Mk1 Eunos 25MPG normal?

[trevkx125]

Hi,

Our Mk1 Eunos Roadster only manages 180 miles per tank (40+litres to fill back up). It is an auto, but surely is should do more than that? I recently serviced it, new plugs/air filter/belts etc etc, didn't make any difference. Mainly used for a 13 mile commute which 50% of the road is national speed limit. Driven slowly most of the time too, not nailed everywhere!

The only problem I can find is the idle speed can is a bit erratic, its slightly high when warm, idling at 1000-1200RPM but from cold idles smoothly at 850/900rpm on the tacho?

Can you recommend anything to check? Maybe Lambda sensor/air flow meter....etc..???(Its just passed its MOT, emissions apparently ok, but the guy mentioned the high idle speed)

Sorry for the hugely boring post, but its getting too fecking expensive to run!
Many thanks!!

Trev

[Munter]

25 is only a little on the low side for a manual. So I can believe an auto would get 25.

[Dan_1981]

My manual mk1 1.8 get around28mpg.

Yours sounds about right for an auto.

[anonymous-user]

I used to get 40mpg from my previous 1.6 mk1 Eunos, when it was being driven about 12 miles a day on A-roads and through reasonable amounts of traffic to work and back.

No idea about the current one, it just gets thrashed.

[trevkx125]

Cheers for the replies!! Looks like its normalish then.............bugger!

[MX-5 Lazza]

It can probably be improved... hit & miss though. Try changing the temp sensors on the back of the block (green - difficult to get to) and on top of the thermostat first. Changing the O2 sensor might also have an affect but they aren't cheap unless you can find a known good one 2nd hand. Of course you might change those and still have the same mpg...

[NiceCupOfTea]

MX-5 Lazza said:

It can probably be improved... hit & miss though. Try changing the temp sensors on the back of the block (green - difficult to get to) and on top of the thermostat first. Changing the O2 sensor might also have an affect but they aren't cheap unless you can find a known good one 2nd hand. Of course you might change those and still have the same mpg...

Isn't the stat sensor a sender for the guage (and I think it's 1.6 only) - don't remember anything around there when I did my 1.8's thermostat.

Sadly 25mpg is normal - I get between 23-25 on average but most of my stuff is either around town or thrashing so not terribly efficient.

Look at it the same way I do - when you upgrade to a V8 the fuel consumption won't be a consideration!

[Slinky]

I seem to recall that Jap stuff typically runs relatively rich, hence the lower than average MPG returns..

[franv8]

I'm not sure that the front (stat) sensor is actually the fan activation switch?

There's two senders in the back of the head. One in the blanking plate (which I think may be the ECU temp sensor) and a small brass one in a horizontal drilling into the cast flange on same piece of the back of the head, I think this is the temperature gauge one.

I could be completely wrong...

My manual does around 27mpg (Mk1 Eunos) whether it's being thrashed or driven normally. Extremely gentle driving gets it to 30-32 mpg. I'm always a bit dissapointed as to how much gas the little 1.6 uses, other than that it's brilliant.

[MX-5 Lazza]

I was assuming it was a 1.6. I only say replace both because they are quite cheap and you might as well do both at the same time.
Getting the AFM adjusted can stop it running rich too if you can find someone who knows how to do that. 40mpg should be possible from a perfectly running 1.6.