little engine burn idling any ways? I am not trying to pinch pennies here.

DOC4444 · **Posted:** Fri Jun 18, 2010 6:24 pm

Flman,

I understand you think you would be using less fuel "coasting", but GDE's testing clearly showed better mileage keeping the TC locked. They can change it back for you, but you will spend more for fuel, everything else being equal.

DOC

flman · **Posted:** Fri Jun 18, 2010 7:21 pm

DOC4444 wrote:

Flman,

I understand you think you would be using less fuel "coasting", but GDE's testing clearly showed better mileage keeping the TC locked. They can change it back for you, but you will spend more for fuel, everything else being equal.

DOC

Where is this test? Is it various driving or is it multiple tests based on multiple conditions?

DOC4444 · **Posted:** Fri Jun 18, 2010 9:43 pm

GDE have not published their TCM development data.

DOC

flman · **Posted:** Sat Jun 19, 2010 8:51 pm

I found a way to get around objectionable down shifts or unlocks when on a windy county road, is to put OD off. It also puts the RPMs at a higher speed.

mdalien · **Joined:** Tue Jun 22, 2010 10:22 pm **Posts:** 41

After reviewing numerous posts I did the Eco Tune and the TCM tune.\
I have put ~200 miles on it and am quite happy with it.

The only thing I have found is that I drive hilly country and the lockups can occur too early.
It is a learning curve to either keep the speed down or manually drop gears.

geordi · **Posted:** Thu Jun 24, 2010 2:56 am

Idle fuel consumption with accessories running is 1 quart per hour.

flman · **Posted:** Thu Jun 24, 2010 5:54 am

geordi wrote:

Idle fuel consumption with accessories running is 1 quart per hour.

Not much, that would add up to alot of coasting. And if I have to step on the accelerator where I used to be able to coast at idle, I would say I am burning more fuel.

GDE TCM Tune, a review.

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