Im gonna say he replaced the plugs...


:cool:

I thought he may only have replaced the plug on cylinder 8 even though plugs was plural. Oh well.


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Yeah, I guess we will find out....

Well here we go again. Mine started doing the exact same thing(but its a 3.0si). I just fixed some rough running issues and hesitation from a dead stop. The main culprit was my DISA valve, I pulled it out and the entire flap was just gone. I tried look in the intake manifold to see if the flap was still in there. But my guess is someone removed it on purpose thinking it would add power, just like deleting IM flapper in a Honda. When doing my VCG, I found that the spark plugs were very worn out, so I replaced all of them and the coils too.

The DISA really had it running smooth for a bit, then suddenly it started running VERY rough on cold starts. And now that the temperature is dipping below zero at night, the vehicle will barely run in the morning on first start. But once it runs for about 30 seconds the idle smooths out and it runs fine. However it still have dead stop hesitation......again.

I didn't change the intake manifold gasket when I had the intake manifold off for vacuum line replacement awhile back, so that could be a significant cause of vaccum leak now. But it is still weird that the vehicle smooths out so quickly, and doesn't seem to have issues on a warm start.

Going to unplug the MAF just to see how she starts. That might give some indication to what is going on. Probably going to replace the IM gasket just for good measure, it's very cheap anyway. Might as well throw some Pre-cat O2's at it as well since they are surely as old as the vehicle.

How crappy are the intake tubes on these X5's?? On the E46's they were garbage, they develop micro cracks and cause misfire issues due to vaccum leaks.

Yeah I changed all spark plugs less than a year ago, but might as well check them to see if there are any problems with it.

The n62 does not have DISA valve so we can rule that out.

Oxygen sensors have been changed but I had the same errors that another member had, misfire on 4,5 and 8. So I´m gonna re-check spark plugs and make sure that tey are fine.

How many miles on this vehicle? It doesn't appear you've done coils yet. That's another thing that will make you chase your tail troubleshooting. You can swap coils all day long and watch the same misfires continue to appear. Replace the coils and suddenly problem is solved. At 20$ a pop it's a worthwhile venture if you can't locate a vacuum leak to repair.

About 103k miles. But if it were coils, the car would have misfire all the time.........maybe I´ll just change coils and spark plugs again and see what happens.

*edit* ignition coil on cyl 8 has already been changed.

Oh I don't think coils are your main issue. At 103k miles, they are definitely due though.

Also, worth mentioning. Again, not your main issue, but what plugs did you use? BMW's hate those 4 prong plugs or anything fancy like that. You want standard replacement, Bosch or NGK plugs.

I just unplugged my MAF the other day for a cold start, and it fired right up no issue. Small surge in the RPM and then settled right out like normal. No misfires and stalling. That basically confirmed for me I have a vacuum leak. A bit ironic that we are both having the exact same issue, but one is 4.8 and one is 3.0.

I just hate those Nxx engine from BMW lol. I used NGK 3199, if I unplug the MAF it runs like hell, so the MAF is ok and no vacuum leak.

Already spent over $9.000 in reapirs on it, and just about geting fed up with that piece of metal.

*edit* I just found out that NGK 3199 are not the right spark plugs, I was looking at another car when I took them out of the shelf. Will replace them with the right ones and hopefully the car will be fine :rofl:

Use NGK 4294


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