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Hello All,

BMW 323CI SE Coupe - E46 - M52 - 1999 - 37K Miles

Need a bit of advice on tracking down an air leak on this 1999 323 I have just purchased. Or any other suggestions on what could be the cause of the symptoms?

The car idles at a steady 750 rpm after having a bit of rumble and cough when starting from cold. The misfire is felt mostly at idle, when pulling away in first then changing up to 2nd but it cruises quite steadily in 4th & 5th. The car feels like it could be a bit faster accelerating, but not in limp/safe mode. It doesn't stall or cut out.

I have changed the oil/oil filter. Air filter. Cleaned the MAF with electrical cleaner. checked over some pipes they seem to be in good condition, but I could easily have missed something. Hoping to replace all spark plugs, clean throttle body and clean idle control valve soon, so may come across a split pipe that I haven't got to yet.

Codes p0170 p0173 p1250 all point to a vacuum leak I believe. But p1250 is a code I have not encountered before on a car so is this relating to a fuel filter problem separately from the possible air leak??
The fuel trim bank 1 is reading a steady 2.3% and the fuel trim bank 2 is reading 10% which im aware is high (set the Engine Light on) so is the vacuum leak possibly at the spark plugs or something like this?

All read through OBD II + Full Torque App for Android.

I have included 2 images. 1. Is the screen shot of the codes 2. is the reading from the long term fuel trims.
I have read from past posts that the short term trims are not required when diagnosing a problem like this as they're constantly reacting and updating to the environment and load.

Wondering if anyone could give me an indication of key areas to look for concerning vacuum leaks and where they may have had an vacuum leak also.

If I have missed any key information apologies but I will edit and add as required.

Thanks

Tomo

Screenshot_20170909-103947.jpg Screenshot_20170916-133448.jpg
 

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Best to check the intake hoses from the MAF down to the engine. If they haven't been changed on your car, they are most likely to be a cause of vacuum leaks and rough idle etc. It might be hard to see any splits on the hoses as they are ribbed, but check anyway. I have the same car and changing both intake hoses solved the rough idle. Good to change the plugs as well cleaning the throttle body and ICV.
 
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