Service Engine Soon light will not go away

[fernando306]

Hello my friends,

I did the oil change yesterday and reset the oil change interval doing the key pos 1, hold S/R button until reset shows up, then hold again, then click to confirm... etc. I think that worked, as it shows "oil service" 15k.

Even resetting that, the The SUPER MASTER inconvenient "Service Engine Soon" light did not go away. Any thoughts?

 

[Chris_D]

Carly time.

 

[fernando306]

Carly time.

 

[fernando306]

Hey guys,

I have codes P0175: System too rich bank 2, and code P0172: System too rich bank 1.

Replacing the spark plugs yesterday, they were quite wet - all 6 of them. What can cause that?

 

[ph001]

What engine?

 

[fernando306]

M54 3.0i - 2004

 

[colb]

Sounds like an air leak causing it to overfuel as the sensors are probably picking up extra air in the exhaust that hasn't been measured passing through the Maf. If you can view live data on diagnostics look at the fuel trims if they are high its a good pointer to an air leak in the system. Check all rubber hoses from Maf to engine and all the plastic vaccum pipes across the engine. If you can't locate a leak get it smoke tested, that usually shows up any leaks in the system. Also check the less obvious places where leaks can develop, dip stick bottom where it enters the sump and top, O rings both ends of the dipstick. If your cam cover is plastic also give that a good look, these are known to develop cracks due to age allowing air to enter. If you fail to find air leaks then start looking at the Maf, unplug its electrical connection the car will revert to default settings, see if there is any improvement in running with it disconnected. If it runs better then suspect the Maf, replace with Oem parts, Bosch or Seimens dont buy cheap pattern parts otherwise you will end up paying twice.

 

[fernando306]

I've searched for air leaks, but everything looks tidy.
I have cleared the codes, added fuel injector cleaner, changed the spark plugs with OE genuine ones and hasn't shown up every since. It's been driving better as well. Fingers crossed!

 

[fernando306]

:?

Guess what... Problem is back. But this time I've got some good information - the fuel trims look SUPER WEIRD.
I will inspect again for vacuum leaks. In the meantime, any ideas?

OBDFusion scan: https://youtu.be/kiHXwIfMZes

 

[colb]

High fuel trims and the codes its setting indicate it is overfueling, hence wet plugs, the car thinks its running lean so is adding fuel to richen it up. This is typical of a vaccum leak you need to check all the rubber hoses and intake bellows as well as all the plastic vaccum pipes on the engine for holes or splits that are letting unmetered air into the engine. The Maf is measuring the air passing through it and tells the engine module what it has seen, the exhaust sensors measure what they are seeing go past them and they are seeing more air than the Maf has reported so thinks its running lean, hence the computer telling it to add more fuel. If you can't visually find any air leaks then a smoke test will almost certainly find it and show up with smoke escaping where it shouldn't. If you smoke test it ensure you look all over the engine that includes the cam cover and exhaust manifold before the exhaust sensors. Just noticed your Maf live data Maf didn't seem to be performing very much, try disconnecting its elerctrical plug and running the car, it will be using default settings with it disconnected, see if that improves things. If it improves then suspect the Maf, you could try cleaning it with Maf cleaner but I find that dosn't always work.

 

[fernando306]

Hey colb,

I've been wanting to do a smoke test, I have to build my smoke machine to do that. I'll do it soon!
In the meantime, I checked the MAF at different RPMs:

1020 RPM = 1.01 lb/min or 7.63 g/s
1487 RPM = 1.53 lb/min or 11.56 g/s
2058 RPM = 1.75 lb/min or 13.23 g/s
2488 RPM = 2.38 lb/min or 18 g/s
3071 RPM = 2.82 lb/min or 21.3 g/s
3546 RPM = 3.65 lb/min or 27.6 g/s
4003 RPM = 4.06 lb/min or 30.7 g/s

 

[fernando306]

Guys,

My MAF is chinese. Just saw it yesterday.
What brand MAF can I safely use? The BMW is $400 bucks, VDO is $276. Any other recommendations?

 

[Smartbear]

Guys,

My MAF is chinese. Just saw it yesterday.
What brand MAF can I safely use? The BMW is $400 bucks, VDO is $276. Any other recommendations?

How does the car run with the maf disconnected? :?
Rob

 

[Chris_D]

You can't go cheap on the MAF.
Get an OEM one, or check scrappers like I did and get a BMW original for 50 notes.

 

[Ewazix]

Guys,

My MAF is chinese. Just saw it yesterday.
What brand MAF can I safely use? The BMW is $400 bucks, VDO is $276. Any other recommendations?

How does the car run with the maf disconnected? :?
Rob

The ECU has a stock map for fuelling, if you have rough running and disconnect a suspect MAFF and it runs fine, that suggests that input signals from the knackered MAFF are the likely cause ........... or so I have read on here previously

 

[fernando306]

Car runs fine, but acceleration is lumpy and uneven. Sometimes it goes like hell, sometimes it hesitates and bucks, very unpredictable.

Fuel trims are on the negative side and sometimes check engine light shows up because it is running too rich. Injectors are fine, fuel pressure is fine.

I thought MAF would be a long shot, until I saw it yesterday that it is a damn crappy 20 dollar chinese MAF.

 

[fernando306]

Would this one be fine? Or it needs to be THE genuine MAF?

https://www.fcpeuro.com/products/bmw-mass-air-flow-sensor-13627566983#reviews

 

[Smartbear]

Guys,

My MAF is chinese. Just saw it yesterday.
What brand MAF can I safely use? The BMW is $400 bucks, VDO is $276. Any other recommendations?

How does the car run with the maf disconnected? :?
Rob

The ECU has a stock map for fuelling, if you have rough running and disconnect a suspect MAFF and it runs fine, that suggests that input signals from the knackered MAFF are the likely cause ........... or so I have read on here previously

I know this, that’s why i asked the op how it ran with the suspect maf disconnected :wink:
Rob

 

[Ewazix]

How does the car run with the maf disconnected? :?
Rob

The ECU has a stock map for fuelling, if you have rough running and disconnect a suspect MAFF and it runs fine, that suggests that input signals from the knackered MAFF are the likely cause ........... or so I have read on here previously

I know this, that’s why i asked the op how it ran with the suspect maf disconnected :wink:
Rob

Ahhh "how (well) does it run disconnected", rather than "how does it run when disconnected" (as in how is it able to)

 

[fernando306]

My friends, I ordered a new MAF from FCP Euro. It's a VDO MAF. We'll see! :?
I totally forgot to try running it without the MAF.