MAF cause of low Fuel econmy and performance

[Ant FR]

In another post i made in the REVO section about hitting limp mode a lot with REVO switched on some clever bods told me to look at the MAF sensor too as this could cause that.

Have'nt tested yet, but would average fuel consumption of 40mpg and lower performance also stem from the MAF being faulty. on a full tank i have been getting around 350 miles recenthly on a mk4 1.9 tdi fr, when it was nearer to 53mpg average and around 450 miles to a tank when i first got it.

cheers

 

[flashbsd]

on a full tank with my knackered MAF im getting about 200 to 37 quid (mk3 ibiza cupra)

Now to be thats silly, thats even normal driving.

I wouldnt be suprised if it made a diff to fuel economy

 

[Johnsey]

In another post i made in the REVO section about hitting limp mode a lot with REVO switched on some clever bods told me to look at the MAF sensor too as this could cause that.

Have'nt tested yet, but would average fuel consumption of 40mpg and lower performance also stem from the MAF being faulty. on a full tank i have been getting around 350 miles recenthly on a mk4 1.9 tdi fr, when it was nearer to 53mpg average and around 450 miles to a tank when i first got it.

cheers

Is that full tank + vented?

 

[Ant FR]

45 litres into a supposed 45 litre tank and not refilling till it gets to the bottom line passed the red

 

[Johnsey]

You should be getting more than that, I get 470 from 40litres (which drops a bit in the summer) and i dont let it get down as far as you do

 

[Ant FR]

so could this be the MAF

 

[Johnsey]

so could this be the MAF

could also be a boost leak ?

 

[micky 32]

Cant see MAF causing limp mode though.

 

[Diablo559]

what should a cupra diesel do to a tank mine is gettin about an extra 50 mile out of the tank since revo. there is days i dont think it goes as well but then it might be in my head

 

[j.a.kelly]

Ant,

when you floor the car do u hear a funny wooshing sound?! not the normal turbo sound but slightly higher pitched? i get 300miles to a full tank usually, which isnt that brill (custom code 1) ive recently had problems with my boost pipe and was loosing boost. replaced pipe and clips but i dnt think the problem is solved, still same noise and play in the pipe where it meets the manifold.

wonder if we have same prob? but my car has 65k on

JK

 

[Johnsey]

Ant,

when you floor the car do u hear a funny wooshing sound?! not the normal turbo sound but slightly higher pitched? i get 300miles to a full tank usually, which isnt that brill (custom code 1) ive recently had problems with my boost pipe and was loosing boost. replaced pipe and clips but i dnt think the problem is solved, still same noise and play in the pipe where it meets the manifold.

wonder if we have same prob? but my car has 65k on

JK

Mine has 73k and had the turbo intake pipes resecured on Friday and they're fooked again already. Which reminds me i must phone the Stealers

 

[Ant FR]

Ant,

when you floor the car do u hear a funny wooshing sound?! not the normal turbo sound but slightly higher pitched? i get 300miles to a full tank usually, which isnt that brill (custom code 1) ive recently had problems with my boost pipe and was loosing boost. replaced pipe and clips but i dnt think the problem is solved, still same noise and play in the pipe where it meets the manifold.

wonder if we have same prob? but my car has 65k on

JK

nope differing noises, just lack of go go

The more i think of it the more i am convinced it is the MAF, i will test tonight by disconecting to see if any noticable gains, then get a new one sorted by the dealers, that way i can then be sure that theris is the problem.

i think i need to look at buying a vagcom cable.

 

[sssstew]

Ant - the best bet is to invest in vag com, you can log the MAF and tell straight away if its dead or dying or not.

and yes a dieing maf could well effect the fuel economy on the TDIs.

 

[devonutopia]

A dying MAF does throw the car into limp mode as well. I guess its just the car throwing a wobbly when it misreads the volume of air coming into the system? Had one MAF die a while ago and it was a pain in the a55! I had to keep turning the car on and off while on the move to clear the limp mode and give me boost again.... Toward the end it was only lasting a few seconds, so I gave up and drove it in limp mode until I could get a new sensor.

 

[Ant FR]

cool. tried it last nigh twith the MAF disconnecte, it would'nt boost at all which was very wierd.

I am gonna invest in VAG com this weekend and see how it all looks, so wait for silly vag com questions coming soon.

 

[LEON_FR]

guys how do you know if the maf is fu*ked?

 

[sssstew]

you know if the maf is fecked by loggin Mass Air Flow requested vs Actual in VAG COM... thats the only way to tell for sure. But if youve got reduced performance and unplugging it improves it then thats also a test for if its knackered.

 

[LEON_FR]

o i see... cheers

 

[muddyboots]

I am gonna invest in VAG com this weekend and see how it all looks, so wait for silly vag com questions coming soon.

You won't regret it.

A whole new world of geeky data will appear

Incidentally, I did a few logs the other night in the Passat, my MAF airflow was reading 1100-1200 (mg/s?) during a full bore run, I presume this sounds about right ?