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Discussion Starter · #1 ·
Hi all i am totally stumped here, well i just got my car emission tested and it flew right through it with flying colours, the car is a 84 Rabbit GTI. The car is running lean and i have replaced the O2 with a new Bosch before my test hopeing that my car will go through less gas, Im only getting just under 300Km (Canada) wich is really bad i think. The only thing i can think of is a bad Aux air Valve, will this cause a increase in fuel consumption? I checked everything no leaks anywere tire pressure is good and filters are all ok and my Temp sesor is working fine. The car runns fine and with the emission test just done the otherday proves to me that its not rich and the O2 is working. Anyone know what can cause such a i consuption of gas???? Thanx alot guys
 

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Re: 84 Rabbit Poor Fuel Economy (Moldavia)

You never mention how much fuel in gallons or liters you use in 300 km which is about 183 miles. How much fuel do you put in to fill the tank?
Compare that to tank size -- 'cause I'm thinking bad fuel guage. If all that is good -- the fuel has to go somewhere -- I'd check and doublecheck all of the fuel lines.
 

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Discussion Starter · #3 ·
Re: 84 Rabbit Poor Fuel Economy (Fat Rabbit)

Well if im correct my tank holds 33 Litre so like 10.5 gallons i think thats the spec for a 84 Rabbit GTI. I have checked the fuel lines and tank and even had my mechanic do a leak down test to check the fuel system but everything was ok. My gas guage is working fine cause as soon as it hits the red mark its really empty when i fill it back up. Can a bad Auxillary Air Valve cause bad gas milage like this? I do notice when i start here up in the cold mornings there just isnt much of a high rev that should be if its cold out, what should it be reving at if the motor is cold first thing in the morning 1200-1500 rpm or more? Im really leaning on the Aux Air Valve but want to make sure before i spend the cash. Anyone else have any suggestions on this?
 

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No real answer i'm afraid but i don't think its the AAR. The only function the AAR has is to increase the idle a bit when cold- like opening the throttle just a bit. Just for reference, my 79' idles just a little bit higher when cold (maybe 100-200 rpm high).The AAR should be closed when the engine is hot, but even if it were open it would just make the car idle too high (or erratically). All the air passing through the AAR has been metered anyway so the fuel/air ratio should be correct.
. . . in any case 300 km/tank is not really too bad for city or mixed driving.
 
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