[mrd5477]

Hi,

Had a DPF light flash up a few weeks back, most likely caused by more local trips since COVID.

I had the DPF chemically cleaned on the car. It turned out to be pretty blocked with the exhaust back pressure way higher than it should and explains why the power was down, the car was a bit smokey and smelling very sooty.
The clean brought everything back down to normal and the car was running well...but within a couple of weeks (<400 miles) the DPF light is back and symptoms are reappearing...and I have done a couple of long/motorway journeys in that time too.

Using the BimmerLink app I can see I have several errors, some related to the DPF, others I am not sure about.

A6D1: ADDITIONAL WATER PUMP
480A: 480A particulate filter system
4D00: 4D00 exhaust back pressure sensor, signal
481A: 481A particulate filter system
4DFF: 4DFF swirl flap actuator, position control
4E09: 4E09 swirl flap, plausibility
4010: 4010 Exhaust back pressure sensor in front of particulate filter, signal
9CB2: LWR potentiometer defective

I know the DPF errors needs to be cleared before it can regen and I have tried this through the Bimmerlink app. For a few seconds after clearing, the app says a regen has been requested and is running, but then it quickly stops when the error reappears. I can't seem to keep the error away for long enough for it to complete the regen. Any ideas?
Could any of the other errors also be preventing a regen?
Also, the fact that the problem has reappeared so quickly makes me concerned there is another underlying problem with the car that is causing soot to build up so quickly.

Coolant temp is 91deg, half tank of fuel and I have also tried replacing the DPF sensor in case that was dodgy (no luck).

Car is pretty old 2008 (E91) 320d with 177k miles.

Any thoughts are welcome.

[Tambohamilton]

A6d1, 9cb2; ignore for now.
4d00, 4010; I think these are your main issue. Looks like the pressure sensor in your DPF (before it, not after) is defective. Or potentially a wiring/plumbing issue.
4dff, 4e09; do you have swirl flaps still? Is the actuator/pressure converter plugged in correctly? Not sure if these errors will prevent a regen, but they will definitely affect the amount of soot being produced.

[mrd5477]

Thanks for the reply.
I had the back pressure errors both before and after changing the DPF sensor, which would suggest to me it's not a sensor issue...unless I've had two bad ones. I think it is the sensor before (it's one like this: https://www.buycarparts.co.uk/febi-bilstein/8008343)

I do have swirl flaps (unless they were removed prior to me buying the car 10 years ago)

If I have located the actuator/pressure converter correctly (at the front of the engine see photo) then the connections all look OK. I did spot that the plastic casing for one of the wires has been damaged/corroded. A quick tug on the wire inside suggests it is still connected

[Tambohamilton]

Someone correct me if I'm wrong here, but there should be 2 wires going to that pressure converter?

That definitely looks like the correct pressure sensor, but I'm starting to have doubts of whether that's a cause or symptom.

Have you checked your thermostat function?

[Andystobbs]

No converter or else needed for swirl flaps. Its purely electrical, given all the goo in that area its probably leaking gunge where the arm goes into the manifold. It may even be seized up solid. Might as well remove the swirl flap actuator to see if it is trying to move.

481A will prevent a regen, it is too blocked to be deemed safe.

[Tambohamilton]

Whats the one with the dodgy wire on the front of the engine for? Engine mounts?

[Andystobbs]

Can't remember exactly but I think that's lower down on the side or rear, when fitted.
That up front is EGR valve or cooler bypass I think.

Soon find out by unplugging it and seeing if another fault crops up.

[mrd5477]

I'm planning on removing the swirl flap actuator this weekend to get a better look...and maybe even the whole intake manifold if I have to.

I had a closer look in that area with the car idling...clearly, there is a lot of oil and goo there so the swirl flap error looks justified!

When I looked at the small gap between the actuator and manifold I spotted what looked like the swirl rod spinning. Is that expected?
See video: https://photos.app.goo.gl/B4iNpiTp7w2AgFfG7

From a few videos I have seen about swirl flaps, I had expected the rod to just rock back and forth only when the swirl flaps opened/closed.

I have been able to press and move the arm on the actuator itself and it returns back to its original position when I let go...some resistance but it felt like it was from the motor rather than a physical obstruction. When I turned off the car I did get a buzzing sound from that area for 10+ seconds...no idea if that is a normal part of the car powering down?

edit: I forgot to say, I think it may have (partially at least) regenerated on Wednesday evening. My app suggested regen was running and the performance greatly improved afterwards...the app still says I have high levels of soot and slightly elevated back pressure, but there's definitely less smoke out the exhaust.

[mrd5477]

Further update...I took the swirl flap actuator off today. There is LOADS of oil behind it.

The actuator seems to work OK and the arm was in place, but it looks like the lug on the end of the swirl flap rod that it connects to is broken. Also, there is a shed load of play in the rod itself.

new photos & video added to google album:
https://photos.app.goo.gl/B4iNpiTp7w2AgFfG7

I am hoping that the gap that's there from all the play is where all the oil is coming from and that if I can replace the intake manifold it will solve the problem. I'm going to try and find a second hand/recon manifold to keep the cost down. Are there any other components you'd suggest changing at the same time?

My main worry is whether there should there be oil (and this much) in the intake manifold...would it (again) suggest another underlying problem that also needs resolving first?..and that by replacing the manifold I am just masking something else for a while?

TIA

[Tambohamilton]

Yeah, that swirl flap rod looks a mess! From what I see there though, the gunk is nothing noteworthy; EGR soot mixed with the normal fine oil mist from the turbo makes a horrid tarry nonsense which gets forced out of every possible orifice.

I think you're on the right track to replace the manifold, though I'm sure others would recommend deleting the swirl flaps entirely. I don't know what the right solution is for replacing the manifold though... Clearly a new OE part would be ideal, but they're £££! Everything else is something of an unknown quantity.

I would start with replacing the manifold. Clearly it's in bad shape and the swirl flaps have not been working properly; this could be enough to cause the rest of your problems. While you've got the manifold off, definitely clean as much carbon buildup as you can from the ports etc etc - that would also be a contributing factor for poor running and DPF clogging. Search 'CBU cleaning' on the forum and you should get a heap of info.