bmwcrocop

Update: star code 0522. Diagnosis of tumble flap intake manifold.

Tumble flap shafts sticks in non actuated position.

What would cause this code? Would it cause a misfire?

The Thomas J

The w211 had similar issues. Basically the flap is plastic. The hinges become brittle over time and crack. Or they get sticky from what ever and causes the flap to stay in one position. It's a real pain in the *** and yes it can cause a misfire.

KNBS550

Unfortunately, this is a known problem with the M272/M273 engine. Mercedes-Benz went on the cheap with the intake manifold flap by making it out of plastic and not metal of some kind. There are metal replacements for the flap you can buy online. The part of the repair that sucks is the labor to remove the intake manifold. Certainly you can do it yourself but it is time consuming even if you know what you are doing.

The Thomas J

BMW did as well. BMW calls it a D.I.S.A. Same issue. Much easier to replace than an MB one.

bmwcrocop

Where can I buy the metal flap kit for the S-CLASS??


Amazon had it for other vehicles.

KNBS550

Check out this youtube video. I think he'd have a new tumbler flap for you. http://www.agatools.com/

bmwcrocop

Update:

Ok .. Got the intake repaired and re installed.. Again the car ran for about 30 sec in good standing and then dropped the 8 cyl. When it drops cyl #8.. Looses power from Ecu to injector.. However the coil remains active.. Thus it appears their is a final stage in the ECU that it fails when it gets hot.. The issue is that it needs to run for a bit to kill the circuit..

Thoughts?

gsholz

Not necessarily a problem with the ECU. It could be the ECU is turning off fuel to #8 after it detects a misfire which is the correct thing to do.

It comes back to why does the misfire exist. From your other posts I see that you replaced plugs and coils. Did you ever exchange the #8 injector with another cylinder to see if the misfire tracks the injector?

In your other post you mention that your compression is lower in #8. If the low compression persists it could be the cause for the misfire. It might make sense to use a bore scope to inspect the valves and cylinder condition.

Also double check any vacuum hoses for leaks that connect to the manifold close to the #8 cylinder.

bmwcrocop

Fuel injectors were switched. Manifold repaired. Compression was low and no leaks.

I'll ask if the valves and cylinders were bore scoped.

I'll have him check vacuum hoses as well. I'll see if the ECU repair fixes the issue.

Will report soon.

bmwcrocop

If there was wear on the valves, cylinder head or valve seats --- wouldn't the cylinders knock?

The Thomas J

Not always. IMO you have two different issues happening and the manifold tumbler was a separate issue. Some one else needs to chime in here. Does this version of the motor also suffer from the balance sprocket issue that the pre-2007 w211 engines had?

gsholz

The ECU detects misfire by looking at the data from the crank position sensor. If ignition of cylinder #8 did not produce enough angular acceleration, a misfire is assumed/indicated.

A cylinder with low compression can produce less twist than a healthy cylinder and show up as a misfire.

Since you already replaced the crank position sensor and eliminated the injector, I'm afraid the remaining cause points to the cylinder rings and/or valves.

The idler gear might be an issue if your engine serial number is less than 2739 30 088612.

jcwbenz

Is this a repair that should have been done with the manifold off? or is access separate?


Are valves and cylinders expensive to repair?

gsholz

I'd redo the compression test and leakage test first. Determine if the valves or the rings are the cause of the low compression. Use a bore scope to get a visual of valves and cylinder walls. If everything looks good, reset the code and drive the car and see if compression comes back up.

Chazz Michaels

I hate to dig up an old thread, but more often than not there is never a conclusion to these posts. After all my research, I would like to add to this. There are several people complaining of misfires after having tumble flap issues. A gentlemen on MB world ended up finding out that the issue on his stemmed from pieces of the inner tumblers coming apart and getting sucked through the valves. The pieces are generally plastic and soft, therefore they can get burned into a valve seat causing the valve to hang open slightly. He had bore scoped the valve seat and found melted plastic between the valve and the seat. He ultimately resolved the issue by going through the exhaust manifold and manually burning away and cleaning the excess plastic with the valve partially open. Once the engine sees suitable compression in the cylinder, it should fire normally and burn away any excess.

I know many people complain of this same issue, so I would recommend a leak down test to find out if you have a leak into the exhaust, the intake or the crankcase. If your rings and cylinder are in good shape, there’s a good chance this could be causing the misfire in cylinder 8. This is less for the OP, and more for anyone searching this same issue.

dtonjes

Also from agravating experience a stuck open injector will give low compression if tested immediately after the car is driven or tested without killing the fuel pump. Ah duh