JocoJef

Lets just say I hit my red line 3 times before I stopped it. I was cruising down the road at 60 mph with my cruise control on, and saw a red light about a quarter mile up the road. So I canceled the cruise control by pulling the switch to me and then I threw it into neutral and coasted to the traffic. Well I never caught the traffic, and I went to turn my cruise control off because there was still traffic up ahead. Anyway, I accidently hit the cruise to resume (push up), while I was still in neutral. My rpms went to redline and hit 3 times until I put my foot on the clutch when it stopped because it deactivated it. Scared the crap out of me

So now here is my question.
1). Our car does not have a rev limiter in neutral? I thought that was in our car, and
2). Our computers do not recognize when our car is in gear and when it is not?

I think this is a huge flaw and I feel I should contact Toyota tomorrow about this. This has never happened to any of my cars in the past. Any insight?

ack154

iTrader: (7)

Most people don't cruise in neutral... so it probably functions as designed at this point. And I'm sure if there were problems with it, there would certainly be more reports of it by now. Was the clutch in or out?

For now I think I'd hold off on the "OMG WE'RE ALL GOING TO DIE B/C OF THIS HUGE FLAW I FOUND IN MY CAR" kind of stuff. Maybe a "hey, do you guys think this might be a bigger problem?"

But definitely keep us posted on what corporate says.

LiquidFX

I have never had it happen to me, I'll try it later.

JocoJef

clutch was not engaged (out). I'm not trying to say we are going to die, but if someone doesn't know about this and accidently does this, then motor could go boom

wolfe

On a modern car, coasting to a stop in neutral uses more fuel than if you slow down while still in gear anyway.

Mcfly315

I think the cruise system works the way it is suppose to. If you ever accidently activate cruise while in neutral, just step on the brakes, and the cruise acceleration will stop. It's kinda hard to fumble for the cruise controls but the brakes is a sure why to stop it. Hope you didn't damage anything.

Mcfly315

Wolfe....how does a modern car save gas while cruising to a stop in gear when the RPM is kept higher than in neutral? I always figured that when the car's RPM is high, the engine is burning more fuel. It might not be as much fuel as under full acceleration, but still buring some gas. Just curious?

dgHotLava

how do you figure this???
does not add up in my book.
N will use less fuel in more situations than not.

JocoJef

I hope I didn't either. No lights went on, and I don't hear anything out of the ordinary, thank god for a rev limiter atleast. I don't know why you would still be able to activate cruise control while in neutral

wolfe

I think the reasoning is that on a modern fuel injected car, it doesn't need as much (virtually no) fuel to keep the engine running since the wheels are turning it while coasting. I've seen several places state that a modern EFI engine all but cuts fuel delivery on decel.

There seems to be a lot of conflincting information on the web about this so I'm not sure how true it is afterall. I remember hearing this 'fact' a while ago on a review of a small hatchback car (saying that it used no fuel while coasting in gear) but don't recall if it was car specific.

Having had a better look online now and seeing all the conflicting stuff, I'd be interested to know for certain now.

There's a long discussion thread on it here: http://forums.tdiclub.com/showthread...1d5c3&t=138963

BIGRKtC

I call bullsh!$. This does not make any sense. While its true that slowing down in gear almost burns no gas, Its also true that slowing down in neutral burns absolutely no gas. When slowing down in gear, you have no foot on the acceerator therefore the revs are just caused from the forward motion of the car, not any gas air mixture causing combustion. However, I always say nuetral is better because, although it is tougher to on the break pads, pads are much cheaper to replace than the excess wear and tear on the engine and transmission caused by over-reving while using the transmission to slow down. But less gas than neutral, that's just fuzzy math! LOL

BIGRKtC

Well, rethinking this, I guess it would make sense if your saying that it takes more gas to idle the engine to keep it on while in neutral then it does for it to coast in gear. That could make sense.

Tomas

While slowing, in gear, with your foot off the gas, the ECU supposedly cuts off fuel to the engine (doesn't fire the injectors), so zero fuel is being used. The forward motion of the vehicle (inertia) is supplying the energy to keep the engine turning.

When idling with the clutch in or while in neutral, enough fuel has to be added to keep the engine turning.

P.S. Never 'resume' the cruise control with the transmission out of gear...

paultg

I still find this hard to believe, unless while slowing down in gear the ecu also cuts spark and fue completelyl. If not, then the motor would run lean and damage the cylinders when the spark happens, with no fuel.

I highly dought the ecu stops fuel all together, Things just dont work that way. The engine is kept moving by burning a fuel/air mixture. It might be a higher content of air and less fuel, but not "zero fuel". It just wouldn't work.

Paul G.

zer0

This is true because the engine uses more fuel to idle (while in neutral and coasting) than it does in gear and coast (due to the wheels spinning the engine.

http://en.wikipedia.org/wiki/Fuel_ec...uel_efficiency

azurTC

How much fuel is cut is determined by the deceleration enrichment programmed into the fuel injection by the programmer (Toyota). Most fuel injection cars have some sort or deceleration enrichment values in their maps, and spark shouldn't be cut if fuel is going in. How much or how little of each value is unknown by me.


^^^From the wikipedia page quoted.^^^

JOe

Tomas

Paul, since the same brain controls the injectors, sparkplugs, and valve timing/overlap, I see no reason why the ECU couldn't do whatever is needed.

(Also having a spark with zero fuel delivery is a unique incidence of 'lean' in that it is no different from having a spark in open air - no fuel is different than 'some fuel but not enough.' I would also expect increased valve overlap to reduce compression in some conditions - I.E. zero throttle and no brake 'feels' quite different than zero throttle, touch and release the brake - one appears to have considerably more 'compression braking' from the engine than the other. I use this effect quite often on the long, shallow hill on he arterial approaching my drive: Back off the gas, touch the brake, hold the posted speed solely with engine braking.)

The REAL answer is, "we don't know."

JocoJef

Hey guys, well this thread went off topic. Should our cars be doing this?

Tomas

Yes.

kytc

To me it would be no different than setting cruise to 100mph in 5th gear, slowing down, then reactivating cruise in 2nd gear, you're going to hit redline because the cruise doesn't know what gear you're in. I personally don't think it's a big deal.