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Resonance flap not working

9K views 55 replies 19 participants last post by  ianwood 
#1 ·
The flap is not working on my 3.6.

Ive changed the solenoid from a car that it was working on.....no difference.

Changed the actual thing that open the flap

Tried another ECU aswell!

Still no joy!

Any ideas?
 
#2 ·
I had the same problem some time ago. You probably have to change all the vacuum rubber hoses that are involved. Buy a bit more than 1 meter of the hose and cut copies based on the old ones. Do remeber to also change the last bit on the plastic hose that goes by the ignition distributor and down to the exhaust pump.
I think you will end up with 7 or 8 short hoses that you need to cut and replace.

After that you should get it to work.

Good Luck :)
 
#5 ·
But it does self test on ignition No 2........or not? The other M5 self tests.


Hence why I assumed it was not working.

Only other ways are to look whilst on dyno or remove bonnet and go for a drive!.....removing bonnet idea not so good I think.:3:
 
#7 ·
Or maybe I can get a camera in there with a very bright light?

Anyone got a camera they want to lend me? Cumon, help a bloke out, let me use your £1000 sony camera with Karl Ziess lense so I can see if my flap works.

Promise I wont melt it!:cool2:
 
#8 ·
Cyrus:

Take a look at this resonance flap test procedure from the E34 M5 FAQ:

E34 M5 FAQ: Resonance Flap Test Procedure

Then if you need to rebuild the resonance flap let me know, as a friend of mine locally here in the Bay Area (Jason Weaver) had written a great step by step procedure after rebuilding the RF on his '91 AW M5. I thought the draft version of this was also uploaded to the FAQ as well but I did not se it when quickly glancing through the contents there now.

BTW, Just what else did you have planned for that digital camera you were hoping to borrow. Hmmm... ;-)

Hope this helps.

Regards,

Ken Little
Bay Area M5's

 
#10 ·
Are you talking about the valve on the top right side of the inlet manifold with the bolt that controls the amount of travel that you can move with your finger?

All you have to do to test it is put a blob of grease on the bolt then drive it round the block, if it is working then the grease will be on the flap mechanism too.

No need for cameras, rolling roads or trained gerbils with minature miners helmets :3:
 
#11 ·
London Mike said:
Are you talking about the valve on the top right side of the inlet manifold with the bolt that controls the amount of travel that you can move with your finger?

All you have to do to test it is put a blob of grease on the bolt then drive it round the block, if it is working then the grease will be on the flap mechanism too.

No need for cameras, rolling roads or trained gerbils with minature miners helmets :3:
hiha
hiha

That was a good one....
 
#12 ·
You don't have to remove the intake manifold, just the plenum/intake. Mine was hooked up wrong after my rebuild and wasn't operating. While we were down there we replaced some vacum lines.

If you know someone with a vacum test gauge you can hook that up to find out if vacum really is the problem. On start up it cycles through like everyone says.
 
#17 ·
London Mike said:
As Pepsmeister said, the E34 M5 doesn't self-test.
Mike,

You have a 3.8? My 3.6 does cycle for sure and it really made a difference when we got it working in terms of low end power and smoothness.
 
#18 · (Edited)
KKelly said:
Mike,

You have a 3.8? My 3.6 does cycle for sure and it really made a difference when we got it working in terms of low end power and smoothness.
Yup, I have a '95 3.8, it doesn't cycle (and I don't see how it could as it is vacuum driven) and it passes the 'blob of grease' test. It also drives fine with no huge holes in the power curve.
 
#19 ·
London Mike said:
Yup, I have a '95 3.8, it doesn't cycle (and I dion't see how it could as it is vacuum driven) and it passes the 'blob of grease' test. It also drives fine with no huge holes in the power curve.
Blob of grease test. I need to remember that one.

I don't know why the 3.6 does but it does. Really, believe me. I don't want to have to break out the video camera but I will if need be. :D

Actually, I don't want anyone to see how dirty my engine is.
 
#20 · (Edited)
I don't DOUBT you, I just don't see how it can as it isn't electrically driven. We are talking about the same part here, aren't we? Standing on the right side on the car it's on top of the inlet manifold with the vac line to it, you can move the flap arm forward and back with your finger. That one?
 
#21 ·
I believe the 3.6 is driven by a standard protocol whereas the 3.8 is driven by the DME and only actuated between certain parameters: Full throttle and below engine rpm (circa) 4100 and above 6200, where it 'fattens up' the torque/bhp. (Not a technical man, but this is how I understand it?)

