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Discussion Starter · #1 ·
Hi

My Zafira 1.9 TDi 150 (08 Reg) with 35,000 miles on the clock struggles to do 36 MPG in urban driving and we once got 41MPG on a 200 mile motorway trip in the middle of the night, hardly any traffic, nearly all the way on cruise control at 75 MPH. Is this as good as it gets? Our old 'A' series did much better than this, in fact a much better car all round. I've had the car back to the dealers several times but they say there are no faults.

Recently I had our second car, not a Vauxhall, taken to a specialist garage to have the Body Control Unit sorted, after all the electrics failed. It had suffered a total loss of memory so needed reprogramming and they were the only people in the area who could do it. I noticed lots of Vauxhalls in his carpark and asked if he was a Vauxhall dealer he said no but the local dealers sent all makes of cars to him to sort out electronic faults. He resurrected the BCU on our other car when the main agent had said it needed a new unit saving me £400.

Having read about after market chips to improve both performance and fuel economy I asked him if he could do anything about the fuel consumption on my Zafira. Having checked which model it was he suggested that it needed the EGR valve changing and the software updating and that should improve the fuel economy.

However I see from comments on here that lots of people are blanking off this valve and getting better running and economy. I was told by my Vauxhall dealer that the system was used to burn off carbon in the particulate filter using fuel from the car and if the filter blocked, the engine will fill up with diesel and blow up. Futhermore I was warned that it would not pass an MOT if the system was tampered with. The car is due it's first MOT in June so I wouldn't want it to fail on this.

The car does a fair bit of motorway work so it should be burning off the carbon but again I read on here that the cleaning cycle is not initiated by whether the system needs cleaning but some other factor. Can someone sort out the real truth from all this. With fuel going up like this it seems crazy waste it if consumption can be reduced and yes I do on occasions put my foot down, but why have 150 horses and not enjoy them now and again.

Cheers

John
 

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Discussion Starter · #2 ·
Experts

Hi

Are there no experts out there who can advise me about the issues involved in improving the fuel economy on my Zafira?
 

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Hi - I can't offer any expertise on improving your economy , but as I also have an 08 Zafira 1.9 TDI 150 (with approx 32k miles on it) I thought I could at least give you a comparison !

Urban economy is usually around early 30's MPG , worse if a DPF regeneration occurs.

A longer run with mixed driving will usually get economy up to around 40 MPG , and a mainly motorway journey around 45MPG.

Last summer I did a round trip of around 2000 miles to France , with 4 people and a boot (very) full of luggage and over the whole trip managed 46MPG.

With regard to the DPF 'cleaning' my understanding is that once a threshold is reached - x% full - then the cleaning is initiated , but only once the engine gets to a certain speed / revs. I must say I had concerns about the DPF before I got the car , but so far it seems to clean approx every 300-400 miles with no issue , just hammers the fuel consumption when it is doing it.

Hope that's some help.
 

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I have an `07reg 1.6 petrol and achieve similar urban and motorway mpg figures so am well impressed :) Petrol engine technology seems to have improved such a lot in recent years. Before the Zaf I had a 2.4 petrol Previa and most people I knew with the 2.2 diesel import Estimas could not match my mpg figures??
 

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Discussion Starter · #5 ·
Thanks to both of you for the input. It really does concern me that diesel is being pumped into the exhaust at uncertain intervals to burn off carbon particles that may not even be there. Does anyone out there really know how it all works and to what purpose. How many other makes of diesel cars use the same system.

I've been driving diesels since 1970 most years doing around 100,000 a year. Diesel engines then were quite slow reving but very rugged and you got 4 times the mileage out of them compared to a petrol one and less frequent servicing, and of course diesel was so much cheaper than petrol. I have heard that diesels are out of favour because the small particles of soot in the exhaust gas was found to be bad for everyones lungs, hence I presume the filter in the exhaust and presumably led to the government policy? to price diesel cars off the road.

I think Rob is right about petrol cars. Gone are the day of services every 3000 miles and new plugs every 10,000. I have a small sports car with a highly tuned non turbo petrol engine and it does much better MPG that my Zafira. Mind you my Zafira hasn't locked me out of the car and shut off all the electronics because it thinks I'm trying to steal it! Not yet anyway but that's another story.
 
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