2006 Z4 M Roadster Rough Idle & Loss of Power

[StinkyBeard]

I'm at the end of my rope here.

Started a rough idle 3 weeks ago.

It spent over 2 weeks in the shop where they replaced 6 coils due to misfires on several cylinders. No change. Still throwing a MAF code, so they popped a new MAF sensor in. No change. Next they inspected the fuel injectors where they saw 4 that were clogged. 6 new injectors installed. No change. They did a leak down test which came back with no findings. Only 3% leak down. They finally used an auto tech computer to actuate the vanos manually which they said it failed 3 different tests. A second technician verified and both agreed a new vanos was in order. Since the computer wasn't throwing a code I said no and picked up the car.

This weekend I sprayed everything down with starter fluid looking for leaks. Nada. I then pulled the air intake manifold and cleaned the throttle bodies and the idle control valve. All with no change.

I also put a balloon over the oil fill cap (cap removed) with the car idling and the balloon did nothing. Didn't suck in and didn't blow up.

So here I sit, throwing misfires on 5 cylinders and a mass air flow system fault but no idea where to look next.

2D06 air mass system
29D1 Misfire, Cyl. 5
29CF Misfire, Cyl. 3
29CE Misfire, Cyl. 2
29CC Misfire, several Cyls
29D0 Misfire, Cyl. 4

Massive loss of low end torque and a really rough idle. Never stalls but the entire car rocks/shakes at idle.

Any suggestions?

Thanks in advance!

[Clearancediver]

Repair the Vanos as diagnosed...

http://www.beisansystems.com/faq.html

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[Clearancediver]

Repair Vanos...

http://www.beisansystems.com/faq.html

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[StinkyBeard]

Dropped it off at the dealer. They confirmed the VANOS is fine.

Recommended replacing the aFe cold air intake with the OEM air box. Anyone have one they want to sell?

Not sure how 8000 miles on the aFe intake no means I need to replace it...so frustrating

[Clearancediver]

Clean your idle control valve to see if it's an issue. Actually a pretty easy DIY on my engine to remove and clean.... Cleaning it will remove a potential cause and will only help the engine idle better.

FWIW doing the VANOS upgrade/replacing of o-rings made a huge difference in mid range revs where it would surge at 4K rpm or so... Much smoother/stronger/linear since we did the upgrade. I didn't have any obvious issues except for the surge in the higher revs.... But when we took the caps off the Vanos cylinders and turned the unit over/ upside down, one cylinder fell out just from the motion of being turned over.

Remove the "rubber" ducts from MAF backwards/onwards to throttle housing and check for tears/cracks etc...

Check crankcase ventilation valve for blockage.... Google symptoms...

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[Clearancediver]

Sorry missed where you said you cleaned the idle control valve.... Although it still could need a further cleaning as it wouldn't be the first time that additional cleaning solved a problem.

A really perplexing problem though.

If you had INPA software I'd suggest you look at the engine data in real time to see what's happening with the cylinder firing etc. It also gives you the ability to test your Vanos operation yourself.

Sudden thought... Have you checked your voltage regulator output...might be a combination of little things which are building on each other....

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[StinkyBeard]

Just called the dealer.

They are recommending removing the valve cover to inspect everything happening under the cover. broken valve spring, gears (guessing vanos), etc.

Basically looks like a $750 engine inspection to me. Last shop did a leak down test, which came back fine.

I have no intention of paying them $4000 if they find the VANOS is jacked but if they take that cover off i'm already in 25% of the way.

Also said I should consider adjusting the valves....typically a $1300 job.

not sure what to do at this point...rebuild the VANOS as it has known issues, replace the OEM airbox as the code being thrown is too much air entering the system, yoink the valve cover...

So many options

[Clearancediver]

Bad gas????? Did it start rough idling after refueling... Did you change gas brands from the usual...

O2 sensor issue....check for damaged wiring to sensor(s). Again... INPA software would allow you to check to see O2 sensor readings in real time.

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[StinkyBeard]

Funny you ask. Before this happened...nearly a month ago now...I had started filling up and realized I was dumping 89 octane in vice 93. I stopped mid fill up and switched over to 93. I'd be shocked if that was it...but its more data. I've since filled up 2 more times since then.

I guess it could be an 02 sensor. Haven't put my hands on them per se to inspect wiring.

INPA software. Gonna have to do a little research on that. I did buy the wifi OBD2 dongle so I could use the iphone and dash command which gives me waaaaaay to much data to consider. no idea if the values its providing are within spec or not.

[BimmerBreaker]

The car will run on 87. If anything it should run a tad smoother as it isnt working as hard to combust the 87. And if you mixed 89 50/50 with 93 you get 91 (that is how gas stations give you 89... they only have two tanks, 91 and 87, when people pump 89 it just mixes it).
Also pretty sure that balloon trick is mostly used for M54 engines not the S54 (which has NO relation to the M54 at all, other than sharing 2 of it's engine code digits)

Can you let us know what codes/symptoms is it CURRENTLY exhibiting? What has been done to it to try to remedy the problem so far? Sounds like a vacuum leak to me... but hard to say for sure

[StinkyBeard]

Dealership pulled the valve cover. The diagnosis!!!!

