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First pic of my 2002 325xi

welcome aboard... the xi subforum is a very interesting place... often times very quiet but also packed with useful information. The 4wd owners seem to be more subdued than the 2wd bretheren.

nice car

Yea I've searched the forum for a while now and there's a lot of helpful information. I am having 1 issue with the car right now. I'm only getting about 16 mpg city. I've recently replaced spark plugs and vcg. No SES light on. Any suggestions of where to look next?

Originally Posted by bmw golf guy

Yea I've searched the forum for a while now and there's a lot of helpful information. I am having 1 issue with the car right now. I'm only getting about 16 mpg city. I've recently replaced spark plugs and vcg. No SES light on. Any suggestions of where to look next?

Your right foot and it's wintertime?

Winter air is denser and there is usually more ethanol in the fuel, both decreasing fuel mileage.

Your car would probably be alerting you to either a failed 02 sensor or another malfunction if something was broken and causing poor gas mileage, so if no codes then I don't suspect engine issues.

You can always scan it though... I use an ELM327 + Torque on my android for OBD2 scanning and the inpa/ediabas program I just got running for more advanced info...but that's probably not an issue

Is there black soot at your exhaust pipe exit?
Do you have a fuel leak (Puddle in morning?)

If none of those then drive it

Hmm I'll keep an eye out. I haven't noticed any black soot at the tail pipe but I haven't really looked. If there is, what would that tell me?

And definitely no gas leak

Does this tell you anything?

Don't worry about the soot, the pic looks normal and the ECU would tell you it's broken anyway.

These cars don't get great mileage (but they do accelerate nicely , try to take it easy for a couple days and see if you can get up to 20-25

Will do. Thanks for the input!

If you have more than 100k miles replace the o2 sensors ($60 each), weak sensors wil ruin performance and gas mileage.
Clean the MAF, throttle body, ICV, replace lower intake boot.
Replace the fuel filter and hoses i'd do this every 40k miles.
Get some fresh fluids for the diffs, TC, tranny, PS, brakes.
Heavy wheels don't help with gas mileage.
Keep an eye on the oil level.
Read a lot.

If either of the Intake Boots has a small crack in it, you will be sucking in unmetered air, not always setting off the SES light, but lowering gas mileage. Also, if the DISA Valve is starting to go, you may not get the SES light (will throw a couple of codes though) and gas mileage and idle and performance will suffer. The Upper O2 Sensors, if weak, can cause the SES light to come on (definitely will throw codes) and will effect gas mileage. At this point, it is best if you either purchase a scan tool and read the codes or have it done, even though the SES light isn't on. Even the Fuel Filter (which also has the Fuel Pressure Regulator as part of it) can cause poor gas mileage. You should be able to get 24 mpg in typical driving.

Ok thanks for the advice. Lately it has been having a pretty rough idle. So rough that it rattles the change in my cup holders. Thought it was the spark plugs since it still had the factory plugs with 139,000 miles on them but replacing them didn't help. I'm also leaning towards the vanos. Just not sure where to start

VANOS doesn't typically contribute to rough idle. Do you have an auto or manual?

I would start by cleaning the MAF, ICV, and checking the intake boots for rips/tears/cracks/etc. Those are the usual culprit. If you have an auto, does the rough idle reduce or go away when you put it in neutral or park? If yes, you will need new engine mounts.

Good luck.

Yea it's an auto and yes it does go away when it's put in park and neutral. How much am I looking t for new engine mounts and is this a DIY?

Get the Codes read to see if there are any stored. At 139,000 miles, it could be quite a few things that are giving you low gas mileage and rough idle, several of which have been touched on already (and they may or may not cause the Service Engine Soon light to come on). When you changed the spark plugs, did any of them have oil on them? Was there any oil on any of the spark plug coils? Any oil in the spark plug wells? If the answer to any of these questions is yes, then you well may have a spark plug(s) or coil(s) misfiring due to the oil from leaking valve cover gasket (the gaskets that seal the spark plug wells from the rest of the head). As I stated before, a DISA that is starting to go bad will produce rough idle and lower fuel mileage. Easy to check the DISA and there is a DIY video on the forum and I also believe one can be found on BavAuto's DIY site. Should not be a problem with the Vanos.

When I changed the plugs I noticed a little oil on the threads of the plugs( which lead me to replace the vcg also) nothing on the coils themselves

Originally Posted by bmw golf guy

Ok thanks for the advice. Lately it has been having a pretty rough idle. So rough that it rattles the change in my cup holders. Thought it was the spark plugs since it still had the factory plugs with 139,000 miles on them but replacing them didn't help. I'm also leaning towards the vanos. Just not sure where to start

I have been chasing this problem for 2 years now. I have replaced everything possible. The only thing I haven't replaced is the engine mounts. You will notice that as soon as the warm weather comes you will see the problem vanish.... It sucks but it seems to be a known problem with the XI's and there drivetrains. I'm pretty sure changing the mounts will not improve or fix this problem from all the information i'm gathering.

If you do manage to find out the problem or change out your engine mounts and it fixes it let me know! I'm tired of driving a 3500lb vibrator

Good Luck and Welcome!