Is My Avensis Too Thirsty

[BALIKBAYAN]

Hi everyone,

I bought an T25 Avensis estate from 2004 with the 2 lit D4 1AZ-FSE engine in September and I sold my CarinaE because it had became too old and the rust was coming fast on it. I expected to get a bit higher fuelconsumption on the Avensis than the Carina, but I believe it is too high. I am just below 30 mpg or 9.5 lit /100km. I still drive the same way as I did during the time I had the CarinaE. You can look at my profile at fuelly.com. I have the same username there as here.

Do I have a normal fuelconsumption or not?

[Heidfirst]

the cold hits diesels worse than petrols so mpg at this time of year will be noticeably down.

This is especially true if you are just doing short journeys where the engine never really warms up.

Under 30mpg sounds poor though but more info needed re. the type of motoring that you do.

You might want to check your filters are clean though.

[BALIKBAYAN]

Mostly I drive rather short journeys, but I did that before with the Carina too. I doubt that the filters are dirty. The filters and oil was new when I bought the car in September.

I have less than 2 km to the motorway and then it is motorway for almost 10 km and then I have about 4 km to work. I drop the son at school before the motorway too. Most of the driving is like that. I have almost the same kind of driving when going to the shopping centre outside the town too as I have when I drive to work.

[Heidfirst]

does your car have a DPF (I believe that Toyota introduced D-CAT late 2003)?

[BALIKBAYAN]

What is DPF?

[Heidfirst]

Diesel Particulate Filter - in Toyotaspeak D-CAT.

These work by injecting fuel in to burn off the trapped particulates & as such use more fuel than cars not so equipped.

I think that a 2.0 D-CAT of that age would be quite rare in the UK but they should exist.

[t-spiritpete]

What is DPF?

This explains most of it,

"Clean" diesels? Toyota's D-Cat and DPNR

Old-school diesel engines used to sound like tractors when you started them on a cold morning, and they used to spew particulates out of the exhaust to the point where the back of the car went black. Newer generation diesels start much less noisily but for the most part still have some issues with particulates in the exhaust. Toyota claim to have solved this with their D-Cat and DPNR system. D-Cat stands for Diesel Clean Advanced Technology and DPNR stands for Diesel Particulate NOx Reduction. The operating principle is fairly sound. D-Cat is an advanced computer-controlled system for cleaning diesel exhaust gasses which relies on the DPNR catalyser. This is a combination of particle filters and normal gas-reduction catalysing metals that remove particulates, sulphur dioxide (SO₂) and nitrogen dioxide (NO₂) from the exhaust gasses. A sensor measures can tell when these filters are nearly full at which point a fifth diesel-injector sprays a little fuel directly into the exhaust system. Combined with the exhaust gas recirculation system, this results in all the collected pollutants being burned off, cleaning the filter in the process. DPNR requires ultra-low sulfur diesel (ULSD) to work properly.

Shortly after this system was launched on the D-4D engined 2.0litre Toyota Avensis, the complaints started to come in. Notably, Dutch car magazine AutoWeek (issue 42 / 2006) exposed the problem when their DPNR-equipped Avensis started driving around with a huge cloud of white smoke pouring out of the exhaust. They weren't the only ones to have this problem. Hundreds of complaints were filed in Germany and other European countries for the same thing. The problem was that the D-Cat/DPNR system needs to 'regenerate' as described above. The particulate and gas filters are cleaned via a combustion mechanism in the exhaust, but this only happens at speeds below 160km/h (99mph), and takes about 20 minutes each time. In Germany especially, where they still have sections of unlimited-speed autobahns, people had been driving well over that speed for miles on end, then stopping and turning the car off, only to repeat the cycle twice a day during their commute. When this happens, the DPNR system never gets time to regenerate normally and the particle filters become clogged and the DPNR system forces a clean cycle to happen. This forced combustion results in white smoke as there are too many pollutants trying to be burned off at the same time. And not just a little white smoke. In the AutoWeek test, they thought their Avensis was on fire it was trailing so much smoke. Toyota promised to sort this problem out with an improved version of D-Cat fitted to the higher-spec 2.2litre engine.

Read more: http://www.carbibles.com/fuel_engine_bible.html#ixzz1gdhuQAIj

Pete.

[cabcurtains]

Diesel's and short journey's don't go, the car will not be warm as it takes about 5-10 minutes and will be effectively running on the choke (the modern version) which will burn fuel quicker.

I think the car will be a D4D, werent the D-Cats very rare compared with a D4D on a 2004?

[Heidfirst]

As I said I think that a 2004 D-CAT 2.0 would be pretty rare in the UK but they are supposed to exist so it's worth asking the question.

[BALIKBAYAN]

It is a petrol engine. 1AZ-FSE is a 2.0 lit direct injection (D4) petrol engine with variable valve timing on the intake. I believe they have put an i in the variable valve timing too (vvt-i) as it sense the temperature and lot of other things too. I am worried about the valve timing valve. If that doesn't work the valve timing will not work and then the engine might be very thirsty.

[cabcurtains]

What a bunch of assuming doughnuts we are

I think just under 30MPG when used on short distance's with a 2.0 Petrol sounds reasonable to me.

[Jas16]

nothing wrong there, perfectly fine :)

[BALIKBAYAN]

OK, thanx.

[BALIKBAYAN]

I have done some longer trips with the car lately. I have improved my fuel consumption. Now I have between 7.6 and 7.9 lit/100km when I am doing a longer journey. I have also noticed that it do get thirsty if I go above 3000 rpm. That means it will be difficult to keep the right speed at motorways and still have good fuel economy. If I drive between 70 and 100 km/h (80 km/h is about 50mph) it has very good fueleconomy. It feels like the engine and transmission is not a perfect match. Today when everybody need to think about the environment the lowest fuel comsumption should be in a speed you can use on the motorways too. Maybe it should be a 6 geared box instead?