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Discussion Starter #1
Fairly new here and 1 month owning a pretty nice 2003 330ci convertible.

These 2 codes popped up twice now; looking for advice as to whether look towards a vacuum leak(s) or a faulty MAF sensor?

Leaning towards the MAF because both times the codes dropped during highway speed driving (never seen them while stop / start traffic or idling)

Attached the freeze frame for this 2nd instance (data the first time was similar but I neglected to take a pic)

I am fortunate in that I am the 3rd owner, and the 2nd owner (2008 - 2018) saved every single maintenance receipt. So I know that approx 4 - 5 years ago there were some vacuum hoses replaced, and also the valve cover gasket. Don't see anything to indicate that the MAF was ever worked on / replaced.

I did peek around under the hood and the current hoses look decent (and still feel supple, not brittle) and didn't see any obvious cracks or loose fittings, etc. The engine compartment seems to have been regularly cleaned / maintained. Engine idles stable whether parked or at a stoplight (tach is level, not bouncing around; no feeling of shaking or engine shuddering under the hood). Car starts right up, hot or cold start. No stumbling or stalling. Acceleration is good through every gear; no backfire / misfires either.

I did try a can of that MAF cleaner already (hey, it was only 8 bucks, so why not give it a shot?) but still dropping those 2 codes. So, i think a 'dirty' MAF can be ruled out (brand new Air Filter BTW)... so, in my mind, either the MAF is on its way out - or there is a leak somewhere? Or any other possibility that I haven't considered as the cause of these DTCs..?
 

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When it happens during high way driving, it's usually the fuel pump and filter and/or the maf. If you have no history on the fuel pump and filter, replace those
Your fuel trims are quite high though. I'd also do a smoke test to eliminate vacuum leaks https://youtu.be/AsgB9eBl58I
 

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Lean condition at higher RPM's will either be an under reporting MAF and/or a soft failing fuel pump.

The MAF's on our engines do not usually get oil fouled due to crankcase airflow. They do get contaminated with silicon which you cannot clean off. So trying to clean the MAF's on our cars is a total waste of money and time.

Suggest you read this thread for more ideas: Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616
 

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When I had those codes it was a tear in the intake boot. It doesn't look like you checked that yet.
 

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Hi what would be the cause of getting only p1074 as a pending I've gotten it pending on my car 3 separate times so far but in very long stretches of each other, I did also P0460 pending a month ago aswell, but never came back, I replaced upper intake boot before all of this, I replaced the fuel pump with a VDO pump last year around this time aswell. I do get fluctuations in my rpms but only when heat/AC is on.

Right now I'm going to rebuild my DISA valve, replace the lower intake book.

And possibly the 2 hoses that connect to the F connector if they are not too hard to replace.

But the P0460 pending code kinda concerns me.

Sent from my SM-G955U using E46Fanatics mobile app
 

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Hi what would be the cause of getting only p1074 as a pending I've gotten it pending on my car 3 separate times so far but in very long stretches of each other, I did also P0460 pending a month ago aswell, but never came back, I replaced upper intake boot before all of this, I replaced the fuel pump with a VDO pump last year around this time aswell. I do get fluctuations in my rpms but only when heat/AC is on.

Right now I'm going to rebuild my DISA valve, replace the lower intake book.

And possibly the 2 hoses that connect to the F connector if they are not too hard to replace.

But the P0460 pending code kinda concerns me.

Sent from my SM-G955U using E46Fanatics mobile app


Please start your own thread.
 

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Discussion Starter #7
Thanks for all the comments and great advice! :thanks:


I had the time to go through all the maintenance receipts that came with the car. I think these can help me narrow down the likely culprit(s) a bit more.


Here is a listing of repairs / replacements that should be relevant to this thread question (car has 128K mi currently):


- Valve cover gasket replaced 10/2012 (84K mi)

- Crankcase Vent Valve / 3 breather hoses (vac hoses?) / 2 MAF Breather Boot (Upper / Lower Boot?) / Oil Separator Hose / Fuel Pump & Sender Seal all replaced 01/2013 (87K mi)

- Power Steering Suction Hose / Return Hose / Reservior all replaced 02/2014 (97K mi)

- Spark Plugs 10/2014 (103K mi)

- Battery 05/2018 (126K mi)


There were other things fixed as well (owner spent a total of $8200 over the past 10 years; not counting routine stuff like oil changes) but I'm just listing things that MIGHT contribute to the current code problem...


Anyway, based on this info, I think this is the smartest way to proceed =

1) Replace Fuel Filter. Pump was replaced 5.5 yrs / 40K mi ago; so probably still OK. But no evidence that Fuel Filter has ever been replaced.

2) Do a smoke test and replace any leaking hoses. Even though a good amount of vac lines, etc have been changed out and are less than 6 yrs / 40K mi old... not all of them are new. Plus, looks really cool to do :excited:

3) Reset codes and see if they drop again.

4) If they drop again, replace MAF sensor.

5) If they still drop after that... well, if I have changed fuel filter AND fixed any vac leaks AND changed MAF and STILL get these codes...

