engine management light.

[ade221]

Hi, i have a 1999 323i e46, after some advice so i dont waste money on expensive dealerships. When my baby is idling after about 2 mins the engine management light comes on and she runs as though she is not firing on all 6, but after driving her a little bit, she then runs fine and after about 10 mile the engine management goes out. Is this a serious problem? please help me because i love my baby.

[Manolito]

My first guess would be a leaking fuel injector that is flooding one cylinder at idle, but at higher speeds, the amount of fuel leaking is not significant to the total fuel flow, so it clears up. Try some fuel injector cleaner (Techron, if you can find it) and see if it makes a difference.

I would let it idle poorly for a few minutes and then shut it off and immediately pull all the plugs and see if one is wet.

IMO, your money is better invested buying a Peake tool and reading the computer code than paying a dealer to do it. That way, if you can't fix it yourself and you go to a dealer, you are armed with information. I also strongly suggest that you invest in a Bentley manual if you want to take care of your car yourself.

[ade221]

Thankyou for that, I will get straight on to it tomorrow, and let you know if I am successful.

[ade221]

Hey, checked the plugs and all seemed cool, so i have ordered a peake tool, just cant wait for it to come, my poor baby needs looking after

[ade221]

I plugged the peake tool in, got about 8 codes, most of them saying misfire in a cylinder or something to do with the air filter (fitted a pipercross). I then reset them and let her idle, and to my amazement it idles cool, does anyone know if the engine management came on because it hadnt been reset before or can i expect it back

[Manolito]

Expect that it will recur. Codes rarely pinpoint the true problem, but the first code it sets is the most informative. Check it again the first time the Check Engine light illuminates.

If the computer gets an error that causes it to disbelieve its inputs, for example, if the water temp sensor says the engine is hot but the oxygen sensors are still cold, it may go open loop which may be too rich for the engine when it is warm, causing it to load up the plugs and run rough. After the codes were reset, the computer went back to normal closed loop operation, and will stay there until it looses a signal or gets a nonsense signal that causes it to disbelieve its inputs again.

You might try unplugging and reconnecting all the electrical connectors you can get to, in hopes of cleaning up a corroded or loose connection. Examine them for corrosion or damaged connectors if you can see into them.

How old are your oxygen sensors? If they have more than 90k miles, you may as well save up for new ones. They will start giving you trouble soon if they have not already. They are pretty easy to replace. They don't cost much if you go with generics, but I have never dared used generics on an OBD II car. I buy OEM Bosch sensors for all my BMWs. (3 cars x 4 sensors each = $$$$$$)

[ade221]

Thanks for you patience, yep, it came back on and same codes, AAAARRRRGGGGGHHHHH!!!!!!!!!!!! I will get onto what you suggested on Saturday. ta

[Manolito]

If you list the codes here, we can see if any of them match up to common problems that we are aware of.