1.5 diesel poor fuel consumption

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1.5 diesel poor fuel consumption

Post by rayyzfr1 » 16 May 2018, 18:17

Hi everyone. Ive recently got a 1.5 diesel as an every day run about. I am confused and stumped as to its fuel consumption. I only get around 30-35mpg from it. Its only done 49000 miles, has just had a full service including cambelt etc and starts and runs perfect. No smoke, starts first time every time and pulls very well. I personally drive very carefully, in fact sometimes maybe to careful, i dont thrash it and accelerate gently.
Has anyone ever had poir mog from a diesel 106
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Re: 1.5 diesel poor fuel consumption

Post by JohnD » 16 May 2018, 20:51

It should be doing much better than that. Mine is just used as a run-about but gives me around 48mpg. Has the fuel consumption changed since the cambelt was done? Is the air filter clean and the pipe work clear?
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Re: 1.5 diesel poor fuel consumption

Post by Michel » 16 May 2018, 23:03

Check air filter and fuel filter, and thrash the living daylights out of it for a week. I guarantee it will be so much better, far more economical and nicer to drive after that.
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Re: 1.5 diesel poor fuel consumpti

Post by white exec » 17 May 2018, 06:48

And a 200:1 (remedial) dose of Miller's Diesel Power Plus, or Wynn's Diesel Fuel Treatment, in the tank.
Also avoid supermarket fuel, and go for something better (eg Esso), but no need to buy the expensive version.
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Re: 1.5 diesel poor fuel consumpti

Post by Bick » 17 May 2018, 08:08

white exec wrote:
17 May 2018, 06:48
And a 200:1 (remedial) dose of Miller's Diesel Power Plus, or Wynn's Diesel Fuel Treatment, in the tank.
Also avoid supermarket fuel, and go for something better (eg Esso), but no need to buy the expensive version.


Hi Mr exec - have you noticed a difference in supermarket fuel? I ask because i havent, yet i still dont like using it but when i do mileage is okay!

Sorry if this is classed as a thread hijack mr admin
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Re: 1.5 diesel poor fuel consumpti

Post by Michel » 17 May 2018, 08:16

Bick wrote:
17 May 2018, 08:08
white exec wrote:
17 May 2018, 06:48
And a 200:1 (remedial) dose of Miller's Diesel Power Plus, or Wynn's Diesel Fuel Treatment, in the tank.
Also avoid supermarket fuel, and go for something better (eg Esso), but no need to buy the expensive version.


Hi Mr exec - have you noticed a difference in supermarket fuel? I ask because i havent, yet i still dont like using it but when i do mileage is okay!

Sorry if this is classed as a thread hijack mr admin


Personally, no, I have not noticed a difference. Others say they have. I tend to put fuel in when and where I need it.

I get more mpg out of supermarket (Sainsbury) bog-standard 95 RON unleaded on my motorbike than I do on Shell V-power, that I know for a fact.
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Re: 1.5 diesel poor fuel consumption

Post by white exec » 17 May 2018, 08:44

My own experience is little difference between supermarket/budget fuel and leading brand when it comes to petrol.

On diesel, quite another matter...
Some drivers/engines will notice the difference, others don't.
Price difference between the two sources is partly explained by the reduced amount of additives (not cheap) added to the diesel fuel when tankers are filled.
For diesel, these additives improve the combustion of the fuel, as well adding lubrication and cleaning agents, important for pumps and injectors.
With these additives present, many engines will provide quieter running, better fuel consumption, and better pulling power (more torque) at low engine revs., while also keeping fuel systems clean, fewer deposits in the exhaust, and less smoke.

Many diesel specialist workshops advise against running diesel cars on a constant diet of supermarket/budget fuel, and recommend:
- at least periodic use of a good quality fuel
- in the case of smoke or indifferent running, use of a fuel cleaner (eg Miller's or Wynn's)
- a regular stint of high-speed driving ('Italian tune-up')
Lack of all these things risks MoT/testing failure on emissions.

Not everyone notices the difference in running good fuel and periodic additive.
We have, on several Citroen diesels, and even more so on our Toyota D4D.

