I Should Be Able Fix This Problem!! BUT I CAN'T FIGURE IT OUT!!

Allright, I've read through a whole lot of threads to try and figure out what's going on with my 325. It's actually pretty sad to read how many similar problems we all have, can you imaginge how much money the dealer's are making on the many thousands of people who blindly take them in for repairs?

Most of those problems cost either money or time, that's a given. But I am totally frustrated that I haven't been able to figure out why my car keeps sputtering.

The car runs fine while cold for about 3 or 4 minutes, and then it starts to sputter at an idle and won't run without being revved. On the road it sputters throughout the rpms and occasionally cleans out and runs smooth.

It codes with rich mixture, lean mixture and misfires in specific cylinders. It doesn't smoke or burn oil. There's no water in the oil. The plugs seem to be burning clean.

After reading the threads, here's what I've done....

6 new coils, connectors, and plugs.... still sputters.
Searched for vacuum leaks.... couldn't find any, none obvious.
New Mass Air Sensor..... still sputters.

But when I disconnect the MAS the car runs great (even though the MAS is new)

Could it be......?

A bad Idle Control Valve screwing up the MAS readings?
The compueter needs to be reflashed so it knows there's a new MAS?
The computer needs to be reprogrammed because it's screwed up?


Any Suggestions?

O2 sensors?

i was thinking O2 sensors as well.

i am having the same problem been driving me crazy. i have also replaced coils, intake boots, spark plugs and boots, fuel filter, battery, ccv which helped for a week then started doing the same thing. so now my car is at the dealership because i gave up on it and decided to let them deal with it even though its gonna cost me

Is there a way to test the O2 sensors before replacing?

ou330ci, Did you get a final verdict from the dealer? What did they diagnose?

02 Sensors here as well.

Search and you will find a thread where someone got them for i think 60 dollars. good luck you need 4.

what octane fuel do you usually put in the car? I've heard people really screw their motors up by just putting regular in. Just a thought.

As above, o2 sensors or blocked/jammed injectors. Possibly injectors as you say when you rev it hard, it runs ok. Give it a hard run, lots of revs and see if it cleans out, otherwise o2

Adjuster unit
ICV

Clean them both and see if that helps. Replace if they, either or both look funky, like their not working properly. Be careful of the adjuster, it has a nut that can break off and fall into your cylinder.

#1 clean out the ICV with carb cleaner.

#2 take out the Adj. unit and clean then re-instal with high temp gasket maker.

#3 put in a high consintration of injector cleaner (lubro moly) into gas tank and run the car hard down the highway for a while.

If none of that works take it into the dealer. Otherwise you could spend endless $$ trying to figure out what the REAL problem is.

Have you done any work to the car before you started having these problems?

I had a similar problem. Changed the oil, topped off the coolant, changed the spark plugs and the fuel filter. Now she runs like a top. I would change the fuel filter if you haven't recently.

Good luck.

EDIT - I see you changed the fuel filter. Reading is Fundamental. My bad!

Thanks all for your suggestions. A key thing to me is that it runs great when the MAS is disonnected. Would that tie to the O2 sensors, the ICV, the adjuster unit??

that would tie to the O2 sensors most likely. Have you messed with them at all lately? Maybe switched the connections? How new is your air filter? How new is your MAF sensor? Maybe it should be cleaned with some CRC MAF sensor cleaner.

Have you checked the rubber hose that runs under the plastic cover at the top of the engine (I've heard it referred to as a "balance" pipe, you'll have to remove plastic cover to see it).

Earlier revisions particularly I've heard can deteriorate and leak, the later revised part has a kind of "insulated sleeve" adding extra protection from long term exposure to the extreme temperature changes at the top of the engine.

Check all your rubber hoes im telling you you will NOT find any cracks and tears unless you LOOK deep for them, if you bend the curves and grooves on the hoes you will be able to see cracks that you wouldnt be able to see unless you really look in them... If you pull the codes and have a bad O2 sensor it should tell you if its before or after the cat, and bank 1 or 2, your car has 4... but all those codes dont mean ****, it could all be caused by ONE problem... good luck

check air intake boot that goes to throttle body for cracks, that was the problem on mine

gotta be sensors, had this problem with my 328i and now its fixed

Wouldn't the computer show a specific code for bad O2 sensors?