High mpg

Hi I'm new to this site and was hoping someone could help me. Just recently had a Puma 1.7 and it had a new lambda sensor when it was mot'd by the previous owner. Smells of fuel and sometimes hard to start just after stopping. So I put me code reader on and it said lambda P1131 so I changed it for another erased the code and all was fine.then a week later the same code! Very high mpg the whole time I have owned it.

the Puma is known for having a start-stop-start issue. Happened to me when I first got the car as I wasn't aware it is sometimes a pig to start if you do short trips. I just turned the ignition on and waited 3 - 4 seconds (time for the fuel pump to pressure up) and it then fired straight into life.

Never failed to start after short trips again in 4 years by doing this 'waiting game' everytime and I got used to it so no 'chore'. I do it in all cars now as a habit.

Should cure that problem....

As for fuel smell, that could be anything. Regarding above, I never once pressed the throttle on start up and never have on any car since fuel injection was the norm as that can cause starting problems and more importantly give you your fuel smell your getting. Then again it could be a fuel filter leak or any other fuel line leak.

My first point of call would be checking the fuel filter and changing if necessary....incredibly easy to get to and change and for some reason almost always neglected :roll:

Hi thanks will have a look at filter. Petrol smell not as bad since I changed lambda's but the mpg is ridiculous and as I said the code is back for faulty lambda, is there anything that can cause lambda's to keep failing? Thanks for the replys.

What year Puma do you have as later ones have 2 Lambda sensors

strange, i would have thought a dodgy lambda would have reduced MPG as it wont be giving correct feedback for fueling not made it better!

Regards to fuel smell look at your two fuel line and check for damage or dodgy connection. If no luck try starting the car and check around again for obvious fuel leaks.

No sign of leaks. Will disconnect lambda and see if that helps.

It's a t reg 1999 only one lambda.

Would also check the fuel tank for signs of leaking around the seam also a common fail

Or also worth having a look at are the seals arounf fuel injectors

Thanks guys but got no leaks anywhere, It's not just me going from the wifes diesel mondeo back to petrol again? (Last car mondy mk2 2.0 petrol) I'm sure that I got 70 -80 miles to £10. Puma 45 miles to £10 thats driving like miss daisy!

Sometimes that's all I would've got out of mine, but other times it was more.

The fuel gauges aren't the most reliable/accurate things in the world.... you could drive your car and have half a tank when you park it up and turn it off, just to find you've only really got just over quarter of a tank when you next start it up!

Had lots of fords over the years I know fuel gauges aren't the most reliable of things but the 2 fiesta's me and the wife (mark4 1.3 & mark5 1.25) owned didn't seem this inaccurate if thats what it is. Ok I know a 1.7 is a bit different in engine size but if anything it should better power to weight ratio. As in 5th gear from 30mph onwards. Thanks for all the help so far guys.

fordmondyman said:

Very high mpg the whole time I have owned it.

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Just to be clear on this, do you mean that you are getting more than, say, 50mpg, or do you mean the fuel consumption is high, say, 25mpg?

I am swinging all the time in region of 42-48 mpg… If that helps you

hi PaulQ was only getting 45 miles to £10 of fuel (£1.28 L ) but have unplugged lambda and put Vpower ( £1.48 L ) in her getting more like 65 - 70 miles from £10 now

You were getting 26mpg, you are now getting 45mpg. If you are getting 45mpg, this indicates that you are not heavy-footed.

Just recently had a Puma 1.7 and it had a new lambda sensor when it was mot'd

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I reckon that the lambda sensor was duff, i.e. sending wrong information - it's not unknown.

Pragmatically, if the engine is behaving itself, you seem to have cured the problem. If you have a friendly garage, you might like to have the exhaust gases analysed* to ensure that they are within legal limits. I say this not because your Puma alone is responsible for all Global Warming and kittens dying, but, come the MOT time, it could be a failure.

* shouldn't cost more than £10.

No no no no.

Lean condition on the lambda sensor indicates the mixture can't be corrected.

Lean mixture is either not enough fuel or too much air. Both of which the ECU will attempt to correct.

As you can smell fuel and its using a lot, I'd go with the latter.

Sounds very much to me like un-metered air on the intake somewhere so the fuel is being massively overcompensated.

To diagnose properly(!) and not just blame the sensor, check the spark plugs for fouling and the intake for leaks (spray brake cleaner or similar around gaskets and joints - if it revs up, the leak is sucking in the flammable substance).

On the 1.7s pay particular attention to the PCV pipes (97MF-6C342-AA) under the upper inlet. This pic is a bit misleading as the two upper bits run parallel to the cams but this is the pipe in question - http://fordcat.ru/shop/1/parts/1206596" onclick="window.open(this.href);return false;

May also indicate MAF although that would give you different codes and normally a poor idle.