35i exhaust doesn't pop so much now days

B

bazzae123

Member
 Cambridgeshire
Hi Guy's,

I wondered if this in normal. I have a 2010 35i that used to make me smile with all the pops and wheezes but recently Ive noticed it doesn't do it as often or as loud as it used to, unless I'm getting deaf.
I had the car remapped over 2 years ago and it's now on 40K. I checked the Vacuum flag today and that appears to be in working order, closed during warm-up and then open after a sort period of time, so that doesn't appear to be the problem. I did start to think that the original popping was caused, some how, by the turbo and maybe that's on its way out.
I was thinking of popping it back onto a dyno and see if the power is still there, or dropping it into a independent for them to give the car a health check.

Has anybody heard of this issue before, or experienced it, and is there anything I should check first?

Any advice would be greatly appreciated.

Bazza
 
Hi guy's,

Quick update. I noticed this morning that the exhaust flap closed when I first started the car but after a short drive it was still closed even though the engine was warm so that may be the reason why the car sounds different, the flap must be getting stuck closed. After I stopped and checked the flap I manually forced it open but again after a sort drive it appeared to be closed again, strange. Perhaps the vacuum isn't being released!
Anyway, there's an update.

Bazza
 
oli445 said:
Sounds like you have found the problem, let us know how you get on fixing it :thumbsup:
Click to expand...

I hope so. I want that throaty sound back, and of cause those lovely pops :D not sure at what price though! lol

Bazza
 
No other issues such as increased fuel consumption or anything else?
 
Hi Guy's

I really confused now. Been ready a bit on line and there appears to be two trains of thought on the subject of whether the flap is open all the time or not.
Some people are saying its only closed during the first few minutes from start up, just to warm up the Cats a bit quicker and also to reduce noise and then it stays open. Others are saying it's dynamic and varies its position according to driving styles, hard acceleration for instance will open it. It closes when the car is stationary to reduce noise in the cabin for passenger comfort and so on.

Now, with mine, it closes when I start the car from cold. After driving until the engine is warm I check and mine is still closed. I can manually open it again by hand and hear the difference in exhaust note but as soon as I drive away I can hear the exhaust note drop again, rechecking the flap and it's closed itself again.
Also, and I'm not sure if it's just me, but I would say the power is slightly down as well, more like the pre-map. oh, and I checked fuel consumption and the on board still shows the same usage.

If anybody has a 35i can you check for me if the flap on yours always appears closed or not. Just look at the flap and if its fully retracted, lever pointing up, then its closed.

bazza
 
My 35is is very loud on start up as both flaps on mines are opened but it should be that it's closed until you 'give it some beans' and then the other flap opens up increasing the noise level. I think it sounds like it's sticking shut for some reason as you initially expected. I can't think that the 35i would be any different from 35is in terms of how the exhaust althought slightly different is supposed to work.

My car is so loud on start up it actually makes my other halfs R32 GTR with a very loud exhaust sound normal!
 
Bazza
IIRC flap closes via the vacuum pot on start up to reduce noise levels. Your described symptoms suggest it is remaining closed.
Why not try the Golf Tee mod? The flap will then be permanently open. If this restores the desired burble pop bang va va voom you have identified the problem. Unfortunately I believe it's an integral part of the rear exhaust section so it's a simple but expensive remedy.
If the flap is stuck closed it may need the actuating lever holding with eg a cable tie.

HTH
 
Hi Guy's,

Just to give you an update. The jury is still out regarding whether the flap is operating correctly or not, sometimes its open when I look and other times is closed LOL

I called BMW today and got the answer that it should be open all the time when driving. I then called an independent, who has worked on my other BMW's in the past, and they tell me its dynamic and only opens during certain loading conditions, ie. above 2500 revs when accelerating hard. So there we go too different theories of operation :headbang:
Anyway the independent will charge me £30 for a diagnostics report so I though I may as well get it looked at. I know this will only involve sticking some equipment on the car and reading fault reports etc but he has told me that they can check turbo pressure as well.
The reason for the check is I want to see if there is anything else causing a problem because when the flap is open I still don't appear to get that lovely burble and popping sound I used to get.

I'm going to call the guy's who mapped it now to see if the re-map would have caused the reduction in popping but I'm sure it was OK afterwards or I would have been worrying about it a long time ago, if that makes sense.

By the way. The only other thing that is going through my head is maybe it has something to do with the fuel I'm using!!! I used to use BP ultimate but now use Shell Nitro, may be that has something to do with it. I don't know I'm lost for answers :cry:

Anyway, I keep you informed on how I get on!

Bazza
 
Hi Guy's,

Just got time for an update. Had the car on a dyno the other week but that didn't show any issues, it was down circa 10HP from when it was first mapped but I understand that could be down to all sorts of reason so I wasn't that concerned.
Starting using BP fuel again, but that hasn't made any difference. One thing I did notice the other day though. The flap was closed still after a good run so while stopped at a level crossing I opened it manually. By the time Id got home ,which was another 5 minute drive, it had closed again. Therefore there must be a vacuum still present to cause it to close.
Anyway. I had to phone BMW and ask what may be going on. Still waiting for them to come back to me but Ill let you know how I get on.

