[maximoline]

Hey guys. This is my first post on here. So the other day my bmw started idling like crazy and the service engine soon light came on. I got scared and ordered all new spark plugs, and ignition coils from fcpeuro. But when I went to change them I noticed oil in the spark plug well unfortunately. So that same day I also ordered a new valve cover gasket and all new seals on it. After I finished replacing everything I started my car and it still had the idle. The day after I started it again and the idle was gone. Now it’s been a week and it seems to drive fine but when I put it in reverse or park the rpms are all jumpy. I’m not sure what to do, could this be a faulty fuel injector? I have a bmw e92 328i N52.

[clegg]

Pull codes from the car and post back.

[tcphoto]

Typical response is to spend too much and replace unnecessary parts, odds are you have deteriorating vacuum hoses which caused lean codes, P0170 and P0171.

[relative4]

Wow, that's quite a barrage from the parts cannon with zero diagnosis.

[MightyMouseTech]

Originally Posted by tcphoto

Typical response is to spend too much and replace unnecessary parts, odds are you have deteriorating vacuum hoses which caused lean codes, P0170 and P0171.

Vacuum hoses?

OP, what do you mean idling like crazy? Idling is normal?!?

[maximoline]

Originally Posted by MightyMouseTech

Vacuum hoses?

OP, what do you mean idling like crazy? Idling is normal?!?

I meant very rough idling like the car was shaking. Sorry about that. I’m gonna pull codes then post them in a second

[maximoline]

The codes were P0306 cylinder 6 misfire

[marvinstockman]

What did the plugs look like when you changed them?

[MightyMouseTech]

Originally Posted by maximoline

The codes were P0306 cylinder 6 misfire

Only one code? I would check for oil contamination in your eccentric shaft sensor connector.

[maximoline]

update, my service engine soon light went away but it still feel a slight shake and the rpms slightly fluctuate when i turn the car on in park

[zipstic]

Originally Posted by maximoline

update, my service engine soon light went away but it still feel a slight shake and the rpms slightly fluctuate when i turn the car on in park

Are the RPMs only fluctuating during a cold start?

On a cold start the RPMs should be around 1100 or so for the first 30 sections and then come down.

If you're getting fluctuating RPMs, how much does it fluctuate?

[lowrydr310]

Originally Posted by maximoline

update, my service engine soon light went away but it still feel a slight shake and the rpms slightly fluctuate when i turn the car on in park

It's hard to diagnose with just the basic codes you pulled. A #6 misfire could have been a bad coil or plug, or it could have been caused by something else. (On the other hand if you never had a record of plugs or coils having been changed since you owned the car, it's not a bad thing that you have fresh ones installed now, there's no harm to anything but your wallet, and now you know they're good).

You need to read the BMW-specific codes, and you'll need more than a basic code reading tool for that. The cheapest option is to buy a quality K+DCAN cable (bimmergeeks is the one I used, around $40) and then download free INPA software on your laptop. However there are numerous other options, many of which are even easier to use.

I think I know the behavior you're describing with the bouncing idle. When you put the car in gear and the RPMs will bounce, like the engine is stumbling and then recovering. This might be related to the VANOS system; whether it's the VANOS solenoids themselves, the check valves, or the eccentric shaft sensor. If there's a problem with any of these, they'll usually trigger a BMW-specific code which can be read with the proper tools as I mentioned above.

I experienced this bouncing idle a handful of times and even once got an intermittent VANOS-related code (don't recall offhand exactly what it was - it didn't trigger the SES light however it was stored). I removed and cleaned both VANOS solenoids and the check valves. While not blocked with sludge, they all had a mild dark varnish on them which came off easily with some carb cleaner. Since cleaning all of them and doing several short interval oil changes (5000 miles) I haven't experienced the jumping idle issue at all.