Ok. so constant advice given is that a tune up will increase fuel economy. i suppose back in the day this would have been true with tune ups involving carb balancing, de-coking, mechanical fuel pump adjustments etc. But on a modern car, how is the difference (if there is one) achieved! My car drinks like a fish. And people keep on telling me to give it a tune-up and that should sort it. I wont tell you what it is, so that there are no comments about me buying a guzzler. But it is a mid 90's model EFI. So, realistically, how do the different parts of a modern engine tune up (oil change, spark plug change, filter change etc.) affect fuel economy!
morrisman1,
Nov 1, 12:18am
Whats the big secret about the car model! Nobody can offer any quality advice without knowing it because different engines have different weak points which can affect economy.
I suggest you let us know the make/model/engine code and transmission otherwise you won't get much out of this
zx2r,
Nov 1, 12:56am
perhaps i will. i guess my initial question was a very general one - i.e. how does changing oil affect fuel economy! or how does doing valve clearances affect fuel economy! I have a ST195 caldina with a 3s-fe, and a 4wd auto box. from a 50L fill i get ~370k round town and ~600k long distance.
pollymay,
Nov 1, 1:01am
Oil of different viscosity will change economy, less friction is less more economy and also there is more than fuel economy, vehicle repairs also factor into the cost of running a car, the type of tyres changes how much it is to run as does the wear pattern of the pressures you run, if they are high and wear out the middle that's pretty useless isn't it.
Filters are obvious, if it's working to draw air it's working harder to move, if the fuel filter is clogged then it will compensate with the injector cycle using the O2 readings and may cycle up and down more. Spark plugs mean a more complete burn and your O2 will pick that up under light cruising and should use less fuel.
There are plenty of gains and little reason to treat your car like crap when half of it is so easy.
morrisman1,
Nov 1, 1:07am
I wouldnt call that economy too shabby. Considering it is a medium size car with automatic and 4wd the open road figure is about what you would expect. Around town will always be more.
Changing oil technically shouldnt change economy unless it is significantly overdue and the oil is a stickly gunky mess and in that case the new oil will give less friction and thus better economy.
Valve clearances certainly can affect economy because it can stuff up the timing of the valves so they may open too late then shut too quick and there are various techniques used to optimise flows (which I dont understand properly, an engine builder should be able to help there) which may not work as designed and subsequently affect economy.
musikcrazee,
Nov 1, 1:14am
had my 93 corona 2WD auto with the 3s-fe for 5 years now. 260,000km and I average about 700km open road driving and no more than 500km city driving to a tank. The 3sfe drinks if you are doing a lot of around town driving. I run 20w-50 oil in the summer when doing heaps of road trips. Has semi synthetic 15w40 in it at the moment and haven't seen that bigger difference in fuel economy.
mike77,
Nov 1, 7:20am
I reckon,
And thanks for making me feel better about how much gas I use!
pollymay,
Nov 1, 7:41am
Oh and I'll add valve timing and all that is to do with efficiency and compressor loses (an engine is a big compressor). Incorrect valve timing means your car in simple terms is not making the power it should at the revs it is cruising at, more throttle to maintain speed = more fuel. Valve clearance changes valve timing, as an engine wears the valve can sit into the seat further, this causes the clearances to close up and you can burn an exhaust valve if clearance gets low enough which will require engine teardown. A 3sfe has great valves and seats though, go forever usually, the valve stem seals die early though which causes smoke on startup, keep the oil topped up and it's no big deal.
Valve clearances are probably not going to make an appreciable economy difference, burning a valve will hit you in the pocket though.
grangies,
Nov 1, 8:16am
We can stretch out our old Mercedes 380se to 700km per 75 litres . ( 10.7 per 100km )
We do no city driving. When we did, we'd get about 12.5l per 100km.
We never drive it hard . But for a 30 year oldV8 ( only 3.8 litre V8 though ) . I reckon it's pretty good.
The vehicle is about 1700kg and longer than a VX body Toyota Landcruiser.
If we drove it like a maniac though, I reckon we could double the fuel use.
phillip.weston,
Nov 2, 12:33am
I have an SV21 Camry here in 'Straya with the 3S-FE and auto-magic box. Just ticked over 333,333kms. I can easily obtain 6.5-7L/100km on long open road trips and the worst I can do with 100% city driving is 9.5-10L/100km with air conditioning on.
I would say most of your fuel consumption would come from the extra weight and drive-train sap of the 4WD system.
What I would do to try help with fuel economy:
* go to a servo and check tyre pressures, pump them up to 36-38psi if regular 60-70 profile tyres, 40-45psi if lower profile tyres * clean out the car of any un-necessary junk, including what's in the boot that you don't need to cart around at all times * if it has a roof rack and you're not using it - remove it! * a 'service' on that car would consist of new spark plugs with the gaps set to 0.8mm, a new air filter, an oil & filter change with 10W30 oil and perhaps even a fuel filter change too. * get a wheel alignment done if one hasn't been carried out in the last 12 months * run it on 95 octane instead of 91 octane, probably wont notice results until at least 2-3 tanks later.
vtecintegra,
Nov 2, 12:40am
The combination of 4wd and a primitive auto gearbox does murder urban fuel economy, especially if hills are involved.
That said your urban economy is about 1.5l/100km worse than I was getting in an auto 4wd turbo Avenir in Wellington so there is a bit of room for improvement there. On my car I found I got better economy at low speeds by switching O/D off on the transmission, you may want to experiment with that.
pollymay,
Nov 2, 5:04am
turbos are actually more efficient if driven right
morrisman1,
Nov 2, 5:11am
perhaps they have a better specific fuel consumption but also the ECU tune will have a big impact on the economy as some will run super rich to avoid detonation
moosie_21,
Nov 2, 5:37am
Have a 3sfe '93 Celica. Did wonders when I had it tuned up (new spark plugs, hi-performance oil filter, 10W-30 oil, K&N filter, new fuel filter and de-carbon, running it on 95, new tyres) from previous owner. Usually get 700-750 km's a tank on long hauls. Have learnt to use less pedal to the floor driving to and from work everyday, and that certainly helps, but as above, the autobox just murders economy in it. Hopefully getting a 3sge Beams tranplant soon with manual gearbox, way better economy!
vtecintegra,
Jan 24, 1:48am
In some cases. I really don't think the SR20DET is one of them
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