Driving diesel car correctly.

CiniO

Hi.
I recently bought 2.2 civic diesel, which is in fact my first diesel car ever. I owned lots of car and travelled lot's of miles but they were always petrol.
So I'd have few questions in regards driving diesel and if I'm doing it correctly.

1. Engine revs. What are the correct revolutions to be cruising at to keep fuel economy high but not cause damage to the car? Is cruising at 1500rpm on 6th gear acceptable or is it too low? I understand that at those revolutions turbo doesn't kick in, so doesn't it make any damage to the turbo if it's not being used for several minutes travelling at that RPM?


2. Accelerating. At around 1600 - 1700rpm turbo kicks in, and you can really feel the power. However I heard, it's not got for diesel engines to step on the pedal to the floor at low revs like 1500 and below. Is that correct? Is it better to reduce a gear to jump revs to around 2000 and then start accelerating? Or maybe don't reduce gear, but just slightly press accelerator pedal, and only when it reaches above 2000 floor it? What do you think?
Example: I'm cruising on 4th gear at around 1600rpm (below 40mph) and I want to accelerate as fast as possible (f.e. overtake). What is the best option? Press the pedal to the floor, and wait until engine revs up to around 4000rpm, then change to 5th, and then again at 4000rpm to 6th?
Or maybe it's better to reduce from 4th to 3rd to make revs jump to above 2000, and then press the pedal to the floor?

3. High revs - is it OK for diesel engine to drive at high revs (f.e. above 3500rpm) for prelonged period of time? (I know petrol engines have no problem with driving at high revs for extended times, but what about diesels)?

4. Cooling down the turbo. I heard that after heavier driving you need to wait for a while after parking before you turn off the engine, so turbo has enough time to cool down. Is that correct? How long is it desirable to wait? Does it make any difference if car was driven gently with revs between 1500 and 2000, or rather raced to high revs just before parking? Does this waiting apply also to very short distance drives. F.e. I start the engine, and drive only for 1 mile. Do I have to wait before I turn off the engine? Is it generally OK, instead of waiting, to just drive it really gently for the last mile or so, not exceeding 1500rpm?

5. Heating up. Before the engine is heated up properly, especially in cold winter days, I heard it's not good to ride it hard. Does that apply to driving on high revs or just to really flooring it? I mean if it's -10 deg outside, can I just start the engine and start driving straight away, gently accelerating to about 2500rpm, or am I rather better to wait for a minute or two, and avoid exceeding 1600rpm so the turbo doesn't kick in for first few minutes?

6. Driving to the end of the tank. That's what I used to do. When amber light (low fuel) came in, I always driven the car until it was nearly empty and then refill up to the brim. Is it OK to do the same with diesel, or am I better fill'er up before amber light comes in?



Thanks for any feedback.

Henry Ford III

1/. Use the torque. Not sure where max. torque is on that Honda 2.2 but shift at/near it.

2/. As 1/. above. If the engine is warm and you are not labouring it you can use whatever throttle opening you wish.

3/. No. Most modern diesels will be pulling little more than 2000rpm at 120kph in top gear. No benefit thrashing it.

4/. Not necessary in normal driving.

5/. No high revs nor wide open throttle when cold. Applies to all engines really.

6/. Refill tank as soon as light comes on.

Bpmull

I've only ever driven diesels so ill give you my opinion on some of your points.
1. I couldn't see much problem with driving at low revs as long as you are not labouring the car. The turbo will always be spinning its not like it stops spinning at 1500rpm or anything. It just wouldn't be spinning fast/at full capacity until 1700 plus revs.

2. I generally have the car at about 1800 revs when overtaking that way your in the power band and change at 3500 rev max really I wouldn't see the point to going to 4000 revs as its out of the powerband at that stage and you'll get more pull acceleration by changing up a gear.

3. I personally wouldn't drive around a 3500 revs for a prolonged time there's no real need and you are increasing wear in the engine.

4. It is good practice to let a diesel idle for at least a minute or 2 before switching it off but I can't say I do this all the time but at least try and leave it a few seconds idleing.

5. You need to let the engine heat up. Ie just drive the car gently no harsh acceleration and change at 2000 revs just until it heats up.

6. Really when you let a car run low on diesel all it doing is sucking in all the crap particles at the end of the tank. Ideally try and fill up once the car drops below 1/4 tank. And i certainly would fill up the minute the light comes on. That's some of my thoughts on it hope its helps.