6) Have a shop test the (replaced) Fuel Pump (?)


How does that plan sound???
 

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Bobc,
Posting fuel trims at idle and at 3000 rpm would be super helpful.
If they are high (like on your freeze frame) at idle then vacuum leak is likely. Check for torn boots and the disa oring first then there are a obviously other leaks to look for if not those.
If trims are high at speed, then look towards fuel pump, fuel filter/regulator (single unit on '03). Injectors should be on your radar too but since both banks are the same, that seems unlikely.
 

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Don’t waste your money on a new MAF. Get the OBDFusion app for your smartphone or tablet. Then search this forum for threads on OBDFusion in which jfoj has commented. He’s the guru. The app will let you see the operation of the MAF in real time.
 

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Lean condition at higher RPM's will either be an under reporting MAF and/or a soft failing fuel pump.

The MAF's on our engines do not usually get oil fouled due to crankcase airflow. They do get contaminated with silicon which you cannot clean off. So trying to clean the MAF's on our cars is a total waste of money and time.

Suggest you read this thread for more ideas: Solve your misfires, lean codes, rough idle - http://forum.e46fanatics.com/showthread.php?t=897616
+1 on the soft-failing fuel pump. You might as well replace it now, because you're going to have to do it anyway in the not too distant future, and if it is the problem now, you will save yourself a lot of time, money and banging your head against the wall. If it's not the problem now (and I'll bet it is), you've just eliminated a huge variable from your search and built future reliability into the car. Siemens/VDO is the only way to go - an OEM part without the dealer price. Good luck!
 

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FWIW, I stopped getting those codes when I changed a leaking OFHG and then the fuel pump. Even when I changed the pre-cat O2's I would still get the codes. I did get the light one time maybe a month or so ago on the highway but it went away by itself. That's compared to getting it every single time I took it on the highway. I still have a leaking oil pan gasket. I personally do not think that code is coming from the CCV, the MAF sensor, or a leaking intake manifold gasket.

The car actually drives a lot better after the fuel pump swap. I would start there first to be honest.
 

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Discussion Starter #15 (Edited)
Guys, got a question...

Several suggestions to start with replacing the Fuel Pump. Maybe it got overlooked, but the original Fuel Pump was already replaced about 5 yrs / 39.5 K ago... At a BMW dealer shop.

Or are you thinking that this 2nd Fuel Pump - with slightly less than 40K mi on it - is already on the way out???!!!
 

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Guys, got a question...

Several suggestions to start with replacing the Fuel Pump. Maybe it got overlooked, but the original Fuel Pump was already replaced about 5 yrs / 39.5 K ago... At a dealer shop.

Or are you thinking that this 2nd Fuel Pump - with slightly less than 40K mi on it - is already on the way out???!!!
Could've been contaminated or a cheap brand. All of these issues seem to be pointing to the fuel pump. Make sure you get a Siemens/vdo
 

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Discussion Starter #17 (Edited)
That's why I figured Fuel Filter / Regulator first... That has never been replaced as far as I can tell.

Also, no need for OFHG... Thank God I have ZERO fluid leaks
 

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I owned 3 bmws year 99 to 2006 and everytime i had those two codes it was some kind of vacuum leak, sometimes along with misfire codes. I would check all usual suspects first including intake boots, ccv lines, secondary pump lines, capped off vacuum ports on rear of intake manifold, disa valve. Then to maf sensor then fuel filter, lines, pump. In my experience this is the order from most likely to least. If it is a vacuum leak, a small leak like cracked vacuum line to secondary pump usually isnt enough to warrant a code and a lot of times it is a combination of several leaks that bring up those codes.
Hope this helps....


Sent from my iPad using E46Fanatics
 

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Guys, got a question...

Several suggestions to start with replacing the Fuel Pump. Maybe it got overlooked, but the original Fuel Pump was already replaced about 5 yrs / 39.5 K ago... At a BMW dealer shop.

Or are you thinking that this 2nd Fuel Pump - with slightly less than 40K mi on it - is already on the way out???!!!
So by not mentioning this vital piece of information, you've introduced another huge variable into the equation. As I said earlier, good luck!
 

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Discussion Starter #20 (Edited)
So by not mentioning this vital piece of information, you've introduced another huge variable into the equation. As I said earlier, good luck!
Actually... I DID mention it way back in the thread. But I guess not visible enough ;)

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Thanks for all the comments and great advice! :thanks:


I had the time to go through all the maintenance receipts that came with the car. I think these can help me narrow down the likely culprit(s) a bit more.


Here is a listing of repairs / replacements that should be relevant to this thread question (car has 128K mi currently):


- Valve cover gasket replaced 10/2012 (84K mi)

- Crankcase Vent Valve / 3 breather hoses (vac hoses?) / 2 MAF Breather Boot (Upper / Lower Boot?) / Oil Separator Hose /
Fuel Pump & Sender Seal all replaced 01/2013 (87K mi)

That's why I'm still favoring Fuel Filter / Regulator replacement first, then smoke test for vac leaks / seal leaks if found...

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