‘06 3.0si Rough Idle Troubleshooting Help and Other Questions

[Mainzer05]

Hey guys,

I recently bought an ‘06 3.0si with 96k miles and the car has been pretty sweet but the car has felt like it’s only making maybe 80-90% power, it’s mpg is lower than average even with tame driving and it has an idle that bounces around for a few seconds only on rough start ups like here:

[youtube]https://youtube.com/shorts/MUsbMqor8Fc? ... MmE9WkdovT[/youtube]


Things I’ve done so far have been:

-New battery (needed a new one regardless)
-New spark plugs (wanted to change regardless)
-Used a scanner to look at fuel trims and all the numbers looked good
-Cleaned the MAF
-Checked the air filter
-Ran some Techron
-Pulled the VANOS solenoids and cleaned them. They looked clean on the exterior but are the original ones. They made no noise when shaking and they made about this much noise once I sprayed them a bunch with cleaner:

[youtube]https://youtube.com/shorts/0agQiKLWmEA? ... UVku0Owpts[/youtube]

They both sounded like this after cleaning. Does that seem like a pretty tame rattle and they are likely shot? If so, I was gonna buy FEBI replacements from FCP with the lifetime guarantee but then I saw these on eBay:
https://www.ebay.com/itm/394977644769?f ... BM3I_DzJtj

https://www.ebay.com/itm/204563177805?f ... BM3I_DzJtj

I never buy parts of ebay so how do I know these are actually genuine BMW? I can’t see the BMW stamp in any of the pictures. Thoughts on their legitimacy?

-I also pulled the large DISA today and it looked quite good to me. No play in the flap, no missing green gasket. A bit of sludge buildup but this car wasn’t driven much over the past 4 years by the prior owner. There was a bit of oil on it. Should the unit be completely dry or is a little oil normal? This is how it looked:

3133BCD7-A80D-47A9-B208-8F946DD6336D.jpeg (99.32 KiB) Viewed 274 times

C34DD627-D57C-4C08-8001-C579DB9FDACB.jpeg (93.56 KiB) Viewed 274 times

It also has this what looked like rust on on section but it’s plastic so I’m not sure what that could be.

92A97A63-F91D-4BA1-A323-45E3C5381F6D.jpeg (97.62 KiB) Viewed 274 times

Do these look normal to y’all?

I put the cleaned vanos solenoids back in and the bouncing warm idle still happened, so maybe it is the VANOS and I just need new ones or maybe it’s something else. Do the small DISA fail often? That one is much tougher to check so I was hoping to avoid that. Anyway to know if it’s the CCV without pulling it? That is a pain to get to. I guess I’ll do a smoke test at some point so see if I have a vacuum leak. What are your thoughts?




My 2 miscellaneous questions.

1) I had swapped the manual Trans Fluid and was dumb and did so with the front raised and ended up overfilling it. I finally was able to raise the car again level and drain the excess. This much came out:

774A8B5C-E448-446F-8025-3EC9EC8A436D.jpeg (149.39 KiB) Viewed 272 times

I would estimate about 1/3 to 1/2 quart overfill. Is there anyway to know if any of this could have gotten on the clutch? Even if it did, would the oil burn off over time?

I tried testing for a slipping clutch by going up bill in 5th gear at about 2200 rpm and then going WOT and the revs (and speed) did not shoot up. I also did a slow pull and fast pull between 3k and 5k rpm in 2nd gear and it looked normal. Does the speed it revs seem normal?

[youtube]https://youtube.com/shorts/lJx5ZXJM9RI? ... S7EboW7DHd[/youtube]

[youtube]https://youtu.be/GIxwtatbZeQ?si=SD40lEMPe49idId7[/youtube]

2) When remove the intake piping, I noticed the rubber around the intake box is someone caught in the lip of the intake. I have moved it back how it should be but it doesn’t stay. Could this impact anything?

69AF2954-1EC2-4558-A818-20D4C2D6C2FE.jpeg (173.16 KiB) Viewed 272 times

Thanks for all the help. This is my first BMW and I enjoy learning how to do all my own work and researching and all, it’s just a lot to learn and I always have tons of questions, so I appreciate all the help and answers!

[r3vmatch]

Hi,

I'm not sure why you didn't get any replies other than maybe this should be under the 'Problems' subsection.

But, based on what you posted and the condition of my own Z4 3.0si @ 72K miles which I was ALSO chasing a rough idle issue on:

- Your CCV and hoses probably should all be replaced. My CCV was "clogged" but the car threw zero codes. When I pulled it, it looked like it needed heart bypass surgery. It's not "hard" to do, but time consuming removing the intake, hoses, brake booster hose, intake resonator, etc.

On my car the CCV failed, let oily by products back into the intake and my large DISA looked like yours -- gasket OK but covered in oil

- I think there is a good chance you INNER DISA valve (the smaller one) has a failed green gasket because if/when the CCV fails, it eats away at the rubber. This was the case for me for sure, the inner DISA still worked but was missing green rubber which meant it no longer worked as a valve and let air / gases leak back into the intake

- Changing out the INNER DISA means pulling the intake so at the same time I replaced the starter which is EASILY accessible if you pull the intake. Might also be a good time to replace the regulator / brushes and bearings on your alternator since that's accessible too.

If you're in the US, drop me a PM, I have some basically brand new BMW OEM VANOS solenoids I pulled from my car, someone else must have been troubleshooting this before me, I went ahead and replaced mine with new ones (no difference in idle).

Last, after doing all of this work + new plugs + new coils I still had a rough idle (but significantly improved and much more power after changing DISAs, CCV). I had my Eccentric Shaft Sensor replaced as well (ugh, including all the valve cover gaskets) with an OEM VDO part and the idle now seems correct.

[r3vmatch]

Addendum:

I tried to see if anyone had luck with "aftermarket" DISAs and most people said their non-OE units (originally made by Mahle) ended up failing. I bit the bullet and replaced both of mine with new BMW OE ones (Mahle) for peace of mind. After ALL the work to pull the intake, etc might as well pony up for the new part given the savings of not paying a mechanic. If you're in the US, Bimmerworld sells an N52 'intake upgrade kit' for approx $700-ish which includes both BMW OE/Mahle DISAs, which is the cheapest I found. I still bought BMW "OE" intake gaskets from the dealershipp (ugh $60) to not run the risk of the Victor-Reinz ones leaking, which I've heard their gaskets can do for the Valvetronic motor seal.

I was also quoted outrageous amounts of money (I think $2K USD) parts+labor to do the DISA+CCV from a local shop, I was able to include a new starter and new brake booster hose and new throttle body (completely un-needed but worth a shot troubleshooting rough idle) for far less than $2K. I also replaced my crankshaft position sensor ("while you're there") with an OE VDO part and my camshaft position sensors with VDO parts "for more peace of mind".

In the US, FCP Euro seems to have the best price on 'OEM' sensors like VDO if you decide to get the Eccentric Shaft Sensor.