Greetings, first post and all.

Over the last two weeks of ownership I have noticed that the i30 Diesel manual prefers warmer temperatures for fuel economy.

When the ambient air temperature is over 20 degrees C during the day, I can attain 3.8lt/100km for 500km.

Yet when the ambient air temp is below 5 degrees C at night, I can't get any better than 4.5lt/100km for 500km.

This is on the same road, driving exactly the same way, same traffic conditions, over the same tank of fuel.

I've pulled up at night, opened the bonnet and felt the top of the intercooler, it was freezing cold. (Inlet pipe at the bottom of the intercooler was warm to the touch)

Anyone else notice this happening? Cold weather hurts fuel economy in the i30 diesel?

Also, found that the high beam is lacking on country roads, so I installed 35w HiD on the low beam, 50w HiD on the high beam. Perfect for driving at night now.

Mods so far, LED interior lights, 120GB USB hard drive, HiD headlights, window tint, debadged.

Few more mods to come, LED tail lights, HiD fog lamps (3200k), full body kit.

Hi Thumper,welcome to the forum :00000732: It's very interesting that you found the fuel economy affected by temperature. Did you have the heater on? I thought heater wouldn't affect a lot on fuel consumption like the air-con do. Anyway, there's a lot of diesel owners here so I think they will find it's very interesting too.

LED tail lights look very nice (from koreaimport) I really like to have them installed but I'm not sure if it will have any effect on the i30 whole electrical system. I'm also worried if it can give a good seal from water and moistures like the original one. Please keep us know your experience with the LED tail lights :)

[quote=Thumper,May 17 2008, 10:14 PM]Greetings, first post and all.

Over the last two weeks of ownership I have noticed that the i30 Diesel manual prefers warmer temperatures for fuel economy.

When the ambient air temperature is over 20 degrees C during the day, I can attain 3.8lt/100km for 500km.

Yet when the ambient air temp is below 5 degrees C at night, I can't get any better than 4.5lt/100km for 500km.

This is on the same road, driving exactly the same way, same traffic conditions, over the same tank of fuel.

I've pulled up at night, opened the bonnet and felt the top of the intercooler, it was freezing cold. (Inlet pipe at the bottom of the intercooler was warm to the touch)

Anyone else notice this happening? Cold weather hurts fuel economy in the i30 diesel?

Hi Thumper, great mileage mate, i have only had my i30 about two or three weeks? i just got home from weekend away i traveled 1,040 k's on the one tank still showed 1/4 of a tank left i filled to the top like i did b4 i left, took me a while but i got it right to top both times and got 45Lt's in the tank after 1,040k that was over the blue mountains via katoomba then out to Dubbo then back to near Mudgee then out near Dubbo again down golden HWY VIA MuSTLEBROOK then down the putty road to Windsor then out to Hoxton to see someone then along the M7 then M2 to home covered 600k today and fill up at same servo as on friday. so happy as motor only done 2,200K. i would expect warm weather to give best mileage.




This post has been edited by Lakes: May 18 2008, 03:02 AM

:00000732: Thumper (had a rabbit once called that - but I digress....)

Not happy Jan... that would explain why I can't match "warm weather Bob from S.A." I'm using about .5 litres more than he is per 100km...

In that case they are going to have to sell them for $500 cheaper in Tasmania than the "North Island" by my calculations to offset the difference in economy over the life of the vehicle... I'm off for a part refund... :P

Rgds,

Dazz

P.S.

Can we have some pix and more details about your mods please either here or here...

http://i30ownersclub.phpbb88.com/

This post has been edited by dazzling_darryl: May 18 2008, 03:16 AM

Hmmmm... Thats interesting, Should be the opposite as diesels like cooler air & thats why they have intercoolers. Hot air is less dense than cool air. So you have a lower mass of air in a certain volume when it’s hot than when it’s cool this increases the mass of air that is put into the cylinders, hence greater mass of air available to combust fuel and therefore more power.

:00000732: Thumper.

Are you Stephen Hawking in disguise?

So what you are saying 130CRDi is that my i30 might use more fuel than Bob's but it's probably because the extra power makes me drive quicker... :whistling:

I have always got better mileage in summer with petrol motors too.
but just from interest what weight oil are you useing Thumper?

Thumper,

I'm interested in finding out more details of your HID glone upgrades. When you have the time, could you enlighten us more.

Bob

Greetings all again. :)

Ok, my i30 is factory stock, nothing done to the motor side of things, yet. :whistling:

Stock oil, stock air cleaner, stock exhaust.

As for heater/air con, I had the heater on at night, yes, but did not have the air con on during the day. (Made sure of that)

I'll be driving down to Cooma, then to the coast tomorrow and will be testing blanking off the intercooler, so no air can go through it from the front. Hopefully this will allow warm air to enter the engine.

Yeah, doesn't make sense to me either, 15 years of racing cars and building engines (V8 GT Falcons, Mini Coopers, turbocharged Daihatsus) this is the first time I have found cold weather to affect a vehicle this way.

When it's warm outside, the i30 goes like a rocket. When it gets cold outside, it feels sluggish, slow to respond to throttle changes.

