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Discussion Starter · #1 ·
I have an '01 325i,My problem is occasionally when I accelerate the motor flattens out for 2-3 seconds, and then takes off like a rocket. I'm not sure whether this is a fuel problem or a sensor problem. Any help would be appreciated.
 

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Maybe the o2 sensor need to be changed? How many miles on the car? Also does the car need to be "hot" before you can drive with it because if it's not the engine shut down? You have a check engine light? The more details you can give the more help you can get. :)
 

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Have you had the codes scanned ? If not, that would be the appropriate place to start....
 

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Discussion Starter · #4 ·
I have checked and there are no codes. The car has 130,000 miles on it and drives great, it decides on it's own when to hesitate. It could be on the freeway or at a stoplight. It will do it once and then drive fine.
 

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Define "occasionally". Once a day? A couple times a week? A few times per month? Also, is it getting worse as in more frequently or longer since the first time it occurred?

Have you ever changed the fuel filter? With no codes I'm guessing it's something fuel related, pump or filter.
 

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Discussion Starter · #6 ·
This has happened 3 times in the last 10 days. I've noticed that it could be only when the fuel tank is below1/4 tank. I put a can of techron in last week and it ran good until last night when the fuel was low.
 

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This has happened 3 times in the last 10 days. I've noticed that it could be only when the fuel tank is below1/4 tank. I put a can of techron in last week and it ran good until last night when the fuel was low.
If the fuel filter was never changed, it`s now 10+ years old, and probably full of crud....it needs to be done *anyway*, so this might be a good time.
 

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I would get the fuel filter changed first and then monitor the fuel trims in close loop with a code scanner. Look to see if the short term fuel trims(STFT) change wildly or not. Also look for slow responding oxygen sensors by monitoring the samething.
 
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