Hi
2008 Cooper S
A couple of weeks ago, I replaced the turbo oil line. In the process I put the car into radiator service mode. Everything went back together fine. Vehicle recently went thru emissions Ok.
Last week, I had a slight misfire/stumble at approx 3000 revs on acceleration. It happened again today and the engine light came on. Code is P115D and according to Bentley, "mass air flow rationality and range monitoring". I have cleaned the mass air flow sensor after the air cleaner and the one up on the passenger side prior to the inlet manifold.
I have yet to reset the code.
My issue is, under heavy accelerate, I am getting a whooping sound as the turbo kicks in which sounds to be coming from behind the bulkhead in the engine compartment.
I will be checking the hoses prior to and after the inter cooler just in case they were disturbed during the recent service position.
Any comments?

 

I meant to say, I cleaned the mass air flow sensor at the air filter exit. The other sensor I cleaned was the air duct pressure sensor on the passenger side. I have noticed that against the bulkhead is a "sound generator" that connects into the intake manifold air intake hose. What does this sound generator do? Could that be leaking ?

 

That is called the "noise maker". Many people remove it and cap the the line.

Do you still have the problem after cleaning the MAF?

 

Cerenkov, thanks, but was is it actually doing?. Removing/counteracting turbo whistle?.


I am still getting the stumbling/misfire under load around the 3000 rev/min.


The best I can explain it is: Running at 3000 rev/min, slight incline, accelerate hard. Turbo whoosh sound, engine stumbles/misfires, and the whoosh sound disappears. I have been backing off the throttle as I do not want to damage something. Car has 74000 miles on it. I am not sure if the Previous Owner had the inlet ports cleaned, or changed the plugs. A reminder, the fault code was for the mass air flow sensor (cleaned yesterday), which I still need to reset, hopefully today.

 

The noise maker generates noise to make is sound sportier.

 

whooping??????

diverter valve?:?

 

I have been doing a bit of digging on this forum, and think I may have found a possible cause. I have cleared the mass air flow code, engine light is off.
Again, 3000 rpm, going up a hill hit the accel, revs climb, I hear the bulkhead noise, (the noise generator?), sounds like air at high velocity, car stumbles, and then as if there was a blockage somewhere, power comes back with typical turbo power gain.
I am thinking it may be the vacuum hose to the waste gate actuator "collapsing" under the vacuum and then opening up again. The vacuum pump itself must be Ok as the brakes operate normally. There is also a "pressure converter" in the line that I presume is activated by the ecu to allow the vacuum to be applied to the waste gate actuator on the turbo.
If I accelerate such that the turbo spins up at a slower rate I do not get this stumble, so I am thinking a slow build up of the vacuum as opposed to a rapid change, prevents the vac hoses collapsing.

 

If your deverter valve is leaking it might be likely its only hold pressure at a gradual throttle and only show its weakness on moderate to high throttle since the vacuum builds faster. This is typically we see them act up, the rubber diagram typically tear and don't seal well under load. The deverter valve helps control vacuum in the intake, when you let off the throttle it opens up to allow the boost pressure to be relieved and once you're back on the throttle it closes to build boost.

I had a bad MAF sensor and after I cleaned it only then did it really start acting up, if you had a code for the MAF sensor odds are it's already bad unless cleaning it fixed your problems.

 

Thanks system lord. What do you mean by a diverter valve? What does it look like/part number/location in the car?
After cleaning and resetting the engine light/clearing the code, I have driven the car approx 30 miles, but did not accelerate at the rate that has been causing the stumble. Am away from home at the moment but will run the car when I get back.

 

The diverter valve is attached to the turbo. It is attached with three 5mm socket head cap screws (allen heads). It also has an electrical plug.

It's easy to remove and inspect for deterioration.

http://new.minimania.com/images_temp...1g2nme2225.jpg

 

Thanks Cerenkov. I checked out a couple of vids and replacement does not look too difficult, especially after my recent adventure replacing the crummy turbo oil supply line.If this unit is faulty, what is the best replacement?. I ain't no boy racer or doing track days. Reliability would be a bonus.

 

OEM is the best.

 

To make removal easy, get a 5mm hex key on a 1/4" socket. Make sure that it about 4" long.

Like this:

http://m.protoolwarehouse.com/prod-9...Fddahgod_ZAP_A

 

Ok back from trip. I have installed a scan gauge 2 so I can see the turbo boost figures. So here is what we have:
On highway, 3000 revs/min. Boost -7(psi). Floor the accelerator, whooshing sound from engine bay gets louder, boost goes to +3 psi. Car falters, boost drops to +1.8, sounds disappears and car continues to accel at +1.8 on the boost.
I repeated this 3 or 4 times with similar results. No engine light, so air mass flow sensor is Ok.
Car has 75000 miles on it, coolant temp 220F and battery voltage 14.0V.

Turbo diverter valve?

 

Get the revised diverter valve discussed here:

https://www.northamericanmotoring.co...e-upgrade.html

 

Thanks Cerenkov, is this part # 11658636606 referred to in the link compatible with my 2008 cooper S? In the link they mention 2013 N18.

 

I would think it would be good for all 2nd gen cars.

 

Maybe a busted dv?

 

This is 11658636606 which is the newest design diverter, also linked how to install.

https://www.northamericanmotoring.co...e-the-bov.html

 

OK. parts on order. Will keep you posted on the outcome. Thanks in advance.

 

Thanks and welcome.

 

Received the latest and greatest diverter valve and replaced the existing one. Existing one looked ok.
Took car for drive and still have issue, but the faltering is not as bad.
To repeat previous, 3000 rev/min, slight uphill, floor the accelerator, revs build, I hear the whooshing noise from the bulkhead(is this the noise generator?), boost now at 2.4 psi on the scan gauge, car stumbles,noise disappears, boost drops to 2.0 psi and car continues to accel. No code for air mass sensor fault.
Any idea what the max boost pressure with the latest diverter valve should be?

 

Stock max boost is approx 13 psi

 

Yes, and a little higher if you have a factory JCW.

I would check all the hoses and make sure the sound tube does not have a leak. The diaphragm on those can leak

https://www.northamericanmotoring.co...anifold-2.html

 

ECS Tuning:
The whooshing sound I hear is quite loud, and almost sounds like it is coming from the vent on the center top of dashboard. The "noise generator" sits in front of the bulkhead in approx. this position.
I am assuming the "noise generator" is the sound tube you mention, and is the large circular black object in the middle of your picture.
Is it normal to get this noise as the boost pressure goes from vacuum to pressure ?. Also, if this diaphragm is leaking, would it give the symptoms I am experiencing?. I will check all other hoses in the system over the weekend.