high fuel consumption

[Pirvu Eugen]

Hy! My friend with the 20v turbo...3B engined V8 with the MRC high boost chip is complaining about very high fuel consumption. About 20 liters at 100km town driving.
No error codes, the car runs smooth and boost ok. What you think? What can cause this?
Lambda probe? Boost leak?
Thank You!
All the best!
Eugen

[prj]

Make sure that the car can roll freely (handbrake, brakes).
After that boost leak test.

[rs200]

Make sure that the car can roll freely (handbrake, brakes).
After that boost leak test.

that is solution too..

well my friend have same problem with his S4 , everithing is pefect on the car,NO boost leek, no faults, no brake problem,new turbo , perfect car , but he can't drive under 17liter / 100km-HORIBLE

and only answer on this problem is high millage engine, his car have over 340 000km.
that can be only answer.

[QuattroFever]

rotten fuel lines? Fuel leak!?

Wouldnt be surprised if they haven't been changed since leaving the factory 15-20 years ago.

Wouldn't throw codes either.

[Pirvu Eugen]

I will check the lines tommorow. Hmmm....PRJ...boost leak? This will not cause running issues?

[prj]

I will check the lines tommorow. Hmmm....PRJ...boost leak? This will not cause running issues?

Maybe vacuum leak.
Check PCV hoses.

[rj scotty]

constantly running rich due to faulty coolant sensor ?

[prj]

Also an option - but first check mechanical things.
IAT and Coolant temp sensors should be verified using measuring blocks.

[driftin jo]

Is the compression OK ?
Low compression will give you very poor fuel economy but may not give you a great loss of power at WOT . I have seen engines perform good at WOT and give good results on a dyno but fuel economy was bad and low compression was the cause.

[rs200]

also the dirty fuel injectors can make this..

[newsh]

Lambda ?

[Phil Payne]

Lambda ?

30,000 mile item at most.

[Pirvu Eugen]

ok.... soo..
no vacuum leaks, no boost leaks, compression is 140 psi on all cylinders...the engine has 370000 km though....i changed 50000 km ago the piston rings and rod bearings.
The coolant temp sensor and IAT sensor checked out ok...measured at the ecu terminal.
No fuel leaks from the fuel lines. I couldint measure the lambda because i didint had the vagcom or oscilloscope with me but i disconnected the lambda probe green wire and reset the ecu.
i will wait the feedback from the owner iff the consumption goes better.
i will send 5 injectors for ultrasonic cleaning...
Is possible that a bad Maf can cause this? The car had an K&N oiled filter on....even the engine dosint jerq..or.cut...

[rs200]

I think that you know - MAF must be clean - he is first stage of checking when engine is thirsty too much.
clean the TPS, he is also matter .

[Pirvu Eugen]

Thank you guys! I will try and let you know!
Regards!
Eugen