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Hey, I posted a while ago about the 2006 Scion Xb 1.5L with 234K miles.
No codes recently. Did have P0420 Cat Code and had it replaced. After the repair I still had rich fuel trims and asked if it could get looked at. They did and said it was the MAF. They changed it, got it back and my OBD2 scanner still shows running rich. I disconnected the battery, 30 minutes later hooked it back up and started the car. LTFT was at 0, but STFT was a -8, then after a while -15, then after a longer while the LTFT started to drop to -8. When I start to speed up it drops to -20, but once at cruising speed it stays around -12, then idles at -8.
Also, the Downstream O2 sensor sometimes stays around 0.7, then at times at 0.5, then at few times at 0.1. The Upstream sensor does jump up and down. I can't see both O2 sensors and Fuel trims numbers because I have a very basic scanner. Did use the scanner in different cars and Fuel Trim numbers look normal.
There was a hesitation or stutter before, but once the MAF was replace I don't feel it anymore. The car idles fine, around 780, and it has always run fine even with the P0420. A year ago it did have a P012 and I replaced the Oil Control Valve and it hasn't come back. 4 years ago I had to replace 2 coils for the spark plugs, used some parts store coils. I smell no gas or nothing abnormal.
Any help to point me in the right direction would help
Also, would getting the book be good for someone like me that is just really a diyer with a simple scan tool.
- Leaking injector/s when is closed
- Leaking injector/s when is operating
- Vapors from fuel tank (canister purge valve)
- Contaminated engine oil with fuel.
You can try to force the o2s lean by pulling a vacuum line and see if the trims get better.
Pinch off the purge valve hose and see if they get better, but I think your canister would have to be full of gas for it to make the mixture rich instead of lean.
An injector balance test will help rule out injectors.
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