Automatics changing my view.

[theholycow]

Originally Posted by dkjones96

That just HAS to be an exaggeration. I can't (and won't) believe for a second that the engine has to create anywhere near 15-20 more hp if the car is in gear vs neutral.

In fact, if I remember correctly from my data logging on Tracker, calculated load was mostly unaffected(+-1%) by neutral vs drive. However, turning on the a/c yielded a 15% increase in calculated load.

Fuel rate is barely affected by D vs. N at a stop, but it is affected. Injector duty cycle might be ~1.3% in N and ~1.5% in D. That's a pretty significant difference comparing the two, but the amount we're talking about isn't much. It is enough to be worthwhile, IMO...you don't have anything to lose by doing it.

Originally Posted by VetteOwner

maybe theyve changed alot since 97

I believe that they have. I think in addition to adding gears (Many 2008 GM autos are 6 speed, vs. all being 4 speed in 1997), the computer control has been worked on and the programming improved. Most come with some kind of manual control, and I suspect that they have been made more robust to tolerate that combined with 100,000 mile warranties.

I don't know if this is attributable to 5 (or 15) years difference or just the difference in vehicles, but my 2002 GMC's transmission behaves way better than my 1997 Pontiac or 1987 Cadillac did. The Pontiac and Cadillac revved too high (and the Cadillac had a power curve like a diesel, really needing low-RPM high-torque driving), while the GMC shifts low and lets me put some gas pedal into it without jumping to redline at the drop of a hat...but if I drop the hammer, it downshifts right away and takes off.

doesnt engine brake at all (well does but takes a friggin mile to do so)

Most automatics should not engine brake automatically under most conditions. It is more efficient to go to the highest gear and unlock the torque converter when the driver lets off the gas pedal.

An automatic driver who wants engine braking is advised to make use of the different positions for the gear selector, or on late model vehicles, to use the tiptronic/paddle shifters/etc. That's one of the main reasons those things are included in the user interface.

since we like to do our own service work that when a computer buggers up or something fails and throws the SES light were SOL since we dont own a obdII scanner or anything...

You don't have to spend $200 on a ScanGauge to get an OBDII scanner. Harbor Freight sells a basic unit that will pull codes from any car for $40, or you can go to the nearest chain auto parts store like Auto Zone and get your codes pulled for free (make sure you insist on getting the code numbers instead of just the vague description) (illegal in California).

[VetteOwner]

yea weve thought about getting that cheapo scanner(not like we use it everyday) but then ya gotta consider ok it says X code, look it up find out its a camshaft position sensor. then theres 3 problems: 1: where the hell is that located 2: do i need arms like gumby and a lift to see it let alone get to it 3: is that really the cause? as we all know (yes this is true of old cars too) that one part can seem to fail when another one that is actually failing causing it to do so.

yea forgot about that whole downshifting to redline thing the tarus does, seems you press the pedal, seems to jump down 2 gears redline then go back up one.

6 speed wouldnt be too bad hell of alot better than the 80's 3 speeds lol

[theholycow]

Yeah, the scanner doesn't troubleshoot, identify, and fix the problem for you...it just alleviates the problem of being SOL without it. You get the code, and it gives you some direction. You check the sensor or try to figure out what might provide incorrect readings at that sensor.

[GasSavers_RoadWarrior]

Originally Posted by VetteOwner

6 speed wouldnt be too bad hell of alot better than the 80's 3 speeds lol

Going by what people report as highway RPM on some vehicles, yep, my 80's 3 speed is not bad. ~2500-2600RPM @ 60 with the TC locked up.

[VetteOwner]

i do wish my chevette had the 5 speed... its at 3K at 60mph...

[101mpg]

I can attest that some vehicles actually use a LOT of engine in neutral - because the torque converter converts SOME - all of the time.

You may try the Malibu Maxx - it is roomier than the Malibu, 6" longer wheelbase but 1/2" SHORTER than the Malibu! - and it gets better mileage.

Can get it over 40 in the right conditions. The Maxx just Roxx!

[theholycow]

How would the torque converter do any work if its output side is unloaded?

[101mpg]

That's the thing - it's not actually unloaded entirely! The Malibu Maxx & the Grand Caravan actually stay "in gear" when in neutral - keeps the fluid spinning to cool it I guess. And there is an audible as well as you can feel the vehicle slip out of gear once you get below 5 MPH if you coast to a stop!

Plus you can view it on the MPG readout as well - but it does not entirely go into neutral.

[GasSavers_RoadWarrior]

Park actually lowers the lube pressure or stops running the pump on some vehicles (Chrysler transmissions do it) so idling in Park should take less gas than idling in neutral. Might only notice this with a small motor though, hemi truck it might not make a difference.

[asjdkasj]

hemi truck it might not make a difference.yes