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Rough idle and poor fuel milage

Discussion in 'E46 (1999-2006)' started by alfabmw, Jan 14, 2011.

    • Member

    alfabmw

    Post Count: 9
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    Hi everyone,

    My car (2001 325xi) has a couple of issues that may be related.
    1) When the weather started to get colder in December, I started to notice a slight decrease in fuel economy. Now that it is colder still, it has gone down further. Last check it was about 19mpg, in the warmer weather it was probably 23 or so.
    2) Also since it turned colder the car has idled roughly on start up. This has happened maybe 6 times or so since November. If I shut the car off and then start it back up, it idles fine and drives normally. Thursday morning I jumped in, started it up and it was rough. I am a call firefighter, and I was responding to a call so I did not take the time to re-start. I got a little ways down the street and got the check engine light on, and the car did not want to go above 20 or so. I pulled over, shut the car off and re-started, and took off down the street as if nothing happened.

    I changed the plugs about 2 weeks ago, but have not noticed a change. I am going to check for codes over the weekend, and change the air filter. I think I will also put some injector cleaner in the tank. It seems like the computer is getting wrong information or getting confused, since a "reboot" seems to fix it.

    any ideas would be appreciated!

    thanks,
    Russ
    • Member

    floydarogers

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    • Member

    alfabmw

    Post Count: 9
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    Thanks, I just checked the codes, and got a P1347, which points to a misfire in cyl 3. I will try swapping it with another, and see what happens.

    europeanautorepair guest

    Post Count: 1
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    Look under the intake manifold. There is a oil air seperator. The bottom hose to it goes to the oil dipstick tube... follow it there and make sure its the rite one. once you know its the rite one follow it back and see if there is a tear in it anywhere. We see this all the time in our shop. Very common. Also could be a coil, but check that hose. Any questions email me at gvillelube@yahoo.com
    • Member

    alfabmw

    Post Count: 9
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    Thanks, if it ever stops snowing and warms up, I will take a look at that. Since my initial post, the problem has not come back, and the car idles smoothly. I have changed the air filter and added injector cleaner since then more for my milage concerns than anything else.

    Russ

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