7AT tranny <40mph
09-04-2009, 01:03 AM
#1
7AT tranny <40mph
anyone else noticing how in D, @ 40mph city driving the tranny is in 6th and 1300rpm? is this normal? I've never driven a car that cruises @ 12-1500rpm...
it's like killing my mpg... 16.7 mpg... not to mention I can't accelerate cause it takes a few seconds for the car to shift out of 6th...
it's like killing my mpg... 16.7 mpg... not to mention I can't accelerate cause it takes a few seconds for the car to shift out of 6th...
09-04-2009, 03:07 AM
#2
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Normal for this car. I have the exact same issues. If you go through the threads under "G37 Transmission Issues with 4th -> 3rd Downshift", you'll have a better idea about G37's transmission issues.
09-04-2009, 05:25 AM
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Mine was made in Nov 2008. When I took it to the dealer 3 weeks ago for the TSB update, they told me I already had the latest one.
My car has always been like that when driving under 40MPH. The worst bogging and lowest RPM (around 950) occurs at about 37MPH, especially when the A/C is off.
Definitely, the tranny smoothed out quite a bit after I passed 7,500 miles. But the 37MPH bogging is still there. One thing I learned to get over this point is to use the paddle shifter to lower the gear. But that only helps momentarily.
On the other hand, my mileage is quite good for mixed city-hwy driving. I average about 24MPG.
My car has always been like that when driving under 40MPH. The worst bogging and lowest RPM (around 950) occurs at about 37MPH, especially when the A/C is off.
Definitely, the tranny smoothed out quite a bit after I passed 7,500 miles. But the 37MPH bogging is still there. One thing I learned to get over this point is to use the paddle shifter to lower the gear. But that only helps momentarily.
On the other hand, my mileage is quite good for mixed city-hwy driving. I average about 24MPG.
09-04-2009, 08:55 PM
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09-04-2009, 10:13 PM
#8
I don't think it's the same as the TSB. the TSB addressed the 4th to 3rd down shift, which I actually don't experience... just weird, cause I know there's this "power swell" but it's almost like it doesn't let you accelerate as fast as it should
low rpm doesn't always equal good mpg.
when you're in a high gear, at a low rpm, you're pushing more fuel to do less work. where as normally the fuel consumption is efficient.
low rpm doesn't always equal good mpg.
when you're in a high gear, at a low rpm, you're pushing more fuel to do less work. where as normally the fuel consumption is efficient.
09-05-2009, 10:33 AM
#9
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This is normal. The car is programmed to shift into the highest gear at all times and as quickly as possible to conserve fuel. The AT 335i I test drove did the same thing. I was in second gear within 5 ft. of taking off and unless I came to a complete stop, the car would stay in 2nd gear.
09-05-2009, 10:33 AM
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As has been discussed many many times, the G has very little torque at low RPMs. The car will probably have to drop a couple of gears before it can really get going if the RPMs are that low.
How will lower RPMs not equal better gas mileage?
40 MPH at 3000RPMs is going to be worse than 40MPH at 1300RPM.
The car is only rated around 18MPG city. So 16.5 city is not THAT bad.
How will lower RPMs not equal better gas mileage?
40 MPH at 3000RPMs is going to be worse than 40MPH at 1300RPM.
The car is only rated around 18MPG city. So 16.5 city is not THAT bad.
09-05-2009, 11:52 AM
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I am not sure about that. I have almost 16,000 miles and drive roughly 7 city miles to work. Currently I am getting about 18 MPG in the Sedan. I am a little agressive but although mine is in that low RPM range, there is some take off lag but I do not find it that bad. My wife drives the Coupe to work and has about 15 miles which are more highway (but still rush hour) and she gets over 20 MPG. I am having the TSB loaded on the Coupe and will know more about that next week. I had the TSB loaded on the Sedan about a month ago.
09-05-2009, 06:27 PM
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I just took mine in today and they said my TCM was up to date. They went ahead and updated my ECU and it made a huge difference. I noticed the downshifting problem and read about the fix on this forum.