CiniO

Bpmull wrote: »

I've only ever driven diesels so ill give you my opinion on some of your points.
1. I couldn't see much problem with driving at low revs as long as you are not labouring the car. The turbo will always be spinning its not like it stops spinning at 1500rpm or anything. It just wouldn't be spinning fast/at full capacity until 1700 plus revs.

Allright. I thought it turns off completely below certain revs.
I'd bet though, that even at higher revs turbo speed depends on how much throttle is opened. It's like if I accelerate gently up to 2500rpm, turbo is nearly completely quite, while if I step on the gas, turbo can be heard spinning faster, even though in both cases I don't exceed 2500rpm. I assume this is normal.

2. I generally have the car at about 1800 revs when overtaking that way your in the power band and change at 3500 rev max really I wouldn't see the point to going to 4000 revs as its out of the powerband at that stage and you'll get more pull acceleration by changing up a gear.

There is this thing with 2.2 honda diesel, that it keeps it's momentum nearly to the end (4000) so I assume it's worth keeping up to that high rev if I want the best acceleration possible.
I don't do it often anyway.
What I'm more worried about is accelerating hard from low revs, as I heard it's not good for the engine. (possibly clutch and DMF get worn too much when turbo kicks in and there is this big kick in acceleration at around 1600-1700rpm. I love doing it and feeling this acceleration kick, but if it's bad for the engine I'll stop.

3. I personally wouldn't drive around a 3500 revs for a prolonged time there's no real need and you are increasing wear in the engine.

I travel through Germany few times a year, and I like to keep at around 200km/h for a good while if road conditions allow for it. That speed would require about 3500rpm, so that's why I was wondering if diesels are designed to last at those kind of rpms?
I know from experience, that properly serviced and maintained petrol engine shouldn't have any trouble to work at f.e. 5500rpm permanently for an hour or over.

4. It is good practice to let a diesel idle for at least a minute or 2 before switching it off but I can't say I do this all the time but at least try and leave it a few seconds idleing.

So it's not absolutely vital? Especially if I've driven gently for a while before stopping.

5. You need to let the engine heat up. Ie just drive the car gently no harsh acceleration and change at 2000 revs just until it heats up.

No harsh accelration is obvious for me, but I though that if turbo starts spinning fast at above 1600 maybe 1700, then it was completely not desired to exceed those rev's when engine cold. But from what you say, it seems to be allright to gently accelerate to 2000rpm and change to next gear. GOod.

6. Really when you let a car run low on diesel all it doing is sucking in all the crap particles at the end of the tank. Ideally try and fill up once the car drops below 1/4 tank. And i certainly would fill up the minute the light comes on. That's some of my thoughts on it hope its helps.

I'll do that then.

Thanks for the info.

RealExpert

I think you might be looking into this too much.................
Im not familiar with these cars but still common sense speaks for itself
This is what I do with my Renault Megane diesel.
Keep engine revs below 2000rpm as much as possible unless on the motorway.
When you are starting the car keep your foot away from the accelerater pedalneveruse the accelerater pedal like you would use it on a petrol car while cranking the engine.By letting it run for a moment before you drive away you are allowing the oil to circulate around the engine before revving it.
Dont rev the guts out of it theres no need.Dont believe all you hear or read a lot of it is over exaggerated bullsh** .On a frosty morning I let mine run for probably 15 or 20 mins before driving it.

Letting the tank run low in my opinion is no harm(unless there is a pump in it) Its not going to suck up dirt as most people will tell you because its too low.The dirt sits on the bottom of the tank and can be sucked up even when the tank is full of course there could be a little floating on the top as well and then if it went very low could also get sucked up and if that happens your filters will catch it.
Most important change the engine oil at recommended intervals and make sure its replaced with the proper oil.
Somone might disagree with me but thats what I do and I have diesel cars for 20 plus years

Crasp

1) drive it everywhere in the power band, except:

2) above ~120kph stick it in 6th

3) there's something to do with stopping a car with a turbo after a long drive... off the top of my head, if you pull off a motorway after prolonged speed, you can damage the turbo by just stopping the engine without letting the turbo cool down. So if you're planning on stopping, back off for a bit first to prevent damaging the turbo. This is just something I've been taught, don't know how accurate it is or the theory behind it...

4) another thing is to let the coils heat up before firing the starter. Just turn the key, let the lights go out, then fire it up. I'd do this always in any car in case any lights stay on.

Bpmull

CiniO wrote: »

So it's not absolutely vital? Especially if I've driven gently for a while before stopping.


No harsh accelration is obvious for me, but I though that if turbo starts spinning fast at above 1600 maybe 1700, then it was completely not desired to exceed those rev's when engine cold. But from what you say, it seems to be allright to gently accelerate to 2000rpm and change to next gear. GOod.