The additives present in better quality fuel are also present in the Miller's and Wynn's products.
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Re: 1.5 diesel poor fuel consumption

Post by xantia_v6 » 17 May 2018, 08:50

Do you know if the consumption was better before the timing belt change? Maybe the timing is retarded?
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Re: 1.5 diesel poor fuel consumption

Post by Michel » 17 May 2018, 10:11

white exec wrote:
17 May 2018, 08:44

- a regular stint of high-speed driving ('Italian tune-up')


I firmly believe this is the most important part of owning a diesel car. I've had many over the years, and nearly all of them have been sluggish and slow (Kev's RUNN Xantia TD was a notable exception) when I bought them. The worst was a Xantia TD Estate I bought with 75k on it. It struggled to do 85mph when I got it. I drove it hard for a month, and the economy improved greatly, and it became capable of cruising at 3-figure speeds where permitted. I think it's unsurprising that many diesel cars are like this when bought s/h, as people buy them for economy and drive them gently. I think this has a more detrimental effect than supermarket fuel, or not using additives.
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Re: 1.5 diesel poor fuel consumption

Post by rayyzfr1 » 17 May 2018, 17:23

xantia_v6 wrote:
17 May 2018, 08:50
Do you know if the consumption was better before the timing belt change? Maybe the timing is retarded?

Hi. No it was terrible when I first got it, that was one reason I had a full service, oil, filter, air filter, cambelt, water pump and aux belt. It’s had some injector cleaner in the tank. Car runs, pulls extremely well with no smoke and starts first time hot or cold, engine is very quiet ( for an old diesel). Only thing I could think of was the pump itself even though it’s only done 49,000 miles. Just been mot’d and passed emissions with ease
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Re: 1.5 diesel poor fuel consumption

Post by JohnD » 17 May 2018, 21:11

rayyzfr1 wrote:
17 May 2018, 17:23
engine is very quiet


My Saxo is also low mileage but it's anything but quiet. When it starts up it's embarrassingly agricultural. I would remove the top front cover, slip a 6mm rod into the flywheel and check the holes in the cam and pump pulleys. Timing could be slightly out.
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Re: 1.5 diesel poor fuel consumption

Post by rayyzfr1 » 17 May 2018, 21:20

JohnD wrote:
17 May 2018, 21:11
rayyzfr1 wrote:
17 May 2018, 17:23
engine is very quiet


My Saxo is also low mileage but it's anything but quiet. When it starts up it's embarrassingly agricultural. I would remove the top front cover, slip a 6mm rod into the flywheel and check the holes in the cam and pump pulleys. Timing could be slightly out.

Timing has been checked. It’s bang on. All 3 pins and bolt line up perfectly. The only thing that hasn’t been altered is the variable timing on the cam and diesel pump. They stayed locked in the same place
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Re: 1.5 diesel poor fuel consumption

Post by JohnD » 17 May 2018, 21:28

When the belt was fitted and the timing pins put in, the three bolts holding each pulley on to it's hub should have been loose with the bolts at the centre of the slots. Only after the belt was tensioned should the bolts be tightened.
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Re: 1.5 diesel poor fuel consumption

Post by rayyzfr1 » 17 May 2018, 21:52

When the belt is tensioned after tightening it where should the 3 bolts on the pulleys be exactly before their tightened up
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Re: 1.5 diesel poor fuel consumption

Post by JohnD » 18 May 2018, 09:31

rayyzfr1 wrote:
17 May 2018, 21:52
When the belt is tensioned after tightening it where should the 3 bolts on the pulleys be exactly before their tightened up


Before the belt is put on, with the engine timing aligned at the flywheel, the cam shaft and the fuel pump, the three bolts in the two sprockets should just be finger tight. Then they should be turned fully clockwise to the ends of their slots. The belt should now be fitted starting at the crank pulley. Next around the idler pulley and on to the fuel pump, turning the sprocket anti-clockwise to enable the belt to seat properly. Making sure the belt remains taught, fit it to the cam sprocket in the same way. Put the belt round the tensioner pulley then the water pump. With the six sprocket bolts still only finger tight, tension the belt to the required figure. When it's correct, check that the six bolts are not touching the ends of the slots, and tighten them. According to Citroen's instructions the timing tools should be removed, the engine turned ten times by hand, then the timing pins replaced, the tensioner pulley loosened, the six bolts loosened and the tensioning re-done.
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