Check the gas cap integrity and that its tight. If its been a while since the plugs were replaced, pull, check and replace if necessary. Check the condition of the wires also. After plug replacement, clear the codes and drive it. If your scan tool can watch the drive cycle monitors, watch them while you drive. All except EVAP should drop off and set to ready after about 25 miles. The EVAP monitor will take 2 drive cycles with a key cycle in between to set.Hello,
I have a 99 Outback AWD and it "Stumbles" during acceleration. I currently do not know why it stumbles but took a OBDII read while driving. If any one can help diagnose this problem that would be great. Here is the reading.
Trouble Code - P0440 (Evap sensor)...... Probably the gas cap.
Fuel System 1:
Closed Loop
Fuel System 2:
N/A
Load Value:
12.0%
Coolant Temp:
186 deg F
STFT - Bank 1:
-14.0%
This means the computer is reducing fuel due to the AF sensor reporting rich most of the time. Unburned fuel exiting the engine. Tune up time most likely.
LTFT - Bank 1:
7.8%
Fuel map learning is adding fuel, but this depends on a few factors you don't have listed here. TPS position, MAF and rear O2 are needed for certainty.
Manifold Pressure:
9.3 in.hg
Vacuum is good. This is not indicating a leak anywhere.
Engine RPM:
2450 RPM
Vehicle Speed:
42 MPH
In the last set, the engine temperature was up but the system was still in open loop fuel. The ECM was "learning" it's fuel trim map.I cleared the ecu too. Why?
Doesn't hurt. You ought to be putting it in the tank every 15k miles to keep the system clean.I recently filled up my gas tank so added some sea foam. Is that OK?