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Uneven idle

mcbutler
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Uneven idle

Post by mcbutler » Mon Oct 30, 2017 9:53 am

Hi All,

Might be nothing but over the past few weeks I have noticed that occasionally the idle on my car will rise from 500rpm to around 900rpm momentarily, literally just a gentle 'rev up' and back to idle. Never happens when its warm though.
Car is a 2009 23i with nearly 80k on the clock, full history, drives like a dream..

Any ideas chaps??
Mark
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ph001
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Uneven idle

Post by ph001 » Mon Oct 30, 2017 10:03 am

Does this just happen first thing from cold after leaving overnight?
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mcbutler
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Uneven idle

Post by mcbutler » Mon Oct 30, 2017 8:29 pm

It happens irregularly, up until the oil has reached 70 deg then it behaves itself. It does not do it every time it idles and not more than twice on each idle.
If all that makes sense?
I am thinking injectors....
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Uneven idle

Post by ph001 » Tue Oct 31, 2017 12:46 am

Hmmm, maybe but it's not classic injector symptoms. It's perhaps worth having a little spray around the engine with damp start to see if the revs rise to eliminate an air leak somewhere.

Maybe someone else with a 23i could comment if they ever get the same? I have known other cars do this to a lesser degree when the engine is loaded with things like the air con compressor kicking in.
Last edited by ph001 on Tue Oct 31, 2017 8:07 am, edited 1 time in total.
2007 E85 Z4 3.0Si manual :driving:
19" CSL's | Eibach Springs | Aeroskirts | Z4M front bumper | Clear brake light | ZHP | RCH+| Stubby

2004 E46 M3 coupe manual - gone but not forgotten.

Image

EssexZed

Uneven idle

Post by EssexZed » Tue Oct 31, 2017 12:55 am

I don’t have the answer but the 23i I had displayed exactly the same symptoms. It was still the same when I traded it in last year. I did report it to the local BMW dealer when taking it to be serviced but they said they couldn’t find anything wrong with it.

mcbutler
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Uneven idle

Post by mcbutler » Wed Nov 01, 2017 10:33 am

ph001 wrote: Tue Oct 31, 2017 12:46 am Hmmm, maybe but it's not classic injector symptoms. It's perhaps worth having a little spray around the engine with damp start to see if the revs rise to eliminate an air leak somewhere.

Maybe someone else with a 23i could comment if they ever get the same? I have known other cars do this to a lesser degree when the engine is loaded with things like the air con compressor kicking in.
I rarely use the AC, last long trip I picked a long flat straight, set the instantaneous mpg display and watched the mpg as i switched it on and off. 10 MPG DIFFERENCE!!!!!!, that is over 35% less mpg or another £40 on my fuel bill for the trip each way!!!!
Mark
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mcbutler
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Uneven idle

Post by mcbutler » Wed Nov 01, 2017 11:32 am

OK, got a fault code this morning, read from Carly is the following;

Note the mileages, second fault is the one that triggered todays yellow light.
Had a slight ticking in the head at times when cold as well, any ideas chaps??

Faultcode: (0x2A98) Crankshaft - inlet camshaft, correlation
Faultset 1:
(appeared at: 126048.0km)
(Engine) - oil temperature:
33.00 °C
engine status:
3.00 0-n
Engine speed:
1280.00 rpm
Voltage cl. 87:
14.73 V

Faultcode: (0x2A82) Intake Vanos variable cam control test
Faultset 1:
(appeared at: 128240.0km)
Engine speed:
1760.00 rpm
engine temperature:
89.25 °C
camshaft intake:
66.75 °CRK
Camshaft intake setpoint:
60.00 °CRK
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Uneven idle

Post by ph001 » Wed Nov 01, 2017 12:59 pm

Well from that you would have to suspect either camshaft position sensor or a Vanos issue (probably solenoid). Neither are particularly expensive or difficult to replace on the N52B25 engine. Ducklakeview is your man for Vanos work at sensible money.

