Some technical questions....

[Tjkbeluga]

Have some technical questions for you guys

 

1) When driving down the slope at 70~90 kmh, I noticed that the auto gear sometimes seems to be at low gear. As such, when I release the accellerator, can feel that it will slow down. At this moment, if I change the gear to neutral, will it damage the gear? Mine is a CVT.

2) Is it advisable to heat up the engine before driving? Every morning when I go to the carpark, I do see some of them doing so.

 

Thanks

[Showtime]

1) You will damage your gearbox by doing so

2) No need to warm up. Just go easy till the temp reaches midway on the gauge.

[English5b]

1) Were you using D gear or lower gear (L or B)? If you feel "slowing down", that might be some engine braking when your CVT gearbox is in a relative low gear for 70-90 km/h.

 

No harm changing to Neutral but it is not advisable, not a safe way to drive.

 

2) No need to heat up engine, it is just wasting petrol.

[Cavver]

1) It act as an engine brake to the car, if you disengage to 'N' gear , you will lost engine brake, it is very dangerous especially @ down slope in such speed.

 

Changing gears from 'D' to 'N' wont damage your gearbox , but from 'N' to 'D' will.

[Cavver]

And also CVT has infinite gears ratio, so you dont really feel any 'jerk' in the gear change, so you will always feel that its stuck @ lower gear.

[Hamburger]

not sure abt CVT, but shifting to N in a torque converter autotrans will burn it

[Tjkbeluga]

I was at D, not lower gear. Hardly use the lower gear.

 

I know what you guys mean by engaging N gear and not having any brakes at all. Just that, coming from manual gear user, I used to have the habit of moving to free gear when approaching the traffic light and just use brake to slow down the car. In the case of my current car, sometimes travelling at expressway, after bypassing a slip road, it's usually going downhill because it's just after an overhead bridge. At that point of time, if I release the accellerator, I could sometimes feel that the gear slowing down the car. So I was thinking if moving to N could avoid this and move back to D again when I feel the car ready. But I guess like some of you guys said, moving from N to D could damage the car, I think better not...

[Cavver]

think nothing much you can do, cause the gear is decided by the systems. CVT is very much a culture shock to manual car users.

[Robo]

not sure bout CVT but for me thou i drive manual i tend to go down slower.. like 3rd gear no gas. once suddenly someone suddenly dash out from behind a van. gotta jam brake. thereafter i dont go fast liao. unless its at xpressway.. just maintain throttle at 5th gear.

[Showtime]

  Quote

No harm changing to Neutral .

 

most cars have a lock up which prevents you from engaging D when the foot brakes are not applied so as to avoid damaging the transmission. I would apply the same concept to the reverse process. ie only change to neutral when stationary.

[Dumb]

I have been changing from D to N and N to D while on the move for nearly 5 years. Nothing damage leh.

[Plexus]

  On 12/22/2008 at 3:59 AM, English5b said:

2) No need to heat up engine, it is just wasting petrol.

What about at least 30 seconds for the oil to start lubricating the parts? I used to wait till it warm up but true enough, it's wasting petrol.

[Cadbury24]

nowadays the engine designs allow the engine oil to run through the whole engine compartment immediately upon start up, thus no need for warming up. But it's still good to drive off slowly until the engine temperature reacehed its normal operating temp before you ram the engine..

[Cadbury24]

same here, my ride of 4 years is still working fine though i used to change from D to N, and N to D when on the move..

but I think it's even better if you can step on the pedal to achieve some rev on your engine if you're engaging from N back to D when your car is going fast, at least you won't jerk your fast-moving car with an idling engine, and damage the transmission in the process

 

  On 12/22/2008 at 8:25 AM, Dumb said:

I have been changing from D to N and N to D while on the move for nearly 5 years. Nothing damage leh.

 

[Pisces69]

  On 12/22/2008 at 4:47 AM, Tjkbeluga said:

I was at D, not lower gear. Hardly use the lower gear.

 

I know what you guys mean by engaging N gear and not having any brakes at all. Just that, coming from manual gear user, I used to have the habit of moving to free gear when approaching the traffic light and just use brake to slow down the car. In the case of my current car, sometimes travelling at expressway, after bypassing a slip road, it's usually going downhill because it's just after an overhead bridge. At that point of time, if I release the accellerator, I could sometimes feel that the gear slowing down the car. So I was thinking if moving to N could avoid this and move back to D again when I feel the car ready. But I guess like some of you guys said, moving from N to D could damage the car, I think better not...

====================

 

The "engine braking" effect is good as it gives u more control of the car as u go downhill. The engine brake wil slow u down a little & u can increase the braking by gently using the foot brake. If u need to go faster, just press gently on the accelerator.

 

The new autoboxes r designed with this feature which was missing in many older autoboxes. We had to manually shift to gear "2" or "L" to have the desired engine braking.

 

Just leave it in "D" as its a good safety feature to have. I doubt u wil consume more fuel as the RPM climbs as the injectors r not really pumping more fuel into the cylinders. Even if they do pump in slightly more than when at idle, its good cos the fuel is helping to cool & lubricate the upper cylinders.

 

As for warming up a cold engine, not really necessary with modern fuel injected engines. The ECU is already running the fuel "rich" to quickly warm up the engine. Nowadays everything is automatic & so easy compared to many years ago when u had a MANUAL choke which u had to control yourself.