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Discussion Starter #1
Has anyone figured out way to keep flaps open. Are they vacuum controlled or by electric motor. My other car flaps operate via vacuum and it's pretty simple to either shut vacuum off or keep active. I've tried to find the flap actuators but not located them.
I'd like a little more sound. I liked the way my 2005 R 171 sounded
 

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There's a thread on the AMG lounge at the moment covering how the exhaust flaps operate and what they do, doesn't say if they're vacuum or electically actuated however.

RR
 

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doesn't say if they're vacuum or electically actuated however.
they're electronically operated - you can see the connectors to the actuators at the rear when you look under the car. I had a discussion about this with the dealer when I had the problem with my car.

I don't think it would be rocket science for someone to figure out what signals need to be sent to the actuator to get it to stay open (remember that they're multiple position flaps), but I guess there haven't been enough R172 55s sold to have someone with the necessary know-how to figure it out.

 

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Flaps has an electric motor. Disconnect the cable when the flaps are fully open. Then the flaps are 100% open. I have tried this, but just in the garage. I have not tested this at speed due to snowy roads, but only at startup and it sounds good.
 

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Flaps has an electric motor. Disconnect the cable when the flaps are fully open. Then the flaps are 100% open. I have tried this, but just in the garage. I have not tested this at speed due to snowy roads, but only at startup and it sounds good.
Are you saying flaps are fully open when engine is off?
 

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Turn the ignition to on (2 steps). Use a flashlight and look at the flaps and remove the cable when the flaps are 100% open.
 

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this certainly sounds like an interesting plan - my reservation is whether the flap motor provides resistance, else there's the risk of exhaust gasses closing the flap when driving. will be very interested to hear how you get on with it (and some audio/video of it in action if you get chance)
 

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I've had a good look at this today - I can see that when the key is put in the ignition and moved to the first position, the flaps open fully, then they close again when it's moved on the the second position and remain closed when the engine is fired.

Looking at the connectors, I see there are 2 for each side - the first on the actuator itself (as per the pic earlier in the thread), and a second cable-tied under the rear wing. The right hand side wing connector has a cable running off from the other side of it, which I guess might feed to the left hand side wing connector.

all the connectors looks to be the same, but the space and viewing is so limited that I couldn't really see how to disconnect the plugs - I did try by feel, but failed.

how did you disconnect yours slk55nor?
 

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UPDATE: I did notice something weird, but as I only drove it a couple of times I dismissed it, but someone else has experienced the same thing so I'm posting it here. I noticed a drop off in power between 5k and redline.

I'm really not sure why this would be, as I thought that at full throttle the flaps would be open stock - but as this effect has been seen on more than one car, something is clearly affecting top end with the flaps open like this

- - -

Big thanks to slk55nor - the job is now done.

Weirdly, this time I had to move the ignition on 2 clicks, then back 1 to get the flaps to be fully open - I've attached a pic of the fully open flap.



I followed slk55nor's example, and released the clip in the side of the rear wing rather than the one on the actuator itself. Here's a pic of the right hand side connector



I still had problems releasing the white clip (at the right of the connector in the pic) - in the end I used a small flat head electricians screwdriver and pushed the blade in a few mm between the white clip lip and the black connector and then pulled the connector away from the socket and it came apart with no problem.



As per slk55nor's example, I then used black weatherproof pvc tape to cover all the now exposed connectors/sockets and cable tied the right side connector to the socket and the left side I looped back and tied it to itself.

I've also done a quick comparison video - it's far from ideal as the engine was cold and it's in a big garage, but you can hear the difference in note.


I'll do some proper videos as soon as can get chance.

Massive thanks to slk55nor.
 

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when I had problems with the sound from my exhaust the dealer told me there were no diagnostics for the flaps so it makes sense that it didn't throw any codes. Definitely an easier job than plugging the vacuum lines on an r8!

what is your cause for hesitation about leaving the flaps open on the slk?
 

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Discussion Starter #15
Oops. Didn't intend to delete that post. hit wrong button. Our results the same. I unplugged the actuators. You can reach up around the tailpipes and get to the plugs. The left side is more difficult since it is forward on the actuator and hard to see. Pull back on the grey tab on plug and then pull out plug from actuator. I also taped up everything to keep out dirt. Will leave open and see what it does at highway cursing speed. It sounds like it may have some drone but I hope not. Yes it is much easier than the R8.
 

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Lol. Didn't even think about that. Can't wait to try it. This is first car ever owned with cylinder deactivation. Kind of oxymoron with performance engine.
 

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Lol. Didn't even think about that. Can't wait to try it. This is first car ever owned with cylinder deactivation. Kind of oxymoron with performance engine.
yeah - I'd use it more if it didn't come strapped to stop/start which I positively hate.
 

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ill leave open and see what it does at highway cursing speed. It sounds like it may have some drone but I hope not
I took the car out earlier to hear what it's like on the road with a warmed engine. I took some video with a gopro and a zoom h1 sound recorder which I'll edit and post up later to give an impression.

It's pretty clear that the exhaust has been tuned to work with the flaps - there's a very bassy "woob woob" sound when coming off the throttle and you were right that cruising in high gear at low revs does introduce a drone - it really is awful to the point of being unbearable in 4 cylinder mode. Obviously with heavy throttle there's no difference in noise as the flaps would have been open if they were behaving normally. At the lower revs there is clearly a deeper bassy tone there. The overall impression reminds me of a slightly muted aftermarket exhaust, rather than oem.

The weather here is still pretty crappy, very strong winds and rain, so I couldn't test it top-down.

The jury is still out for me as to whether I'll keep it like this too.
 
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