Hi there,
I’ve got a 1990 Eunos Roadster 1.6 that up until recently has been running perfectly well but over the past month I’ve noticed the fuel consumption has increased. At the moment it’s doing about 195 miles to the tank with an MPG of around 25. This is mostly stop/start driving to and from work. Driving to my parents house in York I used to use just over half a tank, I did it at the weekend and it used over 3/4.
I recently got the car serviced and mentioned that it had been running with a low MPG but they said that the emissions were very good for such an old car. Halfords across the road do a fuel service for £35-70 but I don’t want to take it if they’re just going to tell me the same thing.
Having looked already on forums I’ve noticed people talking about recalibrating the ECU? Does anyone know anywhere in Manchester that might do this? I noticed the change after I filled the tank with Premium unleaded which I’ve never done before (or since) so I don’t know whether this had an effect.
Apologies for my distinct lack of knowledge on all things mechanical but was hoping someone might be able to help?
Many thanks,
Polly
Hi Polly, try some Redex fuel injector cleaner (currently £2 a throw in Asda!!!) it says to use half the bottle per tankful but put the whole lot in and see the improvement it brings 
The other thing to check is your oxygen sensor, the on board diagnostics will signal if this is at fault but you will need to find somene local to you to check it for fault codes. A mis-behaving O2 sensor will definately cause higher fuel consumption, when they pack up the inside of your exhaust pipe and possibly the bumper near it will be much sootier than usual as an initial check.
They are not too expensive but if you get one make sure it has a plug on it and not a bare wired one as they cannot be soldered and as they only carry a millivolt signal any kind of joining up will impair the reading.
Hope this helps?
Dr. Eunos
So the garage actually measured the emissions and said they were OK? Did they give you a printout with the figures? (I’m sure Halfords would just tell you the same thing.)
Common reasons for increased fuel consumption are a faulty lambda sensor or engine temperature sensor, but either of those would make the emissions look rich. If it’s not rich, then it must be something else. Maybe an accumulation of little things. Low tyre pressure can lose you 1 or 2 mpg for example.
Can I also suggest you collect accurate miles/litres figures for a couple of tankfuls just to make sure there is a real problem.
I’ve measured the mileage for about 4 tankfuls now and it’s reading the same each time. I rang the garage that carried out my service the other day to see if there was anything else they could do to help but they reiterated the fact that the emissions were very good (no printout though) and that i’d probably need to take it somewhere to get it retuned or something. I just don’t know where to take it!
I’ll pump the tyres up again tonight and see if that has any effect.
Thank you for your responses.
Polly
Since your car is a 1990 one, it would be worth checking for any wobble on the crank pulley when the engine’s idling.
That’s a particular issue for cars up to mid-1991 due to the original crank nose design tending to let the timing pulley work loose if it’s not torqued up just right. I think owners usually report loss of power, particularly at low revs, rather than poor fuel economy, but it wouldn’t hurt to look. If it’s caught early, the wear to the crank nose can be repaired.