Very High Idle At Startup, 17.3mpg Combined Gas Mileage And Cel With T

[Ando55]

Hey guys, I used a diagnostic reader on my 2001 ES300; 161,000 miles and pulled a code of P0446: EVAP Emission System Circuit malfunction, I believe that has to be with Vacuum Control Valve along with the Vapor Pressure VSV and the charcoal canister. The car is only averaging 17.3mpg combined mostly highly and a little city driving every day, when started up cold it idles very high jumping to 1800rpm and drops to 1500rpm and slowly works its way down to 800rpm or so in a matter or 5-8 mins, I'm thinking it's tuneup time for the car, or should I look into cleanin out carbon? The car was maintained quite well by the dealer I purchased it at(Massapequa)

[nebhusker]

Hey guys, I used a diagnostic reader on my 2001 ES300; 161,000 miles and pulled a code of P0446: EVAP Emission System Circuit malfunction, I believe that has to be with Vacuum Control Valve along with the Vapor Pressure VSV and the charcoal canister. The car is only averaging 17.3mpg combined mostly highly and a little city driving every day, when started up cold it idles very high jumping to 1800rpm and drops to 1500rpm and slowly works its way down to 800rpm or so in a matter or 5-8 mins, I'm thinking it's tuneup time for the car, or should I look into cleanin out carbon? The car was maintained quite well by the dealer I purchased it at(Massapequa)

Hello - I don't have an answer for you, but I do have a 99 ES300 with 139,000 on it and I get the exact same high idle at startup. It jumps to about 1600 rpm and slowly comes down to normal in just a few minutes. My combined gas mileage mostly city is usually 21-22 mpg in warm weather and 19-20 mpg in cold weather (below freezing). I believe this is normal gas mileage, or very close to it.

So I'm not sure that your high idle at startup and the bad gas mileage are related, at least my experience doesn't support it. If you find an answer for the idle please post it here, I would love to know if it's a problem and what the fix is.

Jason

[92Lex]

A bad gas cap would also throw that code. Check to see if your gas cap is loose or if the seal is dry/cracked.