Have you deleted the oil trap completely? I would take a look at the live engine data with your scan tool. Both of the front oxygen sensors (B1S1 and B2S1) should be fluctuating voltage from 0.2v to 0.8v at a pretty fast frequency. That is normal operation, if either of them is stuck at a low voltage, (below 0.450v (450mv), that's indicating either a vacuum leak or a bad sensor. With a vacuum leak, the condition will improve at higher rpms (2500 and up).
The Long Term and Short-Term Fuel trims will start to return closer to zero. Right now, with a lean code, the fuel trims are going to be a high positive number (for example +15-20%) (LTFT and STFT). Positive numbers mean the engine computer is adding 15-20% more fuel to compensate for the lean condition. If the numbers start going down at higher rpm you know its a vacuum leak. If they don't, then you need to see what the oxygen sensor voltages are at. If a bad sensor is flatline below 0.450v the ECM will continue to add fuel because of bad sensor data.
Another possibility is a leaking intake manifold gasket, you mentioned it got worse as it warmed up. Some intake leaks will get worse as the intake itself warms up and the leak size increases, because these are plastic intakes, they expand and cause leaks when hot.
So, the first thing to look at when the problem is occurring is the Oxygen sensor voltages for both Banks Sensor 1 (that's the front oxygen sensors) and the Long Term and Short-Term Fuel trims. Check them both at idle and at 2500rpm. And note the voltages and Fuel trim percentages.
In the diagram below is what the oxygen sensor voltage should be doing when operating correctly. If it's stuck low, that's what is setting your lean code for Bank 2.
Vacuum leaks are very common, for now I would concentrate on the lean condition, and not the oil you're seeing in the intake, a bad vacuum leak is going to lower intake manifold pressure and not pull as much on the PCV system. So figure out the issue that setting a code first, you may still end up with an Oxygen sensor code, because they will usually take a couple of drive cycles to set a code. More than one test drive. Read through the guides below as well.
The clue here is really what the fuel trims are at idle and 2500rpm. Thats what will determine if this is a vacuum leak or sensor issue.
I've added some service info on the PCV monitor (diagram 2) and on the P0174 code (diagram 3). They want you to verify there are no broken hoses or lines for the PCV system. And that they are secure and not leaking. If needed you should take it somewhere and have a shop run a smoke test on the intake manifold to check for any leaks, it's the most effective test.
https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers
https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge
https://www.2carpros.com/articles/7-common-symptoms-of-a-vacuum-leak-in-your-car-how-to
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Sunday, March 3rd, 2024 AT 11:45 AM
