yeah,i know its a it is a hose somewhere prob.in the back of the car under the wheelwell skirts.i havn't found it yet.but every time i fill up with gas,any amount,any level,it is hard to start the car,then it regains it's perameters and is fine till next fuelling.i'm really not happy with this car as i've had so many issues with it,it should'nt be this slow,i had a kia rio sedan keeping up with me yesterday.it's a 2.8 30v. i hope when i get this prob solved,all will be well.if not i'm dumping it.i bought this because there is an 85 v.w. golf 1.8 3 speed automatic thats been flawless running in the family for 17 years and has cost no more than $1500 total maint. everything in that time,and is still running stong.i'm its mechanic,and all of my friends best mechanic,this audi is rediculous.latest is the headlights dont turn on immediately,well they do if switch is lightly pulled and held ,then when contacts warm up,they work fine.i have a new multi-switch(dealer wanted $300)i got off ebay for $48(sounds scary but tested well)and the dealer wants $300 to install.i'll prob do myself. so it could've cost $600 to replace a headlight switch.f'n amazing.

 

as you can see P0455 doesn't just mean "air leak" its to do with the EVAP system, when you open the gas cap your triggering a fault at that point (it doesn't matter if your filling up) just the fact you opened the gas cap seems to be causing the fault "have you tried that to see if the problem happens then??" start at the canister purge valve then work your way down the system

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thanks for the reply avant80.yep tried that,i've cleared the code opened the cap driven the car reopened the cap,and no code,i've used 2 different new gas caps,no change.i've put a new purge valve in,checked at evap can for fuel overflow ande leaks w/hoses.i've checked and changed many emissions and vacuum hoses properlyonly areas not checked yet are leak detection pump and fuel tank line assembly.i've checked 0455 history search here and same issue has been mentioned many times with no response when fixed.heck,you've even attempted to help someone with same issue last year.i am a boat and drive(transmission for boat)mechanic by trade,so i'm not a dummy,this one is f'n ponderous.thanks

 

fuel pressure regulator, you are losing the pressure over a short time which causes over fueling also another area to check is pin holes in the pipework that could cause fuel pressure loss

 

cool. ive thought about the fuel reg.might be why car seems so underpowered.thanks

 

very possible it would also cause excessive fuel consumption

 

i get 30.8 on freeway over 60 miles distance.

 

so local you should get less than half that?? depending on speed of course

 

you need to do a fuel pressure test

 

23.7 is my average pretty much steady22.9 lately.just talked to dealership,they say there could be 2 recalls for my car.je is one lk is other. he said its a hose to throttle body issue which requires a new throotle body.