Problem with fuel consumption

besar001 · Mar 8, 2014

Hi folks.. I have a problem with fuel consumtions i think...

, My Rangie is 2.5 DSE automatic, 2001.. In the city my display show me about 18L/100 km after i clean the MAF in the same traffic on the city the display show me about 14-15L/100 km.... Is a maf problem?? How can i test the maf??? THNX Folks...

Druim · Mar 8, 2014

besar001 said:
Hi folks.. I have a problem with fuel consumtions i think... , My Rangie is 2.5 DSE automatic, 2001.. In the city my display show me about 18L/100 km after i clean the MAF in the same traffic on the city the display show me about 14-15L/100 km.... Is a maf problem?? How can i test the maf??? THNX Folks...

So it use less after cleaning maf, you should be happy about that

Now introduce yourself:mad2::mad2::mad2:

Datatek · Mar 8, 2014

14 to 15 litres per 100Km is not that far off the mark in city trafic.

wammers · Mar 8, 2014

Datatek said:
14 to 15 litres per 100Km is not that far off the mark in city trafic.

Complaining about going from about 15 MPG to about 20 MPG is a new one on me.

Datatek · Mar 9, 2014

wammers said:
Complaining about going from about 15 MPG to about 20 MPG is a new one on me.

Funny how cleaning the MAF improved the fuel consumption

gfromleeds · Mar 9, 2014

wammers said:
Complaining about going from about 15 MPG to about 20 MPG is a new one on me.

Forgive me if im wrong but 20mpg in city traffic??
Thats pretty good! !!
Mine only gets 22mpg and that's with about 35% motorway driving

Maybe I need to clean my MAF

Or get to the grip off a 2+ tonne car will drink it like an alcoholic just back from a week lost in the sahara

wammers · Mar 9, 2014

Datatek said:
Funny how cleaning the MAF improved the fuel consumption

Nothing funny about it at all. If the MAF is reading wrong it can cause the ECM to misinterpret air conditions. And cause incorrect EGR operation.

besar001 · Mar 9, 2014

Thank you. But after some days my consumption turnied back to 18 to 20 l/100km. I think i need to replace the MAF.

Datatek · Mar 9, 2014

wammers said:
Nothing funny about it at all. If the MAF is reading wrong it can cause the ECM to misinterpret air conditions. And cause incorrect EGR operation.

Funny how it does the same even with the EGR blanked.

wammers · Mar 9, 2014

Datatek said:
Funny how it does the same even with the EGR blanked.

It is still upsetting the ECM, well at least that is what BMW think but what do they know.

Datatek · Mar 10, 2014

wammers said:
It is still upsetting the ECM, well at least that is what BMW think but what do they know.

An ECM (or EDC) is a logical computer device, they don't get upset. The MAF affects the fine fuelling trims as per RAVE, with duff MAF readings the EDC runs default maps and it uses more fuel or adjusts the fuelling to an incorrect air reading.

wammers · Mar 10, 2014

Datatek said:
An ECM (or EDC) is a logical computer device, they don't get upset. The MAF affects the fine fuelling trims as per RAVE, with duff MAF readings the EDC runs default maps and it uses more fuel or adjusts the fuelling to an incorrect air reading.

Nonsense. Minimum fuel on a diesel is the fuel needed to maintain a given RPM. The air drawn into the MAF is feedback for the EGR so the ECU knows the air/exhaust gas ratio to fine tune EGR operation as laid out in EC level 2 emissions legislation to reduce NOx production. To reduce NOx production the air not needed by the engine to produce the requested RPM is replaced by exhaust gas. Simple as that. End of story.

Datatek · Mar 10, 2014

wammers said:
Nonsense. Minimum fuel on a diesel is the fuel needed to maintain a given RPM. The air drawn into the MAF is feedback for the EGR so the ECU knows the air/exhaust gas ratio to fine tune EGR operation as laid out in EC level 2 emissions legislation to reduce NOx production. To reduce NOx production the air not needed by the engine to produce the requested RPM is replaced by exhaust gas. Simple as that. End of story.

So why does fuel consumption go up with no MAF (or a duff MAF) even wth no EGR?

wammers · Mar 10, 2014

Datatek said:
So why does fuel consumption go up with no MAF (or a duff MAF) even wth no EGR?

Think i have already answered that. Remember the confused ECM.

landygirl87 · Mar 10, 2014

I have a 2.5dt that does at best 22 mpg, I also have a 4.2 V8 HSE that only does 15 at the worst, but I did get it up to 33.3 mpg in it with a lot of concentration on my driving skills (the 2.5dt, from Warwick to Scotland, and still had the almost full tank that I set off with)

Datatek · Mar 11, 2014

wammers said:
Think i have already answered that. Remember the confused ECM.

Senile dementia then in an ECU

Anything to avoid the obvious I suppose.

wammers · Mar 11, 2014

Datatek said:
Senile dementia then in an ECU
Anything to avoid the obvious I suppose.

BMW seem to agree with me though maybe you should send them an Email putting them right. They may rewrite their technical literature to suit your new ideas.

Datatek · Mar 11, 2014

wammers said:
BMW seem to agree with me though maybe you should send them an Email putting them right. They may rewrite their technical literature to suit your new ideas.

LR saw fit to rewrite it in tha last version of RAVE, I wonder why they would have wasted money doing that?
You still haven't explained why, with the the EGR blocked, disconnecting the MAF affects fuel consumption, smoke and according to some performance, as according to you it only affects EGR operation. Strange

wammers · Mar 11, 2014

Datatek said:
LR saw fit to rewrite it in tha last version of RAVE, I wonder why they would have wasted money doing that?
You still haven't explained why, with the the EGR blocked, disconnecting the MAF affects fuel consumption, smoke and according to some performance, as according to you it only affects EGR operation. Strange

Keith you obviously do not know how a diesel engine functions. The MAF CANNOT control fuelling subject to airflow through it. Fuelling is dependent on engine RPM and load. If you reduce the fuelling for any given throttle demand the RPM will drop, if that throttle demand is maintained fuelling will automatically be increased by the ECU via the quantity servo to return the engine to the requested RPM. Fine fuel tuning via the MAF is pointless. I have explained why the MAF is fitted. You believe what you want to. The MAF is there to measure airflow for fine tuning of EGR operation nothing more, now stop being silly.

Datatek · Mar 11, 2014

wammers said:
Keith you obviously do not know how a diesel engine functions. The MAF CANNOT control fuelling subject to airflow through it. Fuelling is dependent on engine RPM and load. If you reduce the fuelling for any given throttle demand the RPM will drop, if that throttle demand is maintained fuelling will automatically be increased by the ECU via the quantity servo to return the engine to the requested RPM. Fine fuel tuning via the MAF is pointless. I have explained why the MAF is fitted. You believe what you want to. The MAF is there to measure airflow for fine tuning of EGR operation nothing more, now stop being silly.

According to you, the MAF just does the EGR, speed, MAP & load also affect EGR according to a recent post of yours. With the MAF unplugged, explain why running is affected? Can't be the EGR if it is blocked. there are 3 reporting the same thing with MAF problems. Not my fault you don't understand electronics.
Bosch seem to think it affects fuelling and they designed the ECU.
You keep adjusting your story to try to cover the fact that things change if the MAF is OC, like the EDC getting confused.

Problem with fuel consumption

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