Mazda Diesels

Padwick

I've recently upgraded (or so I thought) from a Mazda 6 1.8 petrol to a Mazda 6 2.0 TDi, as I could not keep fuel in the petrol one. The only problem is that the fuel guage is dropping a lot quicker in the diesel one than it ever did in the other. I read a lot of reviews and never seen anything to say that they had a reputation for poor fuel economy like the petrol has.
Anyone know what may be causing this; something I need to get done or a part that needs changing. I know nothing about diesel cars. Or is this just a problem that these cars have? I don't expect it to be too economic, being a 2 litre turbo diesel but I did expect it to be better than the petrol model seeing as the spec is 47mpg (diesel) as opposed to 34mpg (petrol).
Thanks in advance for any suggestions.

mike65

Silly question maybe, but how do you drive? All right foot?

Mike.

unkel

The diesel is 140KG heavier, but you should still see a significant saving in fuel consumption. Did you actually measure your mpg (or l/100km) on both?

Padwick

I've not done a full tank yet but I've done around 190 miles in it and it's used a good bit over half a €68 tank of diesel (106.9 per liter when filled). I was getting 400 miles out of a tank in the petrol model (107.9 for the petrol in the same garage I use).
I'm not driving it badly (as far as I know anyway). Around 160 of the 190 miles have been 70mph motorway driving in 5th.

mike65

Does the car have a trip computer? Some gauges are less than 'linear' in the representation of fuel used up.

Mike.

Padwick

If you mean the liter/100km then yes there's a display but I'm not sure how it works. All I know is that I've an 80 mile spin ahead of me tomorrow and the way it's drinking, I'd be afraid to chance it on 1/3 of a tank.

Woah!I sure hope not because I want one of those! I have it from another mazda owner that the average 52mpg. I would give a dealer a ring and ask if it is normal.

maidhc

Is this the 2.0 HDi engine as found in the 407, Focus and and Volvo?

Padwick

Moonbaby wrote:

Woah!I sure hope not because I want one of those! I have it from another mazda owner that the average 52mpg. I would give a dealer a ring and ask if it is normal.

I bought it in a garage that wasn't a Mazda dealers though. Anyone know where I can find specs online for the 2003 model? I can only find them for the newer 2005 one online.

maidhic wrote:

Is this the 2.0 HDi engine as found in the 407, Focus and and Volvo?

It's the 2.0TDi 136BHP version. It's a 2003 car.

unkel

maidhc wrote:

Is this the 2.0 HDi engine as found in the 407, Focus and and Volvo?

It's a diesel developed by Mazda themselves (DIRECO-D), so not PSA (HDI) or Ford (TDCI)

Padwick

I've just checked the in car display and the CONSUM AV (average fuel consumption performance since it was last reset - before I bought it) is 9.6 L/100km. I've no idea what that means but I'm hoping someone can tell me. In the meantime I'll try a Google search for a conversion to MPG.

Padwick

Just found a converter and 9.6L/100km is 29.4 miles per gallon. That is absolutely horrendous for a diesel. So that'd tell me there's a problem anyway.
Any engine buffs know what I can get checked on the car?

unkel

Padwick wrote:

Just found a converter and 9.6L/100km is 29.4 miles per gallon. That is absolutely horrendous for a diesel.

Yes I'd expect that for a 1.6 / 1.8 petrol that does quite a bit of city driving. Here's what you need to do to find out for sure what the consumption is:

Fill up the tank completely today. Reset your distance to zero on the dash. Drive in your usual way until the tank is nearly empty. Fill up the tank completely again and calculate your consumption

No use basing it on possibly inaccurate in-car computers or worse, on driving by the previous owner. Let us know what the results are

Padwick

I will indeed. I'll let you know what it turns out as.

johnnyrotten

I have a new 06 1.6 TDi Madza 3. Its absolutlely brillaint on Fuel economy.
For example:
Did a run to Warrenpoint Co.Down yesterday ( 230 Kms ) and used under 1/4 tank of diesel ( €48 fill)

Padwick

I've filled mine and done 467 miles since then. I'll be filling it again tomorrow morning so I'll post the amount of liters it takes to do so. Not looking too promising though, as it costs around €70 to fill (going by the petrol car I had).

AlanD

I really don't understand why people estimate the fuel consumption of their car based on how far they get with €50 or some other monetary figure. It's about as scientific as putting a wet finger in the air to see if it's night time.

The most accurate way is not just to fill the tank to where you think it's full, but fill it up to the neck so you can see the fuel level at the top of the neck. It'll take that extra few minutes and you may not get a nice rounded euro amount to pay, but it's the right way to do it. Reset your miles or kilometres, do your drive, no matter how far. You don't have to empty the tank, although it's best to do several hundred miles to be accurate. Fill again up to that same visible point, noting the exact number of litres it takes to fill back up. What is this figure? It's the exact amount of fuel your car needed to drive x amount of miles. Do your maths and you'll get pretty accurate MPG.

Also, the speed that your needle moves while driving is also as scientific as said wet finger above. Different car, different tank. Do only as stated above and you will find out whether or not your car is drinking juice.