Broken Exaust Tabs on the VANOS.

The bill!!!!

$9000. NINE THOUSAND DOLLARS!!!!!

Had it towed to the house. There she sits...lonely...and cold.

[DerekZ4]

Dealership pulled the valve cover. The diagnosis!!!!

Broken Exaust Tabs on the VANOS.

The bill!!!!

$9000. NINE THOUSAND DOLLARS!!!!!

Had it towed to the house. There she sits...lonely...and cold.

WTF, 9K? Please explain?

[Clearancediver]

Lots of posts and info here...

https://www.google.ca/search?q=N54+v...&client=safari

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[StinkyBeard]

WTF, 9K? Please explain?

Dunno man. New Vanos. Two new ew sprockets. Drop the oil pan. Ridiculous.

I took the valve cover off tonight and saw the broken tabs. The good news is they are still in the VANOS oil pump! In other words, likely won't have to drop the oil pan or have to replace the sprockets! yay.

What I can't figure out is how to get the VANOS off. The subframe is 1" from the VANOS and removing the subframe doesn't look plausible without total disassembly. All the DIY posts I've found don't have pictures any more, so I don't have any other references. Some have suggested to use a pry bar, but man that subframe is SOLID. no way it moves with pry bar.

Anyone have some experience popping the VANOS off a Z4 M?

[Clearancediver]

I did the Vanos on my '04 M54 engine a couple months ago.... Remove the two bolts on the top of the cross frame on each side where it bolts to the fender... Back off the single bolt on the inside of the cross frame at the top. Those bolts needs to be backed off about 1/2 max...or removed if you want. That allows you to "flex" the cross member with a pry bar appropriately placed .... enough to allow the Vanos to clear the studs. I "flexed" and my son "removed" the Vanos assembly.

We also did the water pump since we were there... The cross member interferes with the water pump as well. As per the TIS... We removed the top bolt on the driver side motor mount. Using a 2x4 under the oil pan at the front of the engine to spread the lifting pressure and a lifting Jack.... We raised the engine until the bolt almost exits the bolt hole ... approx 3 cm. The engine rotates slightly to the passenger side as it lifts and allows the water pump shaft to clear the cross brace....

It's a 5 min prep/replace for both procedures....

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[DerekZ4]

I'm still at a loss at how one can come up with 9k. I would have asked the dealer to write it out in a quote. May have been good for a laugh like when they quoted me $756 for control are bushings too.

[BimmerBreaker]

Lots of posts and info here...

https://www.google.ca/search?q=N54+v...&client=safari

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Thats about an N54, an engine that never made it into the E85 Z4. These Z4's saw the M54's and N52's, the M's got the S54's. The N54 was the early turbo engine fitted to "X35i" models (135i, 335i, etc).

I did the Vanos on my '04 M54 engine a couple months ago....

Also just have to note here that your VANOS system has no relation to OP's system. The S54 is not derived from the M54. The S54 is derived from the euro S50 which derived mostly from the M50 but with substantial differences. As such the S54 shares basically nothing in common with the M54 so repair procedures are going to be different between the two cars. Really, the only similarities between those two VANOS systems is what they do.

Dealership pulled the valve cover. The diagnosis!!!!

Broken Exaust Tabs on the VANOS.

The bill!!!!

$9000. NINE THOUSAND DOLLARS!!!!!

Had it towed to the house. There she sits...lonely...and cold.

I highlighted your biggest problem in red. Do not take a car of this age to the dealership. IMO never take a car out of warranty to the dealership. Every dealership for every brand makes MOST of their money off the service department. When you bring in an old, maintenance intensive (BMW M) car to the dealer they just see dollar signs.

Find a reputable local independant BMW mechanic. Ask local enthusiasts if you don't know any shop or can't find one. Have them diagnose it, worst case scenario you swap in a whole new engine for $5k and you sell what you can from your current engine to recoup another $3k or so to foot a $2k bill all said and done. If you could do the work yourself, you can probably end up with no financial loss at all... but I'm assuming thats not in your comfort zone. All I'm saying is to be thrifty here. The S54 in your car has been around for 15 years, thats old enough now that any decent third party BMW mechanic know them inside and out. Call some local shops, get some quotes, make some stuff happen.

If you don't want to deal with it then I'll extend an offer to buy the car for $8,000 less than market value

[Clearancediver]

Point I was making was to google to find out about his Vanos issue......how to repair etc.

The OP was concerned about removing Vanos with the crossbrace in the way. I was stating how to ensure clearance/gain the necessary clearance if required....

