Cold start rough idling (10 secs) and CEL codes now

[koolkat1973]

I am having this issue with my 2008 E70 X5 (N52 engine). My main issue has been the Cold Start rough idling issue I've been experiencing for the past couple of months. Recently - I've decided to tackle the problem by throwing various replacement parts at it (Intake Vanos Solenoid, Exhause Vanos Solenoid, MAF Sensor). These parts are BMW parts just to be on the safe side. They did not fix the issue with the cold start. I also plan on the doing a leak check tonight to verify that there are no leaks.

This morning, I received the following CEL lights after drving the car for several miles (P116E, P0171, P0174) so I decided to capture that Diagnostic Report per OBD Fusion App. I have attached it to this post in hope that someone can review and help me troubleshoot the issue. Thank you.

BMW_X5_Diagnostic Report 2019-05-01.pdf

[Viktimize]

Originally Posted by koolkat1973

I am having this issue with my 2008 E70 X5 (N52 engine). My main issue has been the Cold Start rough idling issue I've been experiencing for the past couple of months. Recently - I've decided to tackle the problem by throwing various replacement parts at it (Intake Vanos Solenoid, Exhause Vanos Solenoid, MAF Sensor). These parts are BMW parts just to be on the safe side. They did not fix the issue with the cold start. I also plan on the doing a leak check tonight to verify that there are no leaks.

This morning, I received the following CEL lights after drving the car for several miles (P116E, P0171, P0174) so I decided to capture that Diagnostic Report per OBD Fusion App. I have attached it to this post in hope that someone can review and help me troubleshoot the issue. Thank you.

Attachment 76045

Common cause is eccentric shaft/valvetronic. I'll have to look at your diagnostic report later though.

EDIT- I see you have lean codes. I would start with a smoke test to check for vaccum leaks

[koolkat1973]

I find that if I disconnect the MAF Sensor, then the car idle just fine on startup. Hence, I replaced the MAF Sensor thinking that the original one was bad.

[ard]

Originally Posted by koolkat1973

I find that if I disconnect the MAF Sensor, then the car idle just fine on startup. Hence, I replaced the MAF Sensor thinking that the original one was bad.

NO!


Your car is running lean, almost certainly an intake leak. Just find the leak. A smoke test will probably not tell you, it is very hard to get a good diagnstc when you have a small cracked elbow under something...


When the car starts, and youve disconnected the MAF, the DME automatically uses a default air/fuel map that is PURPOSEFULLY very rich, to protect the motor. In your case this rich map works fine with your air leak.


Start taking things apart, look for cracked pipes, plastic bits, etc

[koolkat1973]

Thank you very much for the suggestion. What I can't seem to understand is why the car runs absolutely fine after the initial 5-10 seconds of rough idle at startup. If there's a leak, shouldn't I be experiencing performance issue throughout?

[ard]

During start up the DME is ignoring the O2 sensors, it is just using a pre-set map.


If you monitor the DME, you should be ab,e to see when it is in OL vs CL (open loop closed loop). Id expect it is fine in OL, then switches to closed ...fuel trims rise, runs rough


All preset maps are rich- to protect the motor from lean/detonation.

[Baby Unicorn Taco]

Originally Posted by ard

NO!


Your car is running lean, almost certainly an intake leak. Just find the leak. A smoke test will probably not tell you, it is very hard to get a good diagnstc when you have a small cracked elbow under something...


When the car starts, and youve disconnected the MAF, the DME automatically uses a default air/fuel map that is PURPOSEFULLY very rich, to protect the motor. In your case this rich map works fine with your air leak.


Start taking things apart, look for cracked pipes, plastic bits, etc

Listen to this advice. It might be worth a one hour diagnosis at an Indy shop with a smoke test if you can’t find it.


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[koolkat1973]

Just to update my issue with the rough idling (10 seconds) at startup and then eventually engine would no longer start. After numerous attempt to start unsucessfully, I started having a no crank issue on top of the engine not starting. For the no crank, it turned out to be the Starter. I replaced the starter and it fixed the no crank issue. The rough idling issue and eventually engine not starting at all was with a defective fuel pump (passenger side). I replaced the fuel pump and the Voila... engine started and no more rough idling. I did go through several troubleshooting scenario before confirming a dead starter and a dead fuel pump. Hope this will help anyone with similar problems.

[Baby Unicorn Taco]

Any chance the fuel pump was covered under a recall for your X5? My 08 4.8i was covered under a recall. Some 6 cylinders were as well. Yours may have been. Worth checking.


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[koolkat1973]

Originally Posted by Unicorn

Any chance the fuel pump was covered under a recall for your X5? My 08 4.8i was covered under a recall. Some 6 cylinders were as well. Yours may have been. Worth checking.


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The fuel pump recall was performed on my car at 32K miles back in 2011. My car now have 123K miles on the odometer. Not sure they will cover it again. Thanks for the suggestion tho.