1999 camry poor gas mileage

[drgphilip]

Hi All,

I have 1999 camry well maintained with oil changes every 3500 miles. It was giving me an average 22/28 mpg until about 2 months ago when it dropped to 17/26. I checked the air pressure .Everything seem to be OK. Two weeks ago, the check egnine sign came and I checked the code- P0171.Replaced the front air fuel sensor.Check engine sign gone but the gas mileage same.
Now I have one more problem after the air fuel sensor change. The engine sound is much higher and rough for about 3-4 minutes when the engine is cold started. It comes down after the engine is warmed up.
I need inputs about poor gas mileage and the higher engine sound. Does this indicate anything major ?

Thanks all


phige

[freestylez]

um maybe its because of the cold weather and the usage of the heat ?

[cdncamry]

I have the same symptoms, and would be interested to hear any input.

[nodrogkam]

so you're saying that year round you get 22 mpg, no matter if its cold warm or hot? Typcailly in the winter months MPG goes down due to the cold. Your higher idle, unless over 3000 rpms isnt too unusual when temps are 0-10 C. My camry cold start idles at about 2700rpms and slowly go down. Your higher idles could also be due to the new sensor. Did you disconnect the battery to reset the ecu when your sensor was replaced? It sounds to me like your computer hasnt adapted to the sensor yet and its trying to take in too much air. I guess i am more concerned about the rough idle part. Do you mean the car shakes? RPM's fluxuate?

[ToyotaToday]

If its a sudden drop in mpg like this, it sounds like ECU or sensor problem.

[drgphilip]

Thanks for the thoughts,

I bought this camry second hand about 2 yrs ago. After that I was getting the mileage I mentioned earlier on an average irrespective os winter or summer (until about 2 months ago).
No car shake/ RPM fluctuation. RPM is around 2800 on cold starting . It comes down gradually to 1800 in 3-4 minutes of idling.
When the sensor was changed the ECU was not disconnected from battery.
I also thought about ECM not adaptting to the new sensor. Will just resetting the ECM at this point benefit?

phige

[drgphilip]

Originally Posted by nodrogkam

so you're saying that year round you get 22 mpg, no matter if its cold warm or hot? Typcailly in the winter months MPG goes down due to the cold. Your higher idle, unless over 3000 rpms isnt too unusual when temps are 0-10 C. My camry cold start idles at about 2700rpms and slowly go down. Your higher idles could also be due to the new sensor. Did you disconnect the battery to reset the ecu when your sensor was replaced? It sounds to me like your computer hasnt adapted to the sensor yet and its trying to take in too much air. I guess i am more concerned about the rough idle part. Do you mean the car shakes? RPM's fluxuate?

[leasaunce]

check the PVC VALVE

[drgphilip]

I replaced the PVC valve at 65k. Now my car has 80 K on it. Should I be concerned about the valve at this time?

[leasaunce]

^ just try cleaning the PVC Valve again. but dont think that will solve your prblem, IT MIGHT HELPS!

[nodrogkam]

heck i say just reset the darned thing anyways. It doesnt hurt anything. Disconnect battery for 15 minutes then reconnect. You'll loose your radio presets but besides that it should affect anything.

[ToyotaToday]

Yes, I agree. Disconnect the battery so it resets. Your car may be shifting at higher RPM's, gone into "sport mode".

[drgphilip]

Thanks guys,
I will disconnect the battery and reset the ECU and get back to you

phige

[tarbasd]

You say your idle goes down to 1800 after 3-4 minutes? That's seems to be still way too much. On Gen3 A/T idle is 800 RPM.

[Gary_602Z]

A bad thermostat or ECT sensor for the computer can cause bad mileage. I would check there first.

Gary