3.0Si (N52) suspected MAF - rough idle/slow pick up (not loving Carly...)

[Newbers]

I've been Googling but not really located anything exactly relevant...

I've had the engine light on for a while without any obvious symptoms. I did borrow an ODB reader and it gave a 'running lean code' (sorry don't have exact codes here).

I did suspect more recently that the pick up was a bit slow (heel and toe having to be a bit heavy footed to get revs up). Just before Christmas someone disconnected the MAF and I got the impression that it perhaps picked up better but it wasn't very obvious.

Just this week it has now started (intermittently) to struggle to idle (revs all over the place, below normal idle speed and has actually cut out).

Would you be comfortable based on that description of symptoms to replace the MAF? I don't want to unnecessarily swap parts that are OK but if I can pick one up cheap and change it quickly that will be less hassle than getting it booked in and probably not a lot dearer...

Car (Coupe 3.0Si - N52) has done 70,000. Couldn't see any signs of splits. Does have a leaky rocker cover gasket but I don't think any of that oil gets anywhere near the air intake.

 

[GuidoK]

Running lean.....cheap MAF....leaky rocker cover gasket....No obd2 code written down...
Where do I begin :roll: .....

First of all I would steer clear of any 'cheap' MAF. They are rubbish. Hit&miss.
I also wouldnt change the MAF on a lean code. Could just as well be the o2 sensors, or a vacuum leak.
Fixing a car begins with a proper diagnose in my book. Swapping out parts randomly gets expensive really really fast.

Diagnosing a MAF includes at the least monitoring the data on how much air it measures and monitoring the fuel trims

 

[derin100]

Fixing a car begins with a proper diagnose in my book. Swapping out parts randomly gets expensive really really fast.

Ain't that the truth! Don't do it.

I used to have this mechanic who was the worst diagnostian ever! He'd ignore the 'computer' even when it was correct in telling him EXACTLY what was wrong! Trusting in himself....and to my bloody expense...by ignoring exactly Guido's advice.

Don't "guess" on these cars.

 

[bradz]

Find out the exact fault code.

Could be anything from and air leak to vanos issues.

If you fancy a drive to Bedford I'm happy to plug it in for a beer 8)

 

[Chris1981]

I think it has already been summed up nicely by others but the random replacement of parts is not a good idea... certainly do not buy a cheap or 2nd had MAF!

You need to get the codes read, there's a thread on the forum which lists members with Carly so you should be able to find someone that will read the code for you!

https://z4-forum.com/forum/viewtopic.php?f=2&t=97818&hilit=carly

Cleaning your current MAF could be a good start, MAF cleaner won't cost more than a £10 from any branch of halfords, if you take it out and have a good look at the wire you'll see whether it's dirty or not, mine was filthy and cleaning it helped with a very occasional erratic idle... but i never had an engine light. I suspect TPS for mine as the erratic idle comes in after very light throttle and goes when I give it a good rev!

If the erratic idle disappears when the MAF is unplugged then it's definitely a contributing factor, but the 'Lean Mixture' code you pulled does point more towards O2 sensor or un-metered air getting in somehow, the CCV system vents into the inlet manifold which could have a potential leak if you're happy the rest of the air intake is intact!? Or potentially an issue with fuel delivery??

 

[GuidoK]

Cleaning your current MAF could be a good start,

Cleaning your MAF isnt without its risks though.
In essence, if your MAF is dirty, you have another problem. The air filter should remove ALL dirt from the air.
If your MAF is dirty, somehow dirt got past it. That can happen for example if your filter got wet, or if you use an aftermarket reusable filter (oil based).

With 70k miles the MAF should be absolutely clean and working (maybe if you got double that mileage it would be different).

 

[ph001]

O2 sensor was replaced on my 3.0Si at about 60k miles so they do fail. If was before I bought the car though so can’t tell you the symptoms but they are certainly known to cause a rough and erratic idle. That would certainly be right at the top of my suspect list. Code should confirm.

 

[Newbers]

Thanks for all thoughts above. I bought an ODB2 reader earlier so hopefully early next week I should be able to come back and reset the starting point.....

 

[Chris1981]

Thanks for all thoughts above. I bought an ODB2 reader earlier so hopefully early next week I should be able to come back and reset the starting point.....

Did you manage to get to the root cause of the this one yet newbers? any luck with codes? My very occasional erratic idle shows nothing on Carly

 

[Newbers]

Did you manage to get to the root cause of the this one yet newbers? any luck with codes? My very occasional erratic idle shows nothing on Carly

Are you using the paid for Carly app Chris1981? - Against my better judgement I bought a cheap ODB2 bluetooth reader which it turned out didn't work so I have now committed to buying a Carly adapter (and I guess the advanced app).

The plan was to then post up details of the fuel trims and error codes etc. and hope that I could get a bit more help.

