Poor mpg k11 cvt....................!!!

[K11cvt]

hi everyone,

my car is a 2001 K11 1.0L auto (cvt) with 60,000 on the clock.

Its the face-lift Bosch coil pack and throttle body version

Did a test today and came up with an average MPG of just 35.4 (this is a mixture of town and motorway driving) the book says I should be getting a COMBINED figure of 46.5 even with a CVT auto box.

She's had a full service (correct Bosch spark plugs,oil + filter, air filter, fuel filter, coolant and gearbox oil change) now I'm thinking that the problem might be with the removable MAF sensor as she seerms down on power until the engine warms up to operating temp and at idle/tick over there is more noise than I would like and a slight judder that can be felt through the steering wheel.

On the move everything is ok....no hesitation or stalling problems....just bad MPG. I've cleaned the throttle body and sensor by spraying cab cleaner at it but that hasn't helped.

The engine management light did come on a while back but turned itself off after she was serviced!!!!! At the moment no EM light is showing. I've seen some MAF's on ebay, they're not the original Bosch but an aftermarket part......?

Any ideas would be very welcome.


Thank you

 

[wizardwind]

When you say down on power,what do you mean?.Does it hesitate under throttle or over rev and go nowhere....

 

[K11cvt]

down on power....no not hesitant or over rev - its a bit like driving with the handbrake slightly on. Once its up to temp its ok. Was hoping to get at least 45 mpg from a 1.0L

 

[peposhi]

Well... You can be happy you haven't got my k11 '99 Auto with fuel consumption - 29-30mpg :wow:

Could be wide tyres, O2 sensor, catalyst... I'm thinking to drill my cat and make it free flow, to let my car breathe

 

[Dave_Ally]

Depends how harsh you're driving it in fairness, motorway speeds will start to drink and drink fuel. You should really get your front lambda checked that voltage is OK and switching in good time, eBay MAFs are OK but not as good as the real deal (mine was swapped 3 times in total!). Juddering idle on mine was caused by an air leak in the throttle body/vacuum pipes but mine was to the point where the steering wheel was vibrating harshly and revs were down to 550-640.

Also check basics, tyre pressure etc.? I've been getting about 35MPG on my 1.4 manual with similar mixed amounts of driving despite all my issues recently and long term fuel trim hanging around 20-23% so I'm hoping to see an increase in MPG when it drops down again. If you've had an EML code come up just before it was serviced it will still be in the history probably if you get the ECU read.

 

[K11cvt]

thanks for the advice.....I drive normally, not a boy racer, standard tyres fitted with correct pressure, will check for leaks as you mentioned......I don't have an engine management light on so the lambar and maf should be functioning correctly shouldn't they? I'm bloody annoyed......my previous K11's were all pre-coil pack versions and didn't give me any problems at all!

 

[Dave_Ally]

Not necessarily, my EML light was on and off for months before I eventually seem to have got mine sorted out. In my case my fuel trim was just 2% below 25% which would have thrown the light back on again for running lean bank 1. If your MAF is bad it will be under reading to the O2 sensor which will be making it run rich depending on how bad your issue is. My previous was a 1.3 without the coil packs and it gave me no real trouble either, I still like this one just as much though.

 

[K11cvt]

thanks for that......so looks like possible causes are
1) maf
2) lambar (which one though)
3) coolant temp sensor

will have to work through a process of elimination......I'll get there eventually

thanks again will keep you posted

 

[Dave_Ally]

More than likely it will be the front lambda if one of them is bad, you could check the post-cat lambda also if you like but I think that one is mainly for emissions purposes. But check the basics first before you spend hard earned money
If you are changing the lambda, try and get a genuine Bosch one - turned out mine despised a universal one. :laugh:

 

[K11cvt]

will do thanks. I haven't changed a coolant sensor or a lambar before.....the lambar looks like it just screws in like a spark plug but has three wires coming out of it.....I'm guessing these have to be cut and rewired? same as the coolant sensor?

 

[wizardwind]

As questios are being fired.
What affect does a faulty temp sensor have? and would the gauge going up to normal running temperature within 5 minutes indicate a fault,or is this common?

 

[wizardwind]

will do thanks. I haven't changed a coolant sensor or a lambar before.....the lambar looks like it just screws in like a spark plug but has three wires coming out of it.....I'm guessing these have to be cut and rewired? same as the coolant sensor?

Don't cut,just unplug at junction and unscrew sensor.

 

[K11cvt]

thanks for that will have a look tomorrow when its light