idle stumble on start - then OK - ...UPDATE - FIXED!

Migizi · Post by **Migizi** » Fri Apr 05, 2019 9:27 pm

2006 Z4 E85 3.0si
EDIT (add)---Engine is an N52

I have done lots to this car since I purchased it in January, she is now road worthy (IMO) - including new plugs and coils, gaskets, alignment, tires, and cosmetics ...

I do however have an issue that is bothersome, perhaps someone on this forum has experienced it or knows the likely cause?....

Warm or cold...every time I start it, the idle stumbles up and down 50/75 rpm of the target idle RPM. this lasts for 5-15 seconds then settles in and all is great till next time I start it.

DISA?
VANOS?
Bueller?

Smartbear · Post by **Smartbear** » Fri Apr 05, 2019 10:44 pm

Add eccentric cam sensor to that list, you can unplug it to see if the idle becomes steady

Rob

ph001 · Post by **ph001** » Sat Apr 06, 2019 8:43 am

50 - 75rpm sounds pretty minor and if it only lasts 10 seconds or so I’m not sure I would be worrying about it. I think they all do that to some degree. I suppose you could take the vanos solenoids out and give them a good clean just because it’s easy to do but I don’t think I would be stripping eccentric shaft sensors and valvetronic motors apart at this stage.

thecookie125 · Post by **thecookie125** » Tue Apr 09, 2019 7:59 pm

Mine does this too but usually only on warm start, clears after about 10 seconds or so. Going to start by cleaning the vanos solenoids.

Jameszy · Post by **Jameszy** » Wed Apr 10, 2019 6:53 pm

Mine does this too, 3.0si, usually on a cold start. Lasts about 10 seconds. Not been an issue so far, but might consider looking at VANOS solenoids further down the line if gets worse.

Migizi · Post by **Migizi** » Thu Apr 18, 2019 5:13 pm

Although no service light, I ran diagnostics with Carly and found this...

Engine / Motor
Fault Code: 002C7E
Fault Explanation: :Lambda probe on the catalyst, trimming control

Does anyone know which one of these o2 probe/sensors is Carly referencing , I certainly don’t want to replace a good probe

Migizi · Post by **Migizi** » Sat May 25, 2019 3:54 pm

I fixed it!

Using INPA, I did a Valvtronic Adaptation reset

wonkydonkey · Post by **wonkydonkey** » Sat May 25, 2019 8:41 pm

Winner!

firebobby · Post by **firebobby** » Sun May 26, 2019 9:19 am

Who's a clever boy

kis · Post by **kis** » Tue May 28, 2019 6:32 pm

Out of interest was this anything to do with the fault code stored? (That you mentioned previously?)

Migizi · Post by **Migizi** » Mon Jun 10, 2019 10:33 pm

kis wrote: ↑Tue May 28, 2019 6:32 pm Out of interest was this anything to do with the fault code stored? (That you mentioned previously?)

not that I could tell

ph001 · Post by **ph001** » Tue Jun 11, 2019 9:46 am

Can you run through how you get to this in INPA please? Sounds like a few cars might benefit from it as time goes on.

Capa · Post by **Capa** » Tue Jun 11, 2019 11:18 am

The above would be beneficial, for sure.

Also - I see a lot of people suggesting that you can remove the eccentric position sensor whilst the car is runninig.... If you do this to mine, it dies... Is this evidence of a fault with it?

Flyingfifer · Post by **Flyingfifer** » Tue Jun 11, 2019 12:16 pm

ph001 wrote: ↑Tue Jun 11, 2019 9:46 am Can you run through how you get to this in INPA please? Sounds like a few cars might benefit from it as time goes on.

+1 I had this issue and several others had the same

Damn good work Migizi!