X5 4.6 V8 Running Rough (Not Running On 1 Bank)

[mightymetro]

Hi all, new to the forum and looking for some advice if anyone can help

Purchased my wife a 4.6is X5 (2002) and its been a bit of a nightmare trying to sort out various problems in the first month of ownership. I am stumped with the latest problem.

The X5 had a quite severe oil leak under the car when i purchased it so i took it to the garage to take a look. The garage took the bottom covers off and the engine cover. When we took the engine cover off the top they noticed that the rear 2 pipes from the CCV had perished and split. The car was still running fine at this point.

As a side note i have covered around 600 miles since purchase and a week after buying it i had this same issue of rough idle / loss of power after a 60mile motorway drive and then coming into a residential area. Got home and looked around but couldnt see anything. Next day all back to normal and never happened again.........until

Garage have just replaced the rocker gaskets and oil leak now cured :-) Yay

They also replaced the 2 hoses from the CCV that were perished and split with new ones. They have run the car up and said everything was fine, idle perfect and running perfect. I collected the car and on start up noticed it did not fire straight away. Once it fired up it idled a little rough so took it for a run and car is better above 2000rpm but still feels lacking in power. As soon as you come to a junction it will start rough again and stall or try to stall.

I took it back to the garage and they have been taking a look and it seems the drivers side bank is not running. When you dis-connect the coilpacks on that side the idle / running of the engine does not change at all whereas if you take one from the passenger side bank it starts cutting out so it seems the drivers bank is not running. Exhaust from passenger side is pretty sweet but drivers side is chugging.

Also, when you disconnect the CPS (from previous experience of a 540i) on both sides absolutely nothing changes with the running i.e the engine will just keep on running the same with both cps disconnected.

Stored previous codes are 02 sensor fault, excess trim bank 1, excess trim past adjustment or something to that extent. All cleared and there are no faults shown.

Garage have said that they are at a complete loss as to why this is.

Any help or advice would be really appreciated

[Greydog]

I would have them check all wiring on the coil packs, when working on the rocker covers they could have disturbed or broken an earth connection or power feed.

[Guest Mister Dabsy]

Is that pre and post lambda?

We know any oxygen sensor(s) fault will wind-up the ecu

[mightymetro]

Just a quick update as i realise how frustrating it can be when there is no closure to a topic.

Turned out to be the Vanos control solenoid for that bank. Replaced with a new one from BMW (about £80) and all sorted :-)............................ until 17 miles later when the cam chain guides broke :-(

Thanks again for the replies