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  1. #1

    Fuel issues - 05 330i ZHP

    I loaned my car to my brother so his daughter could have something to drive after she got in an accident and I got it back with a busted inner tie rod, scraped up wheel, and fuel issues : Also it's a stick shift and I doubt she could drive one of those before. Am I an idiot? possibly. But he's done me some favors so why not.

    I fixed the tie rod and I'm getting it aligned tomorrow, but I have some questions about the fuel issues, because it's complicated... so buckle up...

    It's had a low RPM hesitation since I owned it, and I haven't looked into it since it drives fine otherwise and I have 100 other things to fix on it. I did replace all 6 spark plugs and coil packs last year because it was running rough. The rough running was solved, low RPM hesitation still an issue.

    Fast forward until last month - loan my brother the car, get it back and now my wife is driving it. Twice now she says that after 30-45 min of driving it starts to drive really rough. It started as a rough idle, then it drove really rough on the highway. I got the check engine light code scanned and it pulled P0305 - misfire on cyl 5. It wasn't running rough when I drove it. In fact, I've driven a few hours in it and it hasn't driven rough at all, except the low RPM hesitation.

    I'm thinking my brother's daughter put low octane fuel in it, but would that make it run that rough? In addition, I've been reading on forums that a cyl 5 misfire CEL happens when general fuel issues happen, not just when cylinder 5 is misfiring. I'm going to switch the cyl 5 spark plug and coil pack with 2 other cyl to rule those out in case the running rough comes back.

    How about the lower RPM hesitation? I know these cars have issues with fuel pumps and it has 130K miles and doesn't appear to be well maintained by the PO. I'm thinking about replacing the pump, regulator, and filter. Injectors maybe? I vaguely remember reading somewhere that the fuel injectors were updated or something, but this may be a figment of my imagination.

    Any other suggestions? Thanks for the help, guys. I hate to throw parts at it especially since my house will be done in 1 month and I can't spend much until then. Also, the only tools and garage I have access too right now are at my parents house an hour away. My tools are in my brother's storage unit and he hasn't paid the rent in a while so they're locked up (the favor I was referring to earlier) along with half of all my other stuff :-/
    John||2005 BMW 330i ZHP||1995 Chevrolet Camaro 3.4L||2008 Hummer H2 SUT|| @oltorf.the.destroyer

  2. #2
    Join Date
    Feb 2019
    Location
    W/S, NC
    Posts
    141
    I'm throwing darts on the board here after the usual suspects but I'd start with topping it off again and again with premium, or finding a station that sells 100+ octane to offset the likely hood of low octane fuel being the culprit.

    The fuel filter and regulator are the same. It's under the driver's side. If it hasn't been done, do it. Have new fuel hose, vacuum hose, and hose clamps ready. If you plan on doing fuel pump anyway at least do this at the same time. Some people also recommend replacing the fuel pump relay as well since they can fail.

    Check and or replace your lower intake boot, if original it prolly has a crack in it. While that's out take out your ICV and clean it thoroughly then re-lube it with some clean engine oil. Blow all the excess out and then reinstall. It should click around when you shake it. No clicking means it's gummed up.

    At 130k you could be having soft fail issues with the fuel pump but it's hard to tell without checking pressure at the rail. My 05 has 143k on the stock pump AFAIK, still going strong but it's on my mind for sure.

    While your working on it let it sit with battery unhooked for a while so it'll hopefully clear any adaptation values.

  3. #3
    Quote Originally Posted by Thatguy_JZ View Post
    I'm throwing darts on the board here after the usual suspects but I'd start with topping it off again and again with premium, or finding a station that sells 100+ octane to offset the likely hood of low octane fuel being the culprit.

    The fuel filter and regulator are the same. It's under the driver's side. If it hasn't been done, do it. Have new fuel hose, vacuum hose, and hose clamps ready. If you plan on doing fuel pump anyway at least do this at the same time. Some people also recommend replacing the fuel pump relay as well since they can fail.

    Check and or replace your lower intake boot, if original it prolly has a crack in it. While that's out take out your ICV and clean it thoroughly then re-lube it with some clean engine oil. Blow all the excess out and then reinstall. It should click around when you shake it. No clicking means it's gummed up.

    At 130k you could be having soft fail issues with the fuel pump but it's hard to tell without checking pressure at the rail. My 05 has 143k on the stock pump AFAIK, still going strong but it's on my mind for sure.

    While your working on it let it sit with battery unhooked for a while so it'll hopefully clear any adaptation values.
    Ok, I added a few more things to my very long to do list. Thanks for the advice.
    John||2005 BMW 330i ZHP||1995 Chevrolet Camaro 3.4L||2008 Hummer H2 SUT|| @oltorf.the.destroyer

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