Bazza
 
I was going to say it's not to do with the petrol. BP ultimate is not regarded as the best fuel as it's only 97 ron whilst Shell V Power is nearly 100 ron at 99.7 ron but marketed as 99 ron.

It's clearly an issue with the exhaust. The valve is electric so maybe that's knackered. The full valve with bracket is part number 18307586758 and the actual valve itself is 11747810831
 
Thanks for that :)

As you said, the fuel hasn't made a difference, but at least that's ticked of the list now. There's something strange going on though. I pulled the vacuum tube off this afternoon and it appeared that the flat was stuck closed as I had to give it a good pull to open it, and without the hose being on I would have expected it to open quite easily. And as I said in my previous post for some reason the flap closed the other day even with a hot engine and Id opened it manually only 3 miles before. I'll see if BMW phone me this week but it looks like I may have to get them to investigate :(

Bazza :driving:

Edit
I think the numbers are for the control mechanism and not the flap. The actual flap appears to be part of the exhaust end pipe as BMW decided to spot weld the bloody thing to it. Therefore, I think if you need a new flap you end up buying a new exhaust, part No 18307647050. It's the small round cylinder shown on the top pictured tail pipe end :thumbsdown:
 
Car booked into dealer next month for them to have a look to see if the flap is operating properly, that's the earliest they can do :headbang:

Now been told by them that the flap is dynamic and only operates under certain conditions. I bet I end paying for them to tell me it stuck closed sometimes lol
The guy I spoke to appeared to know what he was on about and some of the questions I put to him were answered as I had expected, after learning a bit or two about it anyway.

So, I'll let you know the outcome next month!

Bazza
 
Good luck. I'm sure they will find the problem, It shouldn't be closed all the time as suspected on yours
 
Hi Guy's,

Just got back from BMW £96 lighter :( The situation is the flap is getting stuck closed some of the time. I say some of the time because I believe once the exhaust is hot it frees up. I have looked at the flap after a good run and I can move it up and down quite easily. When it cools down it stiffens up again. Now BMW let me behind the scenes when the car was on the ramp and the guy put a external vacuum hose onto the actuator and showed me that the lever was trying to lift the flap but it appeared the actual flap is the problem and not the controlling vacuum cylinder(actuator) that sits on top of the exhaust.
Now, the real problem though was they couldn't get a control signal from the ECU to open the solenoid that allows the vacuum (from the engine) through to the actuator. So, they think its either the ECU has a problem, or the cable harness leading to the solenoid as well as the sticky flap :x . If anything, I think its the cable harness as the flap sometimes works the way it should and opens. Therefore it must be intermittent and that usually points to the cabling. Well, being an electronics engineer it could be a intermittent fault with the ECU but I want to put my money on the cable first LOL
So, there's two problems.

On the way home tonight, I decided to pull the hose of the actuator and leave the flap in an open position to see/hear if the popping and burbling returned now I can guarantee the flap is open. The car obviously sounded a bit more throaty but still no popping. I then rang the guys who re-mapped it and we have decided to put the original map back in as they think that they may have advanced the timing a bit to much and that's why I've lost all the nice pops and bangs. I cant really comment on that as ignition and so on is a bit over my head lol
So, the saga continues and I'll let you know what happens next! Hopefully I will be able to get the old map put back in tomorrow.
 
Hi guy's,

Last update on this subject.

I had the car in for another fault finding, after the initial one ran out of booked in time. The conclusion is a fault existed with the cable loom that prevented the vacuum solenoid (this is in the boot) from opening the flap. The second fault is the flap jams when the exhaust cools down, it moves OK when hot.

BMW say I need a new exhaust and solenoid, there fixed the cable loom while finding the fault as it was a loose connector.

Now for the good news. I had call from the garage and was told that BMW will replace these parts free of charge as a jester of good will, I will only have to pay for the fitting which equates to circa £300. The exhaust alone would have been over £1000, not including fitting.
As you can imagine I thrilled to bits with their decision :D
I'm not sure why they decided to do this but I'm not going to argue! :thumbsup:

Bazza
 
Nice result :D athough why this has to be a integral part of the exhaust for such a litte problem beats me and it seems to be quite common . :(
 
Good result.

Wish my local BMW dealer had one of those jester's of goodwill. :D

The joke is usually on me every time I walk out of the showroom.
 
Why don't you just keep the flap open all the time? It's such a waste to mute that nice rumble at startup!

When I had my HPFP replaced I noticed the exhaust sounded a lot angrier when leaving the dealership. It settled after a day of driving.
I think the nice burbles and pops are down to unburned fuel igniting in the exhaust. With the HPFP replacement they reset the engine adaptations which I think causes the engine to over-fuel slightly until it relearns.

I have since manually reset the throttle adaptations myself using INPA and noticed exactly the same Increase in exhaust pops for a couple of journeys.

I think a remap of the DME will change your exhaust characteristics as the boost pressure and fuelling of the engine has been changed. I think the ignition timing is also adjusted.


What you want is an anti-lag system fitted to your car. Then you can have all the pops you ever dreamt of :evil:
[youtube]lckXqMU50J4#t=21[/youtube]
 
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