Throttle Lag On DBW

[hatchbackkid82]

I really don't notice it

[bronsin]

Originally Posted by Yaris Hilton

Whenever you're coasting with the engine turning much above idle speed, the fuel is completely cut off for zero emissions and zero fuel consumption.

If that were true the engine would stop running. The engine has to have fuel to idle. But what you say is interesting. I had a BMW F650 2001 which, at times, would not idle when you came to stop at a light. It would start and run if you gave it more throttle while cranking, but it would not idle if you relaxed the throttle to the idle position. Turn the ignition off and on, start the engine and poof, it ran flawlessly. Until the next time. I could not fix it and neither could BMW. (their main effort was to blame me for not pulling the clutch in in time)
But maybe it had something similiar to what you describe. Thats the problem with all this gee whiz neato stuff. When it breaks its pretty hard (if not impossible) to fix. Some say they dont notice this problem so maybe theirs is working properly.

[marcus]

i-stop technology is coming in 2011..some cars in europe has it already.

[kenora]

Originally Posted by Yaris Hilton

I don't think my daughter's '01 with AT did. (At least in "Drive.") But you'll be able to feel it if it does. It's really pretty subtle, not a great lurch. You have to pay attention to it.

Mine definately does it and it took awhile to realize what was going on, its most noticeable with cruise on coasting down a slight decline around 60 kph, it will accelerate (going down hill) just a bit to a speed which is above the set speed (60) then go off throttle, that causes DFCO to kick in, it decellerates to a speed just below the set speed and wants to speed up so DFCO is cancelled, fuel flows again and car speeds up to set speed at which point with the engine running it goes a bit over the set speed and DFCO cuts off fuel. The process continues until either the hill gets steep enough that it can stay in DFCO at or above the set speed or I get in the flats and the engine runs as normal.

Pretty subtle but you can "feel" it cut in and out.

[Yaris Hilton]

Originally Posted by bronsin

If that were true the engine would stop running.

Not at all. It's engaged to the driveline and is kept turning by the car's momentum. Indeed, if you turn the switch off with the car in gear and moving, the engine will keep spinning till the car eventually stops.

DFCO is very common in modern automobiles.

The fuel cuts back in at idle power level when the engine speed gets down to some preset level just above idle.

[Tamago]

Originally Posted by Yaris Hilton

Not at all. It's engaged to the driveline and is kept turning by the car's momentum. Indeed, if you turn the switch off with the car in gear and moving, the engine will keep spinning till the car eventually stops.

DFCO is very common in modern automobiles.

The fuel cuts back in at idle power level when the engine speed gets down to some preset level just above idle.

i'd like to add that this only happens on decel (per my wideband o2 anyway)

[cali yaris]

If that were true the engine would stop running. The engine has to have fuel to idle.

Actually, you're right. But in DFCO, the engine isn't "running" or idling, it's just spinning. There is no spark and no fuel during DFCO.

Tamago, the "D" stands for deceleration, so it's clear that's when it happens.

[RedRide]

I don't notice any throttle lag at all with my new Yaris with a manual tranny.

What was described in the original post seems like a defect IMO. It is not only anoying but, downright dangerous as well!
If it was me, I would go to the dealer and report the problem ASAP.

Not having access to 100% WOT on demand is a real problem as far as I'm concerened.
Perhaps as previouslty alluded to in other TBW threads, the less than 100% throttle is a setting for those who drive for economy while more aggresive settings are achieved for those who drive for performance?

I do know that my Celica (with a cable throttle) is set up in a simular way and will tune its self acording to your driving style. I frequently have to go for WOT, etc. otherwise, it will start to tune itself for more economy and less performance.

[Zaphod]

It's just compression braking with no fuel, as the drive train is turning the engine and pumping air through it.

What gear you're in determines the RPMs that your engine is running at, which determines how much air is being pumped through the engine, which is the resistance that slows the car down.

It's pretty easy to get used to judging distance and timing compression braking pretty much the same as you would with your friction brakes to the point that you use a lot less friction to slow down (and less gas with DFCO).

Honestly, I've noticed the lag with drive by wire more starting out in first on a hill. The workaround for me was to give it more acceleration earlier than I normally would with a manual transmission.

[Tamago]

Originally Posted by cali yaris

Tamago, the "D" stands for deceleration, so it's clear that's when it happens.

and how does this work on an automatic? sounds highly inefficient as the engine revs will drop off, torque converter goes jellylike and now you have to build all of that energy back up to get the car moving again. i guess on a super long decel it would save fuel but otherwise not really ?

[cali yaris]

sounds inefficient the way you describe it, but I'm sure Toyota considered options and built something for optimum mileage, don't you think?

[bronsin]

Originally Posted by Yaris Hilton

Not at all. It's engaged to the driveline and is kept turning by the car's momentum. Indeed, if you turn the switch off with the car in gear and moving, the engine will keep spinning till the car eventually stops.

DFCO is very common in modern automobiles.

The fuel cuts back in at idle power level when the engine speed gets down to some preset level just above idle.

Hmm you said "turn the (ignition?) switch" off. I agree it would stop. But we're talking about taking your foot off the gas pedal and supposedly the fuel is cut off. If I took my foot of the gas of my Yaris it would slow down sure. But it would eventually go about 5 mph, not stop.

[bronsin]

Originally Posted by RedRide

What was described in the original post seems like a defect IMO. It is not only anoying but, downright dangerous as well!
If it was me, I would go to the dealer and report the problem ASAP.

I agree! Unfortunately my wifes 05 Camry does the same thing. So we went through all this four years ago with the dealer. They couldnt fix it. I think it IS dangerous or at least undesireable. But you adapt to it I guess. The safety people could declare a recall but I doubt the company could do anything about it. Some claim their Yaris doesnt do this. Id like to try one out. If it didnt boy I would say the government should issue a recall notice. But in my experience the company couldnt fix it.

[alhope34]

Originally Posted by bronsin

Hmm you said "turn the (ignition?) switch" off. I agree it would stop. But we're talking about taking your foot off the gas pedal and supposedly the fuel is cut off. If I took my foot of the gas of my Yaris it would slow down sure. But it would eventually go about 5 mph, not stop.

That's because DFCO only works above 1100 rpm, or around there. Once you get below that rpm, it starts putting gas and spark back to the engine so it wouldn't stall. Obviously it would be a marketing horror to try and sell a car that stalls every time you take your foot off the gas. My Mazdaspeed 3 also has DFCO and I can never feel any difference when it goes on or off.

[bronsin]

Originally Posted by alhope34

Obviously it would be a marketing horror to try and sell a car that stalls every time you take your foot off the gas.

My 2001 BMW F650 motorcycle, thankyou very much BMW!

[Tamago]

Originally Posted by bronsin

My 2001 BMW F650 motorcycle, thankyou very much BMW!

shoulda bought an R bike

[Tamago]

Originally Posted by bronsin

If I took my foot of the gas of my Yaris it would slow down sure.

i think this deserves a captain obvious award.

[alhope34]

Originally Posted by Tamago

i think this deserves a captain obvious award.

Ahahaha, agree'd!