03-03-2020, 05:16 PM | #1 |
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Car running lean
So originally thought my stage 1 tune was causing my car to run lean but it appears its something else. Car has new spark plugs and was just at the BMW dealer getting a new passenger side fuel pump (bank 1) which they thought that solved the issue. The car is still pulling P0171 and P0174 codes. Sometimes its just one bank or sometimes it pulls codes for both. Any idea what it could be? Car drives relatively fine however it bucks quite a bit from a stop once i hit the gas, very jolty once i hit the gas. It does seem somewhat sluggish as well. Car also puts out a strong gas smell when im standing outside of it. Everytime i get out im like "damn this thing is stinky"... I was thinking possibly injectors? Anyone else with some insight? Car has 66k miles, bone stock besides charcoal delete and K&N filters.
Last edited by S_CDSM5; 03-03-2020 at 05:27 PM.. |
03-04-2020, 04:35 AM | #3 | |
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03-04-2020, 09:25 AM | #5 |
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Have Checked the MAF and actually cleaned both. The K&N filters are oiled. I could try giving them a good cleaning again. Car is at the BMW dealership now, they agreed to diagnose for free. I am sure they will be able to get to the bottom of it. Sick of driving loaner cars, however in a 2020 M340 this time. Car is badass
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03-04-2020, 06:59 PM | #7 | |
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remove the engine cover(black plastic with m5 badge on it) post cat would be the one I circled in pic [IMG]undefined[/IMG] https://www.fcpeuro.com cheapest place I've seen. Will probably be listed as downstream o2
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03-05-2020, 10:36 AM | #8 | |
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03-05-2020, 10:58 AM | #9 | ||
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03-08-2020, 07:36 AM | #11 |
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Really surprised a post cat O2 is causing those codes. I wouldn't be surprised if it doesn't fix the problem. Also, you really should replace them in pairs. (Do both banks at once). If you have 66k miles your precat O2's are due for change as well. I noticed an improvement in driveability when I changed mine at 65k miles.
If I was looking at the O2's as the source of lean codes, I would be changing the precat sensors first. Based on mileage, I'd be doing them anyway and killing 2 birds with one stone. Just my 2 cents. |
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M5Rick61790.50 |
03-08-2020, 01:24 PM | #12 |
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I agree with you. I thought it was weird the post o2 sensor was even going bad. Maybe pre but not post...maybe a bad catalytic converter? Wouldn’t think any of this would be happening at 66k. I had the car at one bmw dealership last week that said post o2 sensor and I just dropped the car off at another nearby bmw dealer to get a second opinion. If they say the same then I’ll replace the post o2 sensor and see. At this point I’m tired of dealing with this cars faults and issues and may trade it in on something simple like a 2020 M240 or something.
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12-08-2020, 12:41 AM | #13 | |
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12-08-2020, 03:02 PM | #14 |
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02-23-2023, 04:43 PM | #15 |
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02-24-2023, 03:53 PM | #16 |
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Have you tried to revert back to stock / no tune. If you undo the tune and everything is fine, it could be the tune.
I know they replaced the fuel pump but depending on the tune you might need some new gear. Have you tried reverting back and do you have the same issue. |
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02-26-2023, 05:55 AM | #17 | |
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02-27-2023, 06:40 PM | #19 |
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There is no fuel smell with mine. Just one bank showing negative and one bank positive. I guess the injectors could be going out but not enough to cause drivability issues now.
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