28mpg after service?? WTF!

[NathanA4Avant]

Hi all,

My 03 A4 Avant 2.0FSi went in for a full service recently. Done and dusted, the lumpy idle was chased down to a dodgy injector on cylinder 1.

Was told probably best to change the injector, so had it booked in. Last week it had the work done, and now when scanned apparently cylinder 1 is fine, and cylinders 2-4 are reporting minor misfires (they were perfect before).

Car doesn't judder or feel overly lumpy any more so mechanic said to try injector cleaner in the next tank of fuel and see how it goes.

Ever since the time between service to injector replacement (4 weeks) its been returning 27.mpg. After injector cleaner its slowly risen .1mpg a day, and i'm now on 28.3!!!

Any idea what the hell is going on with my Audi?? Was giving me 32mpg when i got it, and its slowly got worse until the recent running problems engine management light appearance made me spend some money on it.

Do i need to book it in to have the other 3 injectors changed (even though they were fine when checked previously) at £500??

Help please.

 

[beachbuggy]

When they did the service I reckon they either unplugged the batteries or cleared the dtc's from the ecu. This'll reset the ecu and the adaptive channels so it will take a little time for them to return and thus the settings you had before to come back. This can affect mpg .

 

[NathanA4Avant]

My dash pod is knackered anyway. Temperature gauge doesn't work, so when they reset everything, i now get DEF. displayed instead of my trip miles - really annoying!!

Thanks for the reply. Hopefully it starts to sort itself out.

 

[marktdisport]

if the temp gauge isnt working doesnt that effect the fuel economy ???? my 1.8t cupra had temp sensor failure and my mpg dropped 4-5mpg when i had it checked on vagcom it was temp sensor the garage i use said this would alter my mpg as the ecu isnt recieving the correct value info and thinks engine is cold still

 

[beachbuggy]

Not the gauge but the sensor will. If it reads lower temps than actual then it will add more fuel due to colder temps till it warms up.

 

[marktdisport]

thats what i thought but im thinking the temp sensor is the gauge fault and not the dash in my opinion unless he defo sure the dash is knackered ????

 

[NathanA4Avant]

I have replaced the coolant temp sensor twice (one from Eurocar parts and one genuine from Audi) and neither made the dash work. When scanned by the garage it comes back with dash fault. DEF. displayed on dash so assume the gauge is knackered.

I have always thought it was running rich as if the car thought it was cold all the time, but i was still getting 32 mpg - not great but bearable, now its at 28 it sucks - i spend 60 quid a week on fuel and hardly drive it (get lift to work so its only used evenings and weekends - all local trips)

 

[marktdisport]

30mpg is pretty good for 2ltr fsi though m8 time for a diesel me thinks

 

[Turkster]

iv got a pod if you need one, let me know and i can give you the part number on it,

 

[brownie 25]

if the temp gauge isnt working doesnt that effect the fuel economy ???? my 1.8t cupra had temp sensor failure and my mpg dropped 4-5mpg when i had it checked on vagcom it was temp sensor the garage i use said this would alter my mpg as the ecu isnt recieving the correct value info and thinks engine is cold still

is this the case with 1.9tdi,s ?

 

[beachbuggy]

Yes, all cars all makes.

Well all injection cars that is. Anything run by an ecu.

You could also get bad mpg because of a bad maf, bad fpr, or vac leak.

 

[marktdisport]

Yes, all cars all makes.

Well all injection cars that is. Anything run by an ecu.

You could also get bad mpg because of a bad maf, bad fpr, or vac leak.

AGREED MATE !!!! these make big difference's in feulling and economy......

 

[NathanA4Avant]

Vacuum hoses replaced.

May change the MAF, whats the fpr?

Both relatively easy to change?

and Turkster, Is it the whole dash pod? What number do i need to know?

Cheers for the input so far guys. Next attempt is to fill up with some V-power. See if that helps things along.