Basic diagnosis and repair techniques...

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[StinkyBeard]

I'm going to attempt this repair myself...although way out of my comfort zone.

I bought another car to drive in the mean time so I can take my time and make sure I get it right.

Bought a ton of new tools, and the required BMW timing tools. Bought the TT hub and the Besian seal kits to rebuilt the vanos. Also going to do the timing chain guide and a valve job while i'm in there. Should be a good learning experience.

Finally found a few good forum posts that show/tell how to deal with the subframe that is in the way, so I think I can make this happen in a few days time.

Thanks for all the help boys. The indy shop i went to kinda let me down. They shotgunned new coils, injectors, MAF before doing a test on the VANOS. By that time I was skeptical that they had any idea how to work on this car. Turned out they were right, but since the cars computer wouldn't throw a VANOS code I couldn't justify dropping $3500 for a new vanos with them. As it sits today I'm out $1000 in coils, injectors, O2 sensor. $700 at the dealership to take the valve cover off / diagnostics. $400 in new hand tools. $750 in the TT hub. $600 in gaskets, seals, washers, BMW timing tools, etc. I just threw up in my mouth a little...

The good news...in doing this myself...when i pulled the valve cover off, I can see that both tabs are broken. I can also see that both tabs are still in the oil pump hub. Hoping that means I don't have to drop the oil pan like the dealership said i need to do. They were also going to replace both sprockets, i assumed because they had been damaged. Neither are from what I can tell.

Lessons I've learned:

1. Don't drive an aged BMW as your daily driver without a backup car when she breaks down.
2. Don't go do the dealership.
3. Working on a BMW is way easier then working on a Ford or Chevy. Everything comes apart and goes back together way easier. Very impressive engineering which can't be appreciated until you dig in.

[BimmerBreaker]

Finally found a few good forum posts that show/tell how to deal with the subframe that is in the way, so I think I can make this happen in a few days time.

Wow! Good luck! Most doing this for a first time would be happy to get it done over maybe a couple weeks... but thats dedication!

The good news...in doing this myself...when i pulled the valve cover off, I can see that both tabs are broken. I can also see that both tabs are still in the oil pump hub. Hoping that means I don't have to drop the oil pan like the dealership said i need to do. They were also going to replace both sprockets, i assumed because they had been damaged. Neither are from what I can tell.

Lessons I've learned:

1. Don't drive an aged BMW as your daily driver without a backup car when she breaks down.
2. Don't go do the dealership.
3. Working on a BMW is way easier then working on a Ford or Chevy. Everything comes apart and goes back together way easier. Very impressive engineering which can't be appreciated until you dig in.

My .02; drop the oil pan anyways. Its easy insurance and it'd be a shame to do all this work to fix it then suck up a piece of metal and ruin your oil pump and grenade the engine.

Regarding your first point in the list there, I drive an aged BMW as my daily driver with another aged BMW as a backup! Doesn't always work out in my favor. And the third point is very true. I try to tell my friends that when they say "I love my Honda/Chevy/whatever because its cheap!" then I remind them that its cheap because its designed to be put together cheaply, but no thought was put into taking it back apart. BMWs on the other hand are designed to be worked on. Little access holes to everything, things being positioned just perfectly to give clearance when needed... yes, its quite a pleasure working on BMWs IMO

[Clearancediver]

Glad to see that you've kept most of your sense of humour.... Make sure you buy a set of low rise ramps to drive the car up on. That should give you the room to remove the subframe to get to the oil pan. It's not that awkward to remove the subframe lying flat on your back (done it myself).

I like low rise ramps when working underneath the car... Gives me more sense of security when working alone.

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[StinkyBeard]

Last night I was able to yoink the VANOS off. Surprisingly easy. Was able to retrieve the tabs which were lodged in the oil pump. Still mixed on pulling the oil pan off. Waiting to pull the broken hub off to see if anything is missing. If there is I'll pull it. Quick question though...so the oil pump pulls oil out of the pan, then up through the filter, then into the engine? If so wouldn't a small shard of metal get caught in the filter as opposed to grenading the engine? Granted that piece of metal could kill the oil pump first, but if its small enough...maybe no harm done?

Got about half way through the VANOS seal replacement. Probably get that finished up tonight and maybe, just maybe, get the new hub installed. Still waiting on the timing tools to button it back up.

[BimmerBreaker]

Its very unlikely for a large piece of debris like that to get sucked through the engine (large as in - big enough to see and touch). It really won't happen, and I'm pretty sure the S54s also have a mesh screen before the oil pickup.

12 in one hand a dozen in the other. There is a very small chance of failure resulting from the debris in the pan, but on an engine like that I wouldn't even risk it.

[JimsR]

10yr bump. Anyone know if its possible to reinstall the vanos on the Z4M with the splined gears attached? I don't see how that's possible with the crossbrace in the way.