Just purchased my first audi. 1997 A4 Avant 1.8 Auto. Not exactly a speed machine, but I really like it. Drive nice, lots of room in the boot, and looks good. Everything I need.


The only thing thats got me annoyed, it that (IMO) it seems to be drinking fuel more than it should. I'll get about 420km out of a tank, which is roughly about 7.6km per liter. It seems like a lot for a 1.8L engine to me. My previous car, which was a 1.6 was doing more like 14kms per liter. I'm not expecting the audi to do that well, but somewhere in the middle would be nice.

How many KM's do you guy usually get out of a tank, and do you have any suggestions as to what the problem could be? I've taken it to a mechanic who's pretty good with Audi's, and he couldn't find anything that could be causing it.

It could be in my head, but it smells like its running too rich to me.

 

Definitely on the low side depending on how you drive. I usually get about 23.5 mpg combined, and I think what you said was converted to about 17mpg? A couple things might help, fuel injector cleaner, new spark plugs, new/clean MAF, and a pre-cat o2 sesnor. Do you have codes for anything though?

 

I'm throwing a code for my 02 sensor in my cat...I have a testpipe so would replacing the sensor even help me out?

 

It wont help for a post cat sensor as far as I know, only for a pre-cat. The pre-cats job is fuel mixture and the post is to check emissions and efficiency of the cat.

 

I'm logging a pretty consistent 21mpg mixed. I've recently replaced my MAF, spark plugs, and coil packs. Should I look into replacing the front O2 sensor at this point?

No CEL's (at the moment lol)

 

Yeah, that works out at about 17.5mpg. I commute to work everyday in the car, so i'm probably doing about 60/40 open road to town driving.

Pre-cat is the one that sits in the air intake pipe after the air filter? The mechanic said that was gunked up and he cleaned it out when I took it into him, but it made no difference.

What do you recommend for fuel injector cleaning. I've seen sea-foam and subaru upper engine cleaner is quiet popular; I was thinking about doing that anyway, but not sure what product is best.

What do you mean by, do I have codes for anything? You mean like error codes; if so then no.

 

Precat is between the turbo and cat. And are you sure you don't have any codes? Just cause you do not have a CEL doesn't mean you're not throwing codes.

 

What you described is the Mass Airflow Sensor (MAF).. these are expensive unfortunately but can cause problems. The oxygen sensors are located on the exhaust. A VAG COM or something that can log realtime engine data is nice to try to diagnose MAF problems. Spark plugs are cheapest and what I would change first (Single tip copper NGKs are what is recommended bkr6e), they are like a couple bux a pop. Like explained above, just because you dont have a CEL doesnt mean you dont have codes, so it is a good idea to plug in a reader.

 

I don't have a turbo, so I guess that rules the Precat out

I'll see if I can find someone local with a reader to see if i've got any issues there, and I think i'll run some injector cleaner through this weekend too.

 

Well if you dont have a turbo, its between the exhaust manifold and the cat, almost any cars got one.