Very thirsty car...help!

CJA318T

Registered User
Guys,

Maybe it's me being a hypochondriac but my car seems to be getting thirstier by the day!!

Had my 2001 A3 1.8T Sport for around 3 months (always use shell v-power). Early days i remember mpg around town to be close to 30. Now i can barely get 22. Also within the first few minutes of driving, the power delivery in boost is uneven, tends to surge quite a lot and idles lumpy. Could these problems be linked?

Would the MAF be the likey candidate?
I know aircon draws mpg but does radio or cd player?
Am i being a big girl and is 22mpg alright?

Any suggestions would be great! Thanks
 

rodenal

Registered User
MAF's ususally the first thing to check - unplug it and see if the running improves, if so then thats your culprit.

I'd be expecting close to 35mpg from a 1.8T
 

CJA318T

Registered User
will try unplugging the maf.....

to ask a stupid question...do i literally just unplug the electrical connector going into the maf and leave the maf secured in it's housing? Will that throw fault codes everywhere...if so how do i get everything back to normal when i plug it in again?

cheers
 

petewon

Registered User
yeah just take the plug off. Will probably throw up an ESP light if you have one (does on my A4). Not sure if it will log any codes. And yeah plugging it back in should turn any lights off, if any come on that is.
 

jojo

Looking for Boost!
Staff member
Moderator
Also check your DV, might be a good idea to do a diagnostic check on your car with vagcom or similar.
 

Jampublic

Taking it easy..
Recently unplugged my MAF due to poor running, the car goes like stink now! :faint:

Will fit a new MAF at the weekend and hope it runs just as well! :)

I think you may have to clear the fault codes with VAG though!
 

nickelvery

RS4 B5 380bhp
petewon said:
yeah just take the plug off. Will probably throw up an ESP light if you have one (does on my A4). Not sure if it will log any codes. And yeah plugging it back in should turn any lights off, if any come on that is.

Is this not strange?

How does the MAF have anything to do with your ESP?

Am I wrong?
 

CJA318T

Registered User
thanks for the suggestions guys.

think i will try and unplug the maf first.

jojo...how would i check the dv?

chris
 

petewon

Registered User
nickelvery said:
Is this not strange?

How does the MAF have anything to do with your ESP?

Am I wrong?
Yep it is strange, unplugging the EGR valve will do it too. Not sure why, it just does.
 

CJA318T

Registered User
are there any dangers of driving without the maf?

i'm guessing it's a 'drive as far as it takes you to notice any difference' kinda job is it and not overdo it?

just thinking whether it's worth me doing it on the way home tonight (20mins journey) but lots of stop start idleing?

i'd be screwed witrhout this forum..cheers guys
 

petewon

Registered User
I wouldnt like to reccomend doing it for 20 minutes, might be ok, might not. Ive done it in the past but just long enough to see if the problem has gone. If it turns out to be the MAF it may be worth while trying to clean it before going out and buying a new one.
 

Jampublic

Taking it easy..
Unsure of possible damage, but been running mine for 4 days with MAF disconected! No problems yet apart from burns loads more fuel, which would explain why is running faster due to over fuelling!

As for disconnecting the MAF, it always throws up an ABS light & Engine management light! Unsure why, but done serveral searches and seems to be the normal thing to happen. :faint:
 

CJA318T

Registered User
So if disconnecting the MAF makes the car guzzle fuel (Jampublic), mine already doees that.....what difference would unplugging the maf do to my mpg?

if the maf is the problem, would my mpg improve when unplugging it or would i just get a smoother ride?

rock on!
 

jojo

Looking for Boost!
Staff member
Moderator
CJA318T said:
jojo...how would i check the dv?

chris

Diagnostics will show a DTC, if the DV is faulty. I have a boost gauge on my car, so easier for me lol, new ones are like £22 from Audi I think.
 

CJA318T

Registered User
to clarify from earlier.....is 22mpg sucky (A3 2001 1.8T Sport) for start stop traffic (Ave 20-30mph) to work or am i expecting too much?

Parkers says 35mpg (combined)....what is reasonable mpg for 1.8T?

cheers
 

Voodoo

Registered User
I get 30mpg in mine :sadlike:, 2mile trip into work 10min drive, usually head out for long distances twice a week and at weekends, but im a tad heavy footed :racer:
so im not too supprised. But I would of thought 22 is a tad low.
 

dan_a3

Registered User
forgive me for being old fashioned, but i take it your air filter is reletively clean and not clogged up??
 

shineydave

Registered User
to clear up a couple of issues......

Unplugging the MAF puts on the ESP and ABS lights because the ECU uses the reading from the amount of air going into the engine to calculate the torque output so when a wheel spins it can reduce the torque to prevent spinning, unplugging the MAF removes that reading so the ECU pops the ESP light on. since the ABS and ESP use the same wheel speed sensor the ABS comes on in sympathy.

unplugging the MAF just forces the car to run in a basic map hence if you have a faulty MAF unplugging it will make the car run better. you could run on an unplugged MAF indefinately without causing damage as the parameters are designed to be safe.

diagnostics won't show a DTC for a faulty DV. what it will show is a difference between requested and actual boost, or possibly an overboosting DTC. from that you'll have to do some detective work to find out where the boost is leaking. the DV doesn't have any direct connection to the ECU so it can't be monitored
 

jojo

Looking for Boost!
Staff member
Moderator
CJA318T said:
to clarify from earlier.....is 22mpg sucky (A3 2001 1.8T Sport) for start stop traffic (Ave 20-30mph) to work or am i expecting too much?

Parkers says 35mpg (combined)....what is reasonable mpg for 1.8T?

cheers

I get 25mpg driving to and from work in my 260bhp S3, and it's running heavy 19" rims and Quattro, so I'd expect 30mpg from yours!
 

Starry

S3 8V saloon... APR Stage 2....(-:
22mph from a remaped s3 and 28ish on a run, but my foot is made of a very heavy substance:rockwoot:
 

CJA318T

Registered User
balls!

i definately have a thirsty car then. will try the maf tonight and go from there

cheers guys
 
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