I'll do that then.

Thanks for the info.

I wouldn't really leave my car run too much after driving. Still don't rev it and then turn it off straight away switch it off as it idles. I often go to cork 2 hours drive without stopping when I get there I generally leave the car run for 30 seconds. Really it's just about driving the car nice and gently until it warns up. Try and keep it under 2000revs but then if your on a busy road you will have to get upto speed reasonably quickly. I'd say its more important to be gentle more so than the revs but try and keep it below 2000 revs.

As for the Germany thing I understand what you mean with the 3.5k revs thing I wouldn't be too sure tbh it's not ideal but I'm sure someone else may be able to help. As someone else said dont over think it. The most important thing IMO is not to drive hard when the car is cold as its just not good for the engine or turbo but the same could be said for a petrol to a lesser extend. Ultimately when the engine is cold the oil is too thick at the wrong viscosity to lubricate the engine and turbo properly that's the main problem really.

RealExpert

Crasp wrote: »

3) there's something to do with stopping a car with a turbo after a long drive... off the top of my head, if you pull off a motorway after prolonged speed, you can damage the turbo by just stopping the engine without letting the turbo cool down. So if you're planning on stopping, back off for a bit first to prevent damaging the turbo. This is just something I've been taught, don't know how accurate it is or the theory behind it...

I stand to be corrected here and this applies to all turbo charged engines.The reason you should not switch off the engine straight away after revving it is the turbo spins at an enormous rate and if you rev the engine and switch it off more or less straight away then the turbo is still spinning and there is no oil circulating inside it because the engine is switched off.
I think the reason is not to cool down as its cooled by the coolant but to slow down.

Ronnie Beck

I always do the first and last five minutes of a journey off boost. Usually I let it idle then for about thirty seconds before I knock it off. I only do this to let the turbo cool down a bit slower.

Example: I'm cruising on 4th gear at around 1600rpm (below 40mph) and I want to accelerate as fast as possible (f.e. overtake)

Here I would drop from 4th to 3rd, accelerate too 55mph, then straight to fifth.
Putting the foot down off boost is wasting fuel. It would be more efficient to use a lower gear and higher rpm.

Zcott

Saw your post over on civinfo too...;-)

CiniO

Zcott wrote: »

Saw your post over on civinfo too...;-)

Trying to get opinions from different sources, even if it's just copy and paste

Popoutman

There's less need to "cool" the turbos on diesels when compared to petrol engines, as there is a lot of airflow coming through the compressor as there's no throttle plate on a diesel. There's always a full cylinder's charge of air coming through the turbo. It's considered good practice to drive the last minute or two of the journey at light acceleration - but most of us do this anyway when parking. This reduces the amount and temperature of exhaust gas warming up the turbine section. Once you have 30 sec to a minute of gentle driving done that is all that's needed. No need to idle for any length of time.

The best way to drive a diesel:
To get best acceleration; shift to the next gear at the point at which the next gear's rpm is at the torque peak. This will not be the same for every gear.
When driving normally, drive with the engine rpms at the torque peak, as this is the most comfortable state allowing acceleration without changing gear and is generally the most fuel efficient state for the engine.
When driving like a granny, just don't allow the engine to labour, and don't use a lot of accelerator without dropping down a gear or two. This prevents the turbo from possibly operating outside of its design envelope, but most manufacturers shouldn't allow this state to happen anyway. Not good long term to drive like this as the oil pressure may not be enough to reach all parts of the engine causing premature wear.

In essence, if it feels right with the engine, it probably is.

deandean

Also, a modern turbodiesel benefits from a good trashing about once every full tank of fuel. Run it for a couple of miles at about 4000 rpm when the engine is fully up to temperature, preferably under load (going up a hill), this helps clear the crud out and helps the Cat and DPF.

Also, if your car has a dual mass flywheel, don't be changing up gears at very low revs, this is very hard on the DMF, better to get revs up to 1500+ when changing from first to second gear.

mickdw

Just drive the thing and dont trash it when cold.

Victor Meldrew

deandean wrote: »

Also, if your car has a dual mass flywheel, don't change up gears at very low revs,

most modern Diesels don't tolerate this anyway. They are easier to stall than their petrol counterparts. which is weird when you grew up on old diesels and then drove petrol for 10 years before running out of petrol cars to buy post 2008 (bloody greens....!)

Please Kill Me

Just recently bought my first diesel car after 23/24 years driving petrol cars. I was unsure about the points mentioned but was too embarrassed to ask. All good points taken on board, thanks all.