That 136bhp engine should get between 40 and 45 mpg I figure, although you'd get close to 50 if you drive like Miss Daisy.

Hope it works out for you!

Big Nelly

Padwick wrote:

I've filled mine and done 467 miles since then. I'll be filling it again tomorrow morning so I'll post the amount of liters it takes to do so. Not looking too promising though, as it costs around €70 to fill (going by the petrol car I had).

The main problem here could be how you drive, are you putting high revs on the car before gear changes? driving like a head the ball? what type of driving are you doing, city or long roads?

Just got my 02 Passat and when Im in Dublin city the onboard computer says I am running about 35-40Mpg, went to Cavan at weekend and was getting 45-47Mpg, came back up and used the cruise control all the way up except in towns. Was getting over 55Mpg:D

Padwick

AlanD wrote:

I really don't understand why people estimate the fuel consumption of their car based on how far they get with €50 or some other monetary figure. It's about as scientific as putting a wet finger in the air to see if it's night time.

The most accurate way is not just to fill the tank to where you think it's full, but fill it up to the neck so you can see the fuel level at the top of the neck. It'll take that extra few minutes and you may not get a nice rounded euro amount to pay, but it's the right way to do it. Reset your miles or kilometres, do your drive, no matter how far. You don't have to empty the tank, although it's best to do several hundred miles to be accurate. Fill again up to that same visible point, noting the exact number of litres it takes to fill back up. What is this figure? It's the exact amount of fuel your car needed to drive x amount of miles. Do your maths and you'll get pretty accurate MPG.

Also, the speed that your needle moves while driving is also as scientific as said wet finger above. Different car, different tank. Do only as stated above and you will find out whether or not your car is drinking juice.

That 136bhp engine should get between 40 and 45 mpg I figure, although you'd get close to 50 if you drive like Miss Daisy.

Hope it works out for you!

I'm hoping it does do over 40 anyway. Would be a real waste of the extra I paid for the car if it did less.
The €70 I mentioned is only an approximation. I am putting enough in to completely fill the car as you mentioned, no matter what the monetary value.

Big Nelly wrote:

The main problem here could be how you drive, are you putting high revs on the car before gear changes? driving like a head the ball? what type of driving are you doing, city or long roads?

Just got my 02 Passat and when Im in Dublin city the onboard computer says I am running about 35-40Mpg, went to Cavan at weekend and was getting 45-47Mpg, came back up and used the cruise control all the way up except in towns. Was getting over 55Mpg

1000-1500 revs before gear changes. I'm around 85% open road (with cruise control - is it better or worse to use this?) and 15% towns/cities. I'm never driving like a maniac (never more than 5mph over the speed limit).

Big Nelly

Padwick wrote:

1000-1500 revs before gear changes. I'm around 85% open road (with cruise control - is it better or worse to use this?) and 15% towns/cities. I'm never driving like a maniac (never more than 5mph over the speed limit).

Cruise control is putting an extra 5-10Mpg on my Passat so it seems to run better if you use it, only have car a while so only got chance to use cruise control on open road at weekend, Im change at around the same revs as well

Padwick

Big Nelly wrote:

Cruise control is putting an extra 5-10Mpg on my Passat so it seems to run better if you use it, only have car a while so only got chance to use cruise control on open road at weekend, Im change at around the same revs as well

I had it at 72 for the whole stretch of the M1 the other night (bar the tollbridge) and the L/100km was the best I've ever seen it.

Big Nelly

Padwick wrote:

I had it at 72 for the whole stretch of the M1 the other night (bar the tollbridge) and the L/100km was the best I've ever seen it.

Yeah would love a nice spin on M1 or M50 to let it run for a long distance to see how it would run, on the N3 would only have it on a while and then would need to flick off as I hit a town

Padwick

Worked out at 43.9mpg.

greglo23

43.9 is'nt bad but the first thing i would do is check the air filter as a dirty filter has a bad effect on economy.

Padwick

greglo23 wrote:

43.9 is'nt bad but the first thing i would do is check the air filter as a dirty filter has a bad effect on economy.

I'm going to get that looked at.
I've done the second run now too. I've put the miles travelled from full and the liters (gallons) to refill the tank afterwards.

1: 460.7 miles - 47.7 liters (10.49 gallons) - 43.9 mpg.
2: 388.8 miles - 39.4 liters (8.67 gallons) - 44.8 mpg.

Happy enough with that to be honest as a Mazda dealer I rang said that my model should be doing 43 or 44 mpg.

JohnBoy

unkel wrote:

It's a diesel developed by Mazda themselves (DIRECO-D), so not PSA (HDI) or Ford (TDCI)

are you sure?

surely it's the same engine as found in the mondeo, given that the six shares it's platform with the mondeo.

no methinks its a HDI alright

maidhc

JohnBoy wrote:

surely it's the same engine as found in the mondeo, given that the six shares it's platform with the mondeo.

no methinks its a HDI alright

The mondeo doesnt have a HDI, but a Dagenham engine which it shares with the Transit. Ford and Pug have been working together on diesels for a good few years now anyway, so i presume there is a lot of component sharing.

I would have thought the mazda would have had something from the ford parts too, surprising they keep a third 2.0 diesel going.