z.rose188

New to this site and new to the german car owner world. Start off by saying i am a mopar/chrysler tech at my local dealership for 2 years now, previous have worked on cars all of my life. So im not stupid and am a true mechanic. Okay, with that aside, me and my wife picked up a 01 audi a4 2.8 5v with 161k on it. The previous owner stated he took well good care of the car, in which he did, but the car has problems. Im not expecting someone to diag the car over the internet because i can't either, nor over the phone. But me being new to the german world, either guide me in the right direction as for these things may have be common problems. For 1, we put 93 oc fuel in it as for, that's what the germans call for. Say it goes to the 3/4 mark, we drive it maybe 20 miles, the needle drops down around half way mark. Now we drive like normal people, speed limit, etc. Stop at a stop sign and has a very little rough idle. We take off and start driving again and the needle will bounce back up slowly. Another words, this freaking gas needle bounces around back and for and is sucking up a lot of gas. She drives 46 miles every day and has to put 15 bucks in the tank everyday which is pretty much 5 gallons a day. Ive looks for vacuum leaks, checked plugs, etc and i personally do not see anything to bad. I did do a fuel induction service on it and checked filter/mass flow. There are no codes stored, pending, or active on the car. I did get a Fuel trim back 2 codes the other day but my reader deleted it on its own. Any F***** starting points?

z.rose188

I might 91 OC

z.rose188

I meant 91 Octane****

Pmulls870

Are you actually using that much gas? Does the exhaust smell like raw gasoline? have you noticed any leaks? The best place to start is complete replacement for all of the vacuum hoses and give the Emissions system a once over

z.rose188

Yes its using that much gas, it is sucking it down bad. The exhaust doesn't smell bad to me and i have not seen any leaks. I've tested by starting the vehicle and listening to the engine bay for hissing sounds and spraying throttle body cleaner on all vacuum lines and the engine never idles up high.

Highmile

I assume you gave it a good tune up, if you did the injector cleaning... What did the old plugs look like?

Idle it for a few minutes and search for a pinhole in the fuel line? The issue you describe is very weird, I'm surprised this thing runs alright while getting sub 10 mpg Hummer fuel economy...

Maybe a bad ECU dumping tons of gas, but rule out other possible causes first.