Few questions for easy, $0.00 modifications

[theholycow]

Originally Posted by dosco

So what you're telling me is that when I'm driving on the highway in my '99 Camry and take my foot off the gas, that the engine is essentially "off?" Not sure I buy that because I would expect MUCH more engine drag and therefore deceleration.

It took me a while and a lot of discussions before I quite believed it. I assumed there would be more noise/vibration from the engine. However, if you think about it, everything is still running, there's just no fuel being injected.

Unless you have an extremely low top gear, there will be little drag just letting the wheels turn the engine. Think about all the torque required for the engine to turn the wheels in that gear; from the wheel's point of view, it's very easy to turn the engine.

This is why people trying to start the engine by rolling the car and popping the clutch use 3rd gear instead of 1st, and why you park a manual transmission in 1st instead of 3rd, 4th, or 5th.

The next question is how is it "easier" to use DFCO in a stick vice an automatic? Are you suggesting that one would downshift at highway speed to take advantage of the DFCO?

I've never feared shifting between N, D, 3, 2, and 1 on the highway. I've never driven a Camry, but I have driven a Tundra. I don't remember if I've tried it in the Tundra though I certainly wouldn't be afraid to. I seriously doubt Toyota would expose themselves to lawsuits and recalls to save five minutes worth of writing code or designing the valve body.

If it's a floor mounted shifter, you can probably move between D and N without pressing the button on the shifter. Consider that it's common for someone's elbow to accidentally knock it into N (as I once did in my mom's Ford Probe in 1988, scaring her since she was afraid to shift between N and D at highway speed); they would have required you to press the button if it was dangerous, as they require to shift out of P or from N to R.

However, I doubt that you'll need to at highway speeds unless your top gear is super tall. Below 1000 rpm is probably the point where DFCO quits, so as long as you're coasting in gear above 1000 rpm it's probably in DFCO mode. With an auto, if the torque converter isn't locked, then you'll have to coast faster to keep it above 1000 rpm than with a manual or an automated manual such as a SMT/DSG. I doubt there's any vehicle that won't keep it above 1000 rpm at 65 mph.

Sorry I can't answer any question about pulse & glide, I could only offer an educated guess. I need to learn about it too. I've intuitively done it sometimes, though.