Hi all. I need your help. I bought Audi A4 with 74kW PD engine and I have a seious problem with fuel consumtion.
We know that this car may have consuption around 5-6 liters per 100km, but my car have around
8-9 liters. There must be some problem with the engine. I have a Octavia 1.9 TDI 66kW too, and there I have consumption around 5 liters. But I would like to ask you if you will know possible reasons.

Our idea was that there is problem in injectors, becouse engine has 260tkm. So we change the
engine head with injectors from good engine, but consumtion is still
same (other engine was same type and year).

Or have you some other idea why is consumtion so high? We have last
thing what we want to do, change the temperature sensor on the engine. But its last thing we have on mind.

Car is going well, no smoke. Of course, we used VAGCOM to diagnose the
car. There are no errors, only in measurments, engine idling speed is
little higher, 882rpm. When measuring the fuel injecting, on channel
008, there are three values in fields 2-4, which are 60,70,60 on 3rd
gear, 3000 rpm, full load. I think these values are about 1/3 higher
than normal. MAF sensor is 940, turbo 2162.

We would be happy for any tip you will give us where can be the
problem. Thanks much.

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Mike, Czech

Mike,

My first gut reaction would be a faulty MAF running you too rich. Have you checked the timing graph to make sure it is at the top line? Next, do the injection readings fluctuate irregularly at idle? What is your IQ registering, over 7-9mg per stroke? Give me a little more info and I'll troubleshoot with you. Anything strange about the driveability or repairs done recently? What size injectors are you running, stock? Any chips or ECU adjustments?

Cheers!

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Hi, thanks for help. Yes, there is a chip in the car now, but if there is orifile, consumption is same. So its not due the chip. But you maybe right that there can be wrong type of MAF in the car. It can cause higher consumption, like when you give MAF from 1.8T engine to 1.9TDI car. We will look at number and try to find if MAF is right.

We bought the car in Deutch. Car was 260.000 tkm with this engine. So becouse consumption was high, we have changed the head of engine from the car, which have 70tkm, and consumption is same.

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Mike, Czech

There's not much else that it can be on that type of engine. Fuel flow is regulated by the pump and injectors via info from the ECU which calls for x amount of injection based on MAF info and DBW input. My guess is if injectors are stock and pump is working properly than info on the air flow must be incorrect to the ECU. Problem is that you bought an unknown engine with an unknown history. Always much harder trying to sort out somebody else's problems. Check to make sure they didn't rig a pot/resistor to the wiring harness on the fuel pump. Sometimes people will do that to trick the car into raising the fueling to increase power.

Good luck!

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