Maybe Rob Levinson can help us out on this one?

TIA Rob

Regards

BC



London Mike said:
I don't DOUBT you, I just don't see how it can as it isn't electrically driven. We are talking about the same part here, aren't we? Satnding on the right side on the car it's on top of the inlet manifold with the vac line to it, you can move the flap arm forward and back with your finger. That one?
 
#22 · (Edited)
I also concur that on the 3.6 cars the resonance flag cycles on ignition 2, the 3.8 cars do not.

The highly advanced "blob of grease" method of testing the system whilst the car is driving and under load, replaced the old "trained gerbil" in 1992 when a new Euro-law came in to protect them. Shampoo in the eyes; no problem. A nice drive around the countryside; banned!!


Ivan.
 
#23 ·
I tried the blob of grease method to confirm that flap is not working.

As per my first post, treid changing the ECU from a 3.6 which has it working, changed the solenoid, changed the actual thing that opens the flap.......nothing makes it work.

I've even changed the fitst bit of pipe that goes to the inlet manifold but that didnt make any difference either. Don't want to go to a garage and pay them mega bucks, so what should I do now?

Also, does the resonator flap stay in its current position upto approx 4000 rpm? Is it top end when it changes shape and gives more power? Because the car just doesnt have the "boost" effect at top end.

I'm\sure someone has a good idea here.
 
#24 ·
After my post above, I purchased a new actuator for my 3.8; the 'blob of grease' test didn't work. It still didn't work after I had changed the actuator. I then ordered various bits of 'hose' to replace hose that may have been worn.

Hose arrives; I remove intake plenum as I can't get my hand into the space to replace the hose to the acutator from the electric valve. This hose turns out to be fine, but I replace it anyway; however; there is another hose which connects to this valve which is not connected!! I reconnect it and 'hey presto!' everything works again (actuator and 'blob of grease' test).

I'm going to remove the plenum again and replace as much hose as I can see; when I ordered the replacement hose from BMW, they supplied me with around 2m length and a similar amount of the 'spiral' outer protection stuff. I also ordered the 'elbow' connectors and the 'T' connectors in anticipation.

As I had to remove the MAF to Plenum hose (the big one) I also decided to replace the MAF screens on either side of the housing. On inspection the one on the air filter side was broken and all the mesh wires were hanging loose. url: http://bmwe34m5.com/faqs/?theme=1&l...43&chapitre_id_select=37&document_id_select=3

Please be advised that on the 3.8 engine the air filter side grille is bigger than the plenum side grille. With retainer they cost about £7 per side; needless to say I have a spare air filter side grille and retainer.

Still think my 'throttles' need balancing; have oversize pistons after engine overhaul, which may impact the throttle balancing? any ideas as to how sensitive this department may be? Most welcome?


Regards

Brian




Cyrus said:
I tried the blob of grease method to confirm that flap is not working.

As per my first post, treid changing the ECU from a 3.6 which has it working, changed the solenoid, changed the actual thing that opens the flap.......nothing makes it work.

I've even changed the fitst bit of pipe that goes to the inlet manifold but that didnt make any difference either. Don't want to go to a garage and pay them mega bucks, so what should I do now?

Also, does the resonator flap stay in its current position upto approx 4000 rpm? Is it top end when it changes shape and gives more power? Because the car just doesnt have the "boost" effect at top end.

I'm\sure someone has a good idea here.
 
#25 ·
Thanks for that.


I will remove the plenum and take a good look.

I did actually remove a plenum on my first car and ran into a problem. The bottom of the plenum fixes into something like a bracket, how do u remove this properly?
Also, are there are vacuum hoses I need to be aware of?
 
#26 ·
Check out this website under 'Technical Articles': Last item shows how to remove the plenum. File was to big to 'attach' sorry?

But .............. there are two 13mm nuts either side of the bottom most hose, which reside in a support bracket attached to the engine. Best to remove the BIG hose between MAF and Plenun first. It is fiddly but quite easy, but time consuming.

let me know if you need any help?

Cheers

Brian



Cyrus said:
Thanks for that.


I will remove the plenum and take a good look.

I did actually remove a plenum on my first car and ran into a problem. The bottom of the plenum fixes into something like a bracket, how do u remove this properly?
Also, are there are vacuum hoses I need to be aware of?
 
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