I've recently moved my garage and home office which has been pretty disruptive hence the missing notepad with the error codes in and sense of disarray that I have presented here...

I've looked carefully and all of the plastics/rubbers on the inlet side are in good condition so I don't believe there are any leaks. The leaky rocker cover gasket is pretty minor and a distraction in this case. Also air filter is standard and recently replaced (I will check its clean/dry tho.)

I've previously replaced O2 sensors and they gave different errors (and as I recall no obvious symptoms).

It's getting to the point where this car is becoming nearly as irritating as it is enjoyable and I keep finding myself looking more closely at 911's and bizarrely Panamera's......

 

[ph001]

Hmmm if you have replaced O2 sensors recently and eliminated the MAF, it could be the DISA valves (there are 2). The one under the intake manifold is a bitch to get to. The N52 is pretty good usually.

 

[Chris1981]

Yeah I'm using the full version, the lite version is no use at all!

Carly is reasonably good for fault finding and for coding, I've used it to diagnose a couple of issues but there is no live data functionality on the N52 engine which is incredibly annoying as that was the main reason for purchasing the app and connector! If you were wanting to monitor fuel trims, air flow, etc you might struggle with Carly.

I hadn't ever suspected DISA valve being an issue on idle but given they alter airflow it's a possibility! ph001 is right, the smaller DISA valve under the inlet is a complete pain to get at so best be sure that's the culprit before tackling it!

Good luck getting to the bottom of it, keep us posted if you find anything out!

 

[jamie_z4]

sounds like the eccentric shaft sensor, my coupe failed and had the same symptoms. very common on the n52- surprised no ones mentioned it yet.
http://www.e90post.com/forums/showthread.php?t=697252

 

[Chris1981]

I looked into eccentric shaft sensor a while back, think I may have read that very thread!

I've not had performance issues highlighted in the e90 post, just a very occasional lumpy idle and no oil leak into the plug.... but a good shout all the same and costs nothing to check for oil in the connector.

Worth looking [ref]Newbers[/ref]... eccentric camshaft sensor is at the front of the engine under the plastic cover if you didn't already know.

Given the scale of job to change it hopefully that's not the case, I certainly wouldn't be changing it unless I was 100% sure it's the reason!

 

[Smartbear]

I looked into eccentric shaft sensor a while back, think I may have read that very thread!

I've not had performance issues highlighted in the e90 post, just a very occasional lumpy idle and no oil leak into the plug.... but a good shout all the same and costs nothing to check for oil in the connector.

Worth looking [ref]Newbers[/ref]... eccentric camshaft sensor is at the front of the engine under the plastic cover if you didn't already know.

Given the scale of job to change it hopefully that's not the case, I certainly wouldn't be changing it unless I was 100% sure it's the reason!

You can unplug the sensor to see if the idle steadies out, if it does the sensor is fubard
they cost a bomb from bmw but I remember stupot from here managed to source his from Germany by cross referencing the serial number & got it for half price
Rob

 

[jamie_z4]

Maf is very rarely the case with these cars.

The amount of forum diagnosing over the years I've seen 'its the MAF' mate is frightening. The maf rarely fails, the most likely suspect is the cam sensor, eccentric shaft sensor or an air leak. All pretty common on the n52.

 

[Chris1981]

Can the eccentric camshaft sensor go without there being an oil leak into it? I simply assumed that no oil leak or poor performance meant it was ok!?

Good shout though Jamie, camshaft sensor could well be the issue Newbers is facing if he has a slow pick up too... the Vanos system won't be functioning correctly so power will be affected, this was the case in my M3 when the inlet cam sensor went! But gave me n error code so was easy to pinpoint!

 

[jamie_z4]

Can the eccentric camshaft sensor go without there being an oil leak into it? I simply assumed that no oil leak or poor performance meant it was ok!?

Good shout though Jamie, camshaft sensor could well be the issue Newbers is facing if he has a slow pick up too... the Vanos system won't be functioning correctly so power will be affected, this was the case in my M3 when the inlet cam sensor went! But gave me n error code so was easy to pinpoint!

the cam sensors are common on most BM engines to be honest mate, very subject to rapid heating and cooling being in the block

the Eccentric shaft sensor the seal usually fails from the cam cover which means a dead sensor, but as you say, if its dry, its unlikely its failed.

 

[Newbers]

I must confess I didn't know I even had an eccentric camshaft sensor.

At the moment the car is stuck in the garden blocked in by a skip and about 10 tonnes of hardcore, hopefully a few of these jobs will get sorted this weekend....

 

[Tomsdad]

For what it's worth I have the same car same engine and it had the same symposium and same errors
Check the long thread under my name.
Turned out to be the vanos solenoids. A ZERO COST AND VERY QUICK FIX. Just remove and clean them.
Always do the cheap fixes first before buying parts.