As for the lighting mods, I have posted pictures on the other site. :)

For those who want a sneak peak:

(IMG:http://img522.imageshack.us/img522/2743/10045731vm1.jpg)

Thumper, what diesel fuel are you useing? if you look at the BP sight they say they use different fuel summer to winter, not sure if the others do to, and not sure if that effects mileage. reason i get better mileage summer in petrol is fuel expands when its hot. but this is my first diesel i have owned.
a mate that is a farmer that i called in to see told me the weight of the oil effected his common rail turbo diesel 3.0Lt said it was hard to start in winter when he used 15 40, had to go down to 5 30 said something to do with the way his motor is set up from factory.
i noticed the lights are not that good in coutry at night too.

Using diesel from the same service station (independent local servo) that is a winter blend. (Has been for the last month, so that is all I have been using)

As for engine oil, same that came with the vehicle, haven't touched it. Starts perfectly fine on cold mornings.

Ok, did a test this morning. -2 degrees C ambient air temp, fuel economy was the worst I have ever seen. 5.2lt/100km at a constant 100km/h for 150km.

I had made a cover that goes over the front of the intercooler, so pulled over, fitted the cover (Stops outside air passing through the intercooler) reset the average lt/100 on the trip computer. Let the beast idle for about 10 mins (Was answering a phone call) felt the top of the intercooler, it was now warming up. (Was very cold when I pulled up)

Off I go, constant 100km/h for the next 128km.

Guess what my economy was? 4.2lt/100km for the rest of the trip.

Pulled over, opened the bonnet, felt the intercooler, top and bottom the same temp. (Warm, not too hot, could hold my hand on it for an extended period of time)

Interesting to note, when there was no cover on the intercooler and ambient air temp was -2 degrees C, the beast was sluggish off boost, slow to respond to throttle inputs.

After the cover was fitted, ambient air temp now around -1 degrees C, after a little bit of driving, instant response to throttle changes, no more sluggish engine off boost.

I'm going to leave the cover inplace when the outside temp is below 10 degrees C for a while to see if it's just a coincidence that economy gets better when I allow the intercooler to stay warm.

I will be fitting two thermo couplers to the piping, one on the outlet of the turbo, the other, on the top (Outlet) of the intercooler, recording the temperatures encountered.

Thus far, I believe that cold weather, light running, harms fuel economy in the i30 diesel. (It prefers warm ambient air)

As for the high beam, absolutely perfect now. Just like having a set of high powered spot lights! :)

Thumper,

I always find the i30 sluggish when it first starts up. Until it is at running temp, like all diesels, it needs to be nursed along.

Can you try this for me please. When the engine is warm, one day try driving with the air cover on for a stretch of road and measure the fuel consumption. Repeat with the cover removed on a day with similar temperatures and see what the difference is. Both tests need to be done with the engine warmed up though. This will test your theory and prove it or disprove it one way or another.

Bob

Sorry, this is what I did. Started the beast, warmed it up, then drove for 150km. (I am sure it would have been warm by then! :) ) It warms up in about 2km from home. It is sluggish even after 100km of driving.

I then pulled over, fitted the screen to the intercooler, and then continued on, after letting it sit for for a few minutes, idling. I reset the average lt/100km, the went on my way. The sluggishness is gone, economy is allot better.

Both times engine was warm, both times same altitude, both times almost the same ambient outside temp (-2 to -1 degrees C) same driving style, same type of highway. Same tank of fuel.

Only way I can be 100% sure that cold air affects the i30 diesel engine is to fit a OBD II scanner to the engine and map the duty cycle of the injectors, watching the difference when ambient air is warm, and when ambient air is cold. If the duty cycle of the injectors increases, then I know for sure that the i30 is increasing fuel to help keep the engine warm.

I know, this might be a small thing, but it is driving me crazy, because I purchased the i30 diesel knowing it was one of the most fuel efficient vehicles available. :thumbsup:

Thumper thats good to note, i have never driven in lower temps than about 10 or 11c yet.
with petrol the intercooler allows them to run more boost with same fuel.
i have an air sensor that i can run if i weld a bung on the pipe, but will have to check if it can run with diesel, i can put it on my v8 and go for a dive and play it all back on PC with all the hook ups it gives a lot of information.

This post has been edited by Lakes: May 19 2008, 06:22 AM

Gday Thumper

That is impressive reduction in fuel use with the blocked off intercooler of 1l/100km :thumbsup: I would like to know if there is any improvment to be had at high air temps like 20-25 degrees c if you get round to testing that.
Maybe these cars have great economy lock up in them with some simple mods.
Maybe add some aero aids like they have for the eco ceed?
higher tyre pressure or low rolling resistent tyres?

I like to improve fuel economy of all my cars i have owned one of the best
was an 1957 morris minor that got down to 5l/100km at 110km/h and was about
10 seconds faster to 100km/h then standed :banana:

Thumper,

Thanks for the explanation of how you went about it - makes sense now. I can see that you have been very thorough and logical in your approach. Would be great if the intercooler had variable louvers in front that were controlled by a temperature sensor.

The ECU must be mapped to increase the injection of fuel depending on the temperature of the air flowing out of the intercooler. Strange that fuel consumption can be increased by warming up an intercooler.

Bob