With the complaint of the malfunction indicator lamp (MIL, Check Engine Lamp) on, checking for stored trouble codes is the place to start. Today we'll be using the OTC Encore for the initial check. The tool was just updated and I want to see how it performs with the updates. My main complaint with the Encore in the past has been system speed. The system seems to be much faster now. On with the show!
We have a pretty solid P0496 stored which is described as EVAP system flow during non-purge.
The longer description contains the reason for the failure code. The engine computer closed the vent valve and the purge valve and saw (fuel tank pressure sensor) vacuum being pulled on the tank. There should have been no vacuum.
Evaporated fuel vapors are stored until the purge solenoid opens. When the solenoid opens then vacuum draws the vapors into the engine where it becomes part of the fuel mix. Open at all times is going to upset the fuel mix and cause some driveability problems under particular conditions. "Runs bad at times". I removed the engine cover to access the purge solenoid for testing.
Scan tools these days often have databases of common problems. "Code Assist" is available on the Encore. The most common fix for this code is to replace the purge solenoid. That doesn't mean it is bad, replace it. It means that it would be a good idea to start your tests there since it is the most common failure.
That reminds me, the Encore is also internet friendly. If I wasn't familiar with testing the purge solenoid or with the system I could do deeper digging from within the scan tool without traveling back to the desk computer. Identifix is a good place to take a step further from where we are right now. Since the solenoid is normally closed, disconnecting the wiring and will eliminate an electrical problem.
I used the vacuum gauge so you could see there is engine vacuum at the port when there shouldn't be.
After that it is time to go online to the desk pc, enter the car, find the part I want and order. Kinda like getting pizza.
Always compare the new part to the old.
Also test your new part to be sure it isn't stuck open as well. Always remember NEW doesn't mean GOOD. It just means new.
Everything worked and I put the engine cover back in place. Time to clear engine codes but first we want to look at the data for misfires. The car is approaching 80,000 miles. The spark plugs are reaching the end of their life with a recommended replacement at 97,500 miles. If I see any misfire history I'm going to do a spark plug inspection. If we clear the computer we'll lose the misfire history.
Nothing to see here. Looks like we need to clear codes, do some monitor friendly driving and check for any new codes.
As always, thanks for reading!!
Kenneth Hayes
G&G Auto Repair
Searcy Ar.
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