Engine Hesitates

[SureShot434]

So recently I have been having issues with my 2001 325i. It only has this issue when it is cold (i.e 20's and 30's, although it did it today at 58 degrees). Once the engine warms up to normal temps, the problem goes away.

Well when driving along in 3rd gear at 25 miles an hour the car sputters and hesitates almost like its going to die. It does it in ever gear until the car is at normal temps. My check engine light is on because one of my 02 sensors is bad and needs replaced. It seems like the issue is getting worse and worse, and it's my DD.

Could it be the 02 sensors, or what else could it possibly be?

[Oli77]

Don't know but I thought O2 sensors where responsible for mixing only when engine was hot. Could that be DISA?

[Johnmadd]

Don't know but I thought O2 sensors where responsible for mixing only when engine was hot. Could that be DISA?

+1 on o2 sensors only after wamup period.

Do you run your gas tank until almost empty and then fill up?

[SureShot434]

+1 on o2 sensors only after wamup period.

Do you run your gas tank until almost empty and then fill up?

Durring the summer I tend to run it almost empty, but durring the winter i try to keep at least 1/4 tank at all times.

[az3579]

1/4 tank isn't enough, IMO. That is because when it says 1/4 of a tank, it's really more like 1/8 of a tank because the gauge reads horribly wrong once it drops below an indicated 5/8 of a tank or so (note the fuel amount indicated drops significantly faster once it reaches that point). Running it empty all the time is bad for the fuel pump. It makes it work much harder and in the summer can overheat. Heat is one of the fiercest enemies for electronics.
I'm not saying that is the cause of your issue though, just an FYI.

[danewilson77]

Truth. I don't get as many miles in that last 1/4....then I do from the rest of the tank for sure.

[Johnmadd]

Other than working the pump harder, moisture can build up with the changing temps and condensation can build up inside of the tank which is ultimately water in your gas and if you do this enough the tank will get rust inside eventually. I don't think you have rust but maybe moisture, I would run some stabilizer or seafoam through the gas at your next fill up and see if that helps.

[llll1l1ll]

I was going to say it sounds like your fuel pump is on the way out, but it only does it when your car is cold.

Perhaps the fuel pump also needs time to warm up?

[Hermes]

I'm willing to bet 95% on fuel pump, 5% on your battery and/or coils on their way out but not throwing codes yet