330i Strange engine condition - no power

I've searched around and found a few things, but nothing seems to really match up with my exact issue. I have a 2002 330i with 111,000mi. I've owned the car for 2 years with no issues beyond an expansion tank, which I replaced myself a year ago.

On the way home from work last week, the engine took about one turn longer than normal to start (maybe an extra half second on the starter). Then the full way home, the engine had NO power at all. As in, it would take nearly 50% throttle just to engage the clutch from a stop without stalling. The engine otherwise ran fine - idle was normal and smooth. It was just extremely weak and accelerated very slowly. Once, on the 3-4 shift, the rpms just fell like a rock and it stalled. I simply left the clutch in and it restarted immediately.

Once I got it home, I turned it off and inspected everything I could think of, looking for a vacuum leak or something of that nature. I didn't find anything, so I restarted the car (it had been sitting about 30mins) and it was absolutely fine. Back to full power, no issues.

A couple days later, it acted exactly the same way - very weak - but once again was fine after I shut it off for about 3mins. Otherwise the car has been fine since, driving just as normal for several days now.

Any ideas? The car is not throwing any codes. Thanks.
Edit: I should say, the car is not throwing an SES. I have not checked for codes since there isn't an SES.

There are a plethora of codes that don't throw the SES on. So you should still check. I can't help anymore than that, someone else will pick it up from here.

Dirty mass air flow sensor? just a guess.

Very out there idea, but maybe the sensor for the drive by wire on your throttle is acting up. Try the DIY throttle reset and see if it helps.

It may sound weird but it may be your fuel pump as well.

^word... I had those symptoms when my pump went out.

OP,

First, xl50

Could be fuel pump...if you haven't changed fuel filter in the 2 years you've had it, I bet it hadn't been changed 4 years prior to that.

You could be low on gas--don't trust gauge.

And then, on the air side, could be a leak...and the lower intake boot is the one I bet you didn't check as it takes an xl50 and inspection mirror...or getting down there...which you'll have to some day anyway!

This is a major air leak if it's one.

The maf should be cleaned as should air filter (since it sounds like you only did ET...not sure if other basic stuff is up to speed).

If you can start it, drive it to Autozone, or just plan on doing lots of stuff randomly. I think you'll find a lean code, but don't get talked into buying O2 sensors from Autozone guy just yet!

HTH

Doug

I'm thinking it's got to be something electrically-related. IE, if it were an air leak (or vacuum leak), you'd think that condition would persist consistently, as the hole isn't going to plug itself and the conditions were identical before/after the issue.

Fuel pump seems odd though. Don't those typically either work or not work? Even assuming it was only achieving partial flow for those days I had the issue... now it's back to full power? Seems a bit unusual for a fuel pump. But I'm no expert.

Thanks a million for the ideas so far. Any other suggestions? I'm taking the car to a stealer (there are literally no indy shops remotely near me) later this week. I'd like to give them some idea of where to start looking... otherwise their bills tend to go up exponentially.

Originally Posted by BtheD19

I'm thinking it's got to be something electrically-related. IE, if it were an air leak (or vacuum leak), you'd think that condition would persist consistently, as the hole isn't going to plug itself and the conditions were identical before/after the issue.

No, quite often air leaks get worse as car warms up or are being pushed...the suction/heat will cause them to start whistling/whining or as in a case like maybe you have, open up so much that the car gets seriously messed up...combined with clogged fuel filter, wouldn't surprise me if it stalled...add in a dirty icv, dirty TB, it would surprise me less.

Fuel pump seems odd though. Don't those typically either work or not work? Even assuming it was only achieving partial flow for those days I had the issue... now it's back to full power? Seems a bit unusual for a fuel pump. But I'm no expert.

Fuel pumps often seem to have been giving hints before...but what's your fuel situation...ditto fuel filter.

Thanks a million for the ideas so far. Any other suggestions? I'm taking the car to a stealer (there are literally no indy shops remotely near me) later this week. I'd like to give them some idea of where to start looking... otherwise their bills tend to go up exponentially.

You know, you could buy the tools you needed and read stuff and fix this yourself. Fuel pump is 15 mins. for the guys who brag...which mean 1/2 for moron...if he's spent about 2 hours studying here. Tools? For $100 you're fixing lots of stuff...just saying.

You play with legos as a kid? Same as that!