E90 325i with misfire during cold start and not when hot

[BlownMotorWorks]

Hi all,

I need some help with my 2006 325i e90 N52.
A couple of weeks ago the car started having problems with misfires on cold starts. The vehicles idles fine when it is starts but as soon as the rpm is picked up above a certain point it begins to idle eratic.The car can drive although there is a loss in performance and increase in fuel consumption.After a switch off and restart the problem persist.It will only idle properly after its been switched off for a couple of minutes when it seems it built up some heat.
The fault codes shown refer to the crankcase sensor , inlet cam sensor , misfires on all cylinders. The crankcase sensor was replaced but the problem only returned after a day or so.I also replaced the battery because the battery low sign came on a couple of times. I have been told it could be the VANOS,cold start sensor, mass airflow sensor etc.
Kilos are still quite low at 87000 and BMW did all the services.

 

[Iceman007]

Injectors or head itself

 

[Blue Shirt]

At 87000km, the spark plugs could be at the end of their lives. Spark plugs are normally replaced every 100000km but if your driving pattern is mostly short trips, the plugs could be fubar by now.

I recommend that you install new spark plugs, they are not very expensive. Get the specified Bosch or NGK plugs for your engine.

 

[akash]

At 87000km, the spark plugs could be at the end of their lives. Spark plugs are normally replaced every 100000km but if your driving pattern is mostly short trips, the plugs could be fubar by now.

I recommend that you install new spark plugs, they are not very expensive. Get the specified Bosch or NGK plugs for your engine.

Same here.

You need new plugs. Start there first.

Bmw only change the plugs at around 100 000km (crazy i know)

 

[BlownMotorWorks]

Yes , i agree, that service interval is ridiculous. Especially for short distance driving.I will change the spark plugs and give some feedback.

 

[akash]

Yes , i agree, that service interval is ridiculous. Especially for short distance driving.I will change the spark plugs and give some feedback.

Contact Diesel Electric i believe they have the spark plugs for R124 each

 

[BlownMotorWorks]

Got the plugs and will fit them the weekend, they came in at R103 odd from Diesel Electric. I fitted a new Battery too about a week ago.I read somewhere the system has to get programmed for the battery and registered. Is this true?

 

[Blue Shirt]

Yes, ideally you should register the new battery with the car's electronic system. That way, the alternator and charging system will adapt the charging of the new battery to ensure maximum lifespan.

The battery registration takes a few seconds with the right tools. Find someone with diagnostics tools such as DIS or INPA to do this for you.

 

[Philip Foglar]

Bosch plugs at G-Drive is also a very good price for the N52.

I would start by replacing the plugs and see what happens.

I would also remove, clean and replace swapped around both Vanos solenoids (I posted a DIY sometime ago for this). The problem is with the typical extended oil change intervals causing the oil to start sludging up the solenoids (usually exhaust side is the dirtiest of the two).

I would also invest in some good MAF cleaner and give the MAF sensor a proper clean. Also, a faulty MAF can cause all sorts of similar issues as well as the "heat soak" issue since it measure intake temperature and air-flow.

I would also run a tank of fuel with a good injector cleaner, but I would also have the Smooth Running checked via live diagnostics to ensure that there are no issues there. My car had some muck in the fuel rail that was affecting injector (and cylinder) 1 and causing an over-correction outside of the acceptable spec. All injectors and fuel rail cleaned in an ultrasonic bath, and all good after that.

Hope this helps! :thumbs:

 

[BlownMotorWorks]

Thanks Philip,
Thats quite a run through . I changed the spark plugs earlier will see tommorrow morning if the problem prevails.
I know someone with diagnostics and will get all the faults cleared and battery registered and the tests done.
I did hear a knocking sound in the motor when I started up, hoping its a hydraulic lifter and not the VANOS...:nonono:
Aim is to stay positive and hope the problems solved now

:ty:
Thanks to you all so far.

 

[Philip Foglar]

Yep, best is to take one thing at a time and see what is going on.

 

[BlownMotorWorks]

[align=left]The misfire still occuring after cleaning MAF sensor and replacing spark plugs.
What I did notice,I drove off straight away after starting up and the misfire did not occur initialy as I stopped about 300 meters down the road( and I picked the rpm up high enough) and not at about 500 meters either but at about 800meters The misfire seems to start acting up as soon as the engine starts heating up and one only realy notice it when the rpm is close to idle. Could this be a faulty water thermostat or the cold start unit?

 

[Blue Shirt]

With new spark plugs, the next logical culprit is a coil pack that is causing the misfire when it heats up.

Get someone to diagnose which cylinder is misfiring, swap the coil pack on that cylinder to another cylinder, and see if the misfire follows the coil pack to the new cylinder. If so, replace the offending coil pack. Cost will be ~R800.