Poor fuel economy from an MG ZR 120+

ajgoodfellow

ajgoodfellow

ajgoodfellow

Soldato
Joined
24 Dec 2004
Posts
11,373
Location
Knowle, Solihull, UK
Hi

Just bought my ZR back in March and I'm really happy with it. Recently though, the fuel economy has been getting worse and worse

When I first bought the car I was averaging about 35-36mpg on Super Unleaded. This was a mix of driving, a fair bit involved blasting the car around back roads in a low gear doing no favours for the consumption!

Over the last few months though it has been dropping and I now average about 24mpg. This has been on my daily commute to work and back - 25 miles each way of which about 20 miles is on a dual carriageway. This average has been the same for the last few tanks

I've tried different fuels but it hasn't really helped. I've currently got Shell V-Power in the tank and it looks like it'll average about the same as the previous tanks on Total Super and Sainsbury's Super Unleaded.

Apart from the economy the car is running fine - it'll always start first time (and quickly), it sounds good and it goes well. It doesn't seem to be as quick as when I first got it but I came from a 1.4 Astra so I've probably got used to the performance (and the heavy sub in the back can't help!)

A few months ago (4th October) the car had it's full 60k service (its on 45k at the moment but four years old) at a Rover dealer (well, Land Rover now!). They replaced the oil, coolant, oil and fuel filters, spark plugs, brank fluid, all of the brake pads, the front brake discs, washer fluid, etc. It's also had a brand new exhaust fitted (mid and rear sections) recently. The service, exhaust and MOT came to nearly £1000!

The car has good tyres with plenty of grip (matched Toyo Proxes on the front and matched Michelin Pilot Sports on the back) which are at the correct pressure. I check the various fluids every week and they're OK and I'm always carefull to to let the car warm up fully before I rev it above 3000rpm and I let it cool down before switching it off.



Thanking you in advance for your suggestions,



Alistair
 
was it a genuine exhaust or a cheap nasty pattern thing,


could explain a bit of your mpg loss and power drop.
 
silversurfer said:
Just unplug the battery for 5 mins should be enough. Make sure you have the pin to the car radio and alarm settings if needed.
Click to expand...

I know this won't work on a BMW, and, iirc, a few other cars, you have to short the battery cables together to achieve the re-set.

Obviously, once they are disconnected from the battery!

Not sure if the same applys to a Rover.

As already said, I cannot see a simple ECU reset curing such a considerable drop in MPG.

Take it to a spanner monkey. ;)
 
Thanks for the reply

My housemate reckons that I might need a new MAF sensor - what do you think? They're pretty expensive though it seems (looks like it's about £150+fitting)

I thought that the service would fix it personally as it was a "major" service where they changed the spark plugs, oil, filters, etc
 
ajgoodfellow said:
Thanks for the reply

My housemate reckons that I might need a new MAF sensor - what do you think? They're pretty expensive though it seems (looks like it's about £150+fitting)

I thought that the service would fix it personally as it was a "major" service where they changed the spark plugs, oil, filters, etc
Click to expand...

With the greatest respect, don't ask your mate, or guys here, your not going to get any definitive answers (unless, extremely lucky!) either way.

I'd be back having words with the garage if I were you, at least he can look at the car and make an accurate diagnosis.
 
I'd suspect it's overfuelling, so probably some electronic sensor like the coolant temp, mass airflow or crank position. I'm not that familiar with the K-series so I'm quoting from my VW experiences.

My old Bora started munching fuel when the coolant temp sensor was faulty then a couple of yeats later the crank position sensor went. Coolant sensor caused it to chucking too much fuel in when it was part warm which knocked about 6mpg off the average.
 
Definitely try a new coolant temp sensor; they're about six quid and can cause this issue (car thinks it's cold all the time and overfuels to compensate).

I forget the number and any relevant details but I know a company called Best of British (Rover) stocks them. I was after one for my T-series but they only had K's in stock.
 
[TW]Fox said:
Nearly £1k for a routine service on a 1.6 litre MG ZR? Thats insane!
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It does sound very pricey for the work done but it wasn't just a service if you read the original post. 60k service may well include the cambelt as well.
 
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