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So I have a 2000 Corolla ve and the check engine light is on and it is p0171. System lean bank 1. The issue I’m having while drive (which is at random) is I’ll be driving the car and out of know where it will feel like it’s cutting out and not getting fuel. And so I let off the gas and sometimes it will keep jerking and feeling like it’s not getting fuel, but it will always stop and then it will be fine. Or I can go days with no issues at all. The things I have changed are he intake manifold gasket, cleaned the maf sensor multiple times, changed the front o2 sensor with a denso unit, changed the spark plugs, changed the pcv valve, and changed the coolant tempature sensor. When I first changed the intake manifold gasket the engine light turned off after so many miles. And then eventually came back on. I’m not sure where to go from here. I do have a massive exhaust leak where the donut gasket is due to the exhaust just rusting out and be 17 years old. I know I’ll need a who new header due to the bolts be stuck and having a huge gap and whatnot. I don’t think that would cause my lean code though. Also one more thing is I did an old school injector test with a screw driver and held it up to my ear and all the injectors sounded uniform and no hesitation. Sorry for such a long message, just trying to be thorough. Thanks guys!
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I have not since I have read that it’s unlikely that it’s fuel related with this generation of Corolla. Not to say that it can’t be the cause. Just trying to start with the easiest stuff first as I have no way to check the regulator. And actually not sure how to check if.
If the exhaust leak is large enough, it could cause the issue. The O2 sensor is what pops this code, so if it doesn’t see the amount of fuel/air mix that it should then it will trip it. I would suggest to test the O2 sensor and check for vacuum leaks.
Check that there aren’t any leaks around the intake where you changed the gasket, and you might want to try a new MAF (OEM, the aftermarket ones are junk). A faulty MAF is a notorious problem on these and cleaning is usually unsuccessful. If you have a scan tool with live data you can check your MAF reading vs engine load and see if the data is good. Also, the fuel adaptions will need to be reset after replacing the MAF. Another possibility is dirty injectors. Just because they “sound good” doesn’t mean they have a good spray pattern.
From what i have read, you need to fix the exhaust leak, you should be able to buy a replacement pipe from rockauto.com, the leak is introducing o2 and messing up the sensor, you may also have a bad leakinge fuel injector, this is dumping more fuel than needed, thus backing off the fuel, causing a lean condition, if you have access to a scanner, you should be able to see if the engine is actually running lean, i also suspect you picked up a vacuum leak, hook up a vacuum gauge and view the vacuum to see how much it pulling, brittle hoses will do that also, check your intake hose for cracks also.
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