Low MPG...what could be wrong?

[EvilDonut]

I recently tried measuring my MPG and it is consistently coming out at about 30 - actually about 29.5ish. This is way below what the puma should do and I'm wondering what the problem could be.

I have a superchips bluefin ECU remap that will probably affect things, but I'd be surprised if it was reducing efficiency that much.

What kind of problems could be causing this low mpg? Are there any test I could do to help track down the problem? I guess the main thing I should try is remap the ECU back to normal and then fill up a tank and retest the MPG. Anything else?

Its not burning through oil at an unreasonable rate - the level may drop from the 'max' line to the 'min' line in about 2 months maybe.

 

[hotrodspike]

If you've got a digital dash check the fault codes, if it says 131 ish then your O2 sensor(s) are up the chuff. If they are don't buy the "universal" ones off ebay, they're crap. Look on ebay for a place called Transitparts UK, they do genuine Ford ones for £30

 

[crystalpuma]

30 is easily achieveable if you aren't driving especially for good mpg. Kev used to get about 25mpg from his and there was nothing wrong with it.

 

[EvilDonut]

I've not got any fault codes nope

I've tried driving for good mpg and I get a max of 250 miles to a full tank - that works out at 28.4mpg, which is actually a bit under what I said before but I worked it out again with a proper calculator and thats what I get :/

Surely that means theres something wrong with mine when other people are getting near 40mpg on their 1.7 pumas?

 

[yippeekiay]

I'd say so but it depends what 'your' driving for good mpg means.

The best way to get high mpg without too slow a progress is by doing a good long run at an indicated 60mph on a dual carraigeway/motorway. When I did my economy run I did it at 50mph but recently I got nearly the same (if not more if I'd carried on until I ran out) by doing 60mph.

Also, the only ways to really check mpg is to either;-
1) Run the car until empty and put an exact amount of fuel back in then drive until you run out OR..and the next way is my prefered method for the obvious reasons of not getting crap from the bottom of your tank getting sucked in etc...
2) Fill the car to the brim...and I mean to the BRIM!!...not until it clicks, until you can get no more in there even after waiting for the air bubbles to come and go. Then go for a drive of however long you want - I'd say drive for an hour away from the garage (or half an hour at least) and then return to the garage you filled up at and refill to the BRIM. Then work out your mpg.

At a constant 60mph you should get over 50mpg. If your not anywhere near then something could be amiss. If you are getting around 50mpg then your normal driving style or the routes you drive daily are the problem.

 

[EvilDonut]

Hmm ok sounds like a good test to try, I can do a lap or two of the M60 at 60mph and see what I get.

When I calculated my mpg at 30, I would have been doing mostly commuting - i.e. stop/start at slow speeds, mixed in with some motorway driving. So thats not ideal for mpg I guess.

I think the O2 sensor is fine because I've been reading the air/fuel percentage calculated by the ECU and it seems to vary normally (stay around 0% and sometimes go up to about 5% rich, but virtually never go lean)