Crank case breather valve has been known to cause strange issues as well.. https://www.youtube.com/watch?v=cIRPtA93wxw
Last edited by ph001 on Wed Nov 01, 2017 1:12 pm, edited 2 times in total.
2007 E85 Z4 3.0Si manual :driving:
19" CSL's | Eibach Springs | Aeroskirts | Z4M front bumper | Clear brake light | ZHP | RCH+| Stubby

2004 E46 M3 coupe manual - gone but not forgotten.

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Uneven idle

Post by Ducklakeview » Wed Nov 01, 2017 1:02 pm

Yup, looks like a lack of correlation between "requested" intake cam position and "actual" which could be caused by the solenoid not opening/closing correctly.. It's possible to "test" the actuations more thoroughly on my Launch, whereas Carly just gives yo the codes.

Mike

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Post by ph001 » Wed Nov 01, 2017 1:15 pm

This little guide looks useful for the cam position sensor, but I suspect vanos solenoid is more likely.... http://www.pelicanparts.com/BMW/techart ... lacing.htm
2007 E85 Z4 3.0Si manual :driving:
19" CSL's | Eibach Springs | Aeroskirts | Z4M front bumper | Clear brake light | ZHP | RCH+| Stubby

2004 E46 M3 coupe manual - gone but not forgotten.

Image

mcbutler
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Uneven idle

Post by mcbutler » Wed Nov 01, 2017 3:07 pm

Ducklakeview wrote: Wed Nov 01, 2017 1:02 pm Yup, looks like a lack of correlation between "requested" intake cam position and "actual" which could be caused by the solenoid not opening/closing correctly.. It's possible to "test" the actuations more thoroughly on my Launch, whereas Carly just gives yo the codes.

Mike
Hi Mike, What is 'my launch?'..
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Uneven idle

Post by Ducklakeview » Wed Nov 01, 2017 3:16 pm

mcbutler wrote: Wed Nov 01, 2017 3:07 pm
Ducklakeview wrote: Wed Nov 01, 2017 1:02 pm Yup, looks like a lack of correlation between "requested" intake cam position and "actual" which could be caused by the solenoid not opening/closing correctly.. It's possible to "test" the actuations more thoroughly on my Launch, whereas Carly just gives yo the codes.

Mike
Hi Mike, What is 'my launch?'..


That..

Mike

mcbutler
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Uneven idle

Post by mcbutler » Wed Nov 01, 2017 3:18 pm

Ducklakeview wrote: Wed Nov 01, 2017 3:16 pm
mcbutler wrote: Wed Nov 01, 2017 3:07 pm
Ducklakeview wrote: Wed Nov 01, 2017 1:02 pm Yup, looks like a lack of correlation between "requested" intake cam position and "actual" which could be caused by the solenoid not opening/closing correctly.. It's possible to "test" the actuations more thoroughly on my Launch, whereas Carly just gives yo the codes.

Mike
Hi Mike, What is 'my launch?'..


That..

Mike
Ah HAH, a bit out of my price range me thinks..

I am taking it to a local indy next friday, I have a warranty direct cover on it, lets see how they take the news.... Badly I am thinking.
Later today I will do the crank breather test, see how hard its 'sucking'....

Thanks for your help.
Mark
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35i
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Black leather

mcbutler
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Uneven idle

Post by mcbutler » Thu Nov 02, 2017 6:08 pm

Not the breather, no vaccum at all in the crankcase.
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Uneven idle

Post by ph001 » Thu Nov 02, 2017 6:36 pm

The two Vanos solenoids are simple enough to whip out and give a good clean through with carb cleaner. Access is a bit tighter on the Z4 than on other N52 engines but doable.... http://www.zpost.com/forums/showthread.php?t=1022260

and this...
viewtopic.php?t=84789
2007 E85 Z4 3.0Si manual :driving:
19" CSL's | Eibach Springs | Aeroskirts | Z4M front bumper | Clear brake light | ZHP | RCH+| Stubby

2004 E46 M3 coupe manual - gone but not forgotten.

Image

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