Mileage reports: Automatic transmission (5AT)
#1041
Can you explain what makes the transmission lock/unlock and why that would be good or bad?
Also, if you left it in D, the fuel should have cut off, giving you (effectively) infinite mpg.... Or so I've heard; I won't know for sure until I get a scangauge, which I keep putting off on account of the wife.
Also, if you left it in D, the fuel should have cut off, giving you (effectively) infinite mpg.... Or so I've heard; I won't know for sure until I get a scangauge, which I keep putting off on account of the wife.
Total lock-up means the transmission is in a more efficient mode -- slippage is eliminated. I assume the car tries to lock-up the a/t whenever it can for better mpg, but I'm not sure of all the parameters that control the mechanism.
Putter down the freeway in 5th (paddle mode) at 60 mph. Now floor it, and the rpms will jump as it leaves total lock-up mode. Cruise again, and it will lock back up.
#1042
How can you tell when it is locked? Actually, if I'm in 5th going 60 mph and floor it, my RPMs remain relatively unchanged; I have very little acceleration in 5th above 3k RPM. Maybe my lockup thingy is broken?
Does DFCO occur in gears other than 5? If you're going to hit the RPM range where DFCO stops so you downshift to 4 to keep your RPMs up, does DFCO still occur even though your only in 4th? Thanks for the help!
Does DFCO occur in gears other than 5? If you're going to hit the RPM range where DFCO stops so you downshift to 4 to keep your RPMs up, does DFCO still occur even though your only in 4th? Thanks for the help!
#1043
mpg
With gas prices rising, I've tried to be more conscious of my driving habits this past tank of gas. No jackrabbit starts, kept the rpm's under 3000 the whole time, ran with the windows up and vents on (no AC) when practical. I let my foot off the gas when I see a stop ahead.
Did not use cruise control, and did not put the car into neutral at any time. I had to use the AC a few days as it's starting to get really hot out.
Got a solid 34 mpg city. Very pleased.
Did not use cruise control, and did not put the car into neutral at any time. I had to use the AC a few days as it's starting to get really hot out.
Got a solid 34 mpg city. Very pleased.
#1044
How can you tell when it is locked? Actually, if I'm in 5th going 60 mph and floor it, my RPMs remain relatively unchanged; I have very little acceleration in 5th above 3k RPM. Maybe my lockup thingy is broken?
Does DFCO occur in gears other than 5? If you're going to hit the RPM range where DFCO stops so you downshift to 4 to keep your RPMs up, does DFCO still occur even though your only in 4th? Thanks for the help!
Does DFCO occur in gears other than 5? If you're going to hit the RPM range where DFCO stops so you downshift to 4 to keep your RPMs up, does DFCO still occur even though your only in 4th? Thanks for the help!
Its only present in Automatic Transmissions.
#1045
Using the scangauge last night, it's better I think to keep the transmission in total lock-up. Better to (sport a/t) put into 4th locked, than to let the motor strain in 5th in slushbox mode (no lock up).
Same principle for small hills, the a/t will leave lock-up mode, so pop it out of cruise control and bleed the speed until the crest.
Coasting down the Altimont in N for 3 minutes at 70 mph @ 270 mpg was fun...
Same principle for small hills, the a/t will leave lock-up mode, so pop it out of cruise control and bleed the speed until the crest.
Coasting down the Altimont in N for 3 minutes at 70 mph @ 270 mpg was fun...
#1047
Ghostagent, keep a record of the mileage and take the car into the dealer. First though, remember to drive smoothly, no rapid starts or stops and try to drive as efficiently as possible (hard to do in city driving, I know). Driving style helps a lot. 24 mpg in the city seems low though. I've never seen anything below 29 in the city, even with the air on.
Good luck.
Good luck.
#1049
Man, stoplights are brutal according to the scangauge. I mean, it's obvious of couse, but it hurts to watch it in real time! Cue the Chevy ad tune... "Like a rock!" Also, the first few minutes are low mpg for whatever reason, cold engine.
Last edited by xorbe; 06-04-2008 at 01:59 PM.
#1052
My last tank - 33 mpg (283/8.53) with mixed driving and little AC. I've got 3K miles on the car. I've increased tire inflation to 42 psi, use DFCO as much as possible, and accelerate slowly from a stop. DFCO FTW!!
This mpg figure is based on my actual odo reading may be low as my odo is now off by 6-8% due to a change from steelies to alloys based on GPS calibration. I need to do a more thorough calibration to really see how much my readings have changed. If I'm right, this may be 36 mpg or more!!
This mpg figure is based on my actual odo reading may be low as my odo is now off by 6-8% due to a change from steelies to alloys based on GPS calibration. I need to do a more thorough calibration to really see how much my readings have changed. If I'm right, this may be 36 mpg or more!!
#1053
My last tank - 33 mpg (283/8.53) with mixed driving and little AC. I've got 3K miles on the car. I've increased tire inflation to 42 psi, use DFCO as much as possible, and accelerate slowly from a stop. DFCO FTW!!
This mpg figure is based on my actual odo reading may be low as my odo is now off by 6-8% due to a change from steelies to alloys based on GPS calibration. I need to do a more thorough calibration to really see how much my readings have changed. If I'm right, this may be 36 mpg or more!!
This mpg figure is based on my actual odo reading may be low as my odo is now off by 6-8% due to a change from steelies to alloys based on GPS calibration. I need to do a more thorough calibration to really see how much my readings have changed. If I'm right, this may be 36 mpg or more!!
#1054
I replaced my steelies with OEM sport alloys so I'm running the same wheels/tires as many Sport owners. My base doesn't have the skirts and spoiler though.
#1056
Per the math, the difference between the steelies and the alloys is about 2%. The steelies are 14", the alloys are 15" rims. I measured the difference at around 6-8% with my GPS. The odo may have been off to begin with or tire circumference may not be an exact science. I can't say which but I can say I was surprised the difference was much larger than the math said it should.
Either way, 33 with the AT is still pretty darn good.
Either way, 33 with the AT is still pretty darn good.
#1059
Traffic was thick tonight so I drafted a semi truck at 55 mph and averaged 47.2 mpg over 88 miles according to the scangauge... it's nuts, like 50-60 mpg when drafting at that speed!! But no fun at all, and not safe, but still impressive.