[command_liner]

Is it possible to get the DPF into a condition where it can never regen?

I am wondering if this is what started my series of problems. Our 335d is used locally and never gets up to operating temp, like for a month at a time.
So there is never a regen, at least that I can tell.

Clearly there are faults in the design of the 335d emissions systems. The CBU does not happen on any well-designed system. Could it be possible that there is another fault, one where months of short-distance low-power driving loads up the DPF so much that it is never possible for the regen to happen because the car no longer can make enough power to run hot and long enough to run a regen?

I call this a 'trap' because once you fall into this mode, there is no way out, save with a replacement of the DPF.

If there is not a software hook to deal with this series of real-world driving conditions, then I consider this a bug, and an emissions fault.

What do you think?

[Hoooper]

I dont know if the car will let you get to that point or not, but if you assumed there were no protections against it then yes absolutely. However, I think you will get DPF codes before reaching that point.

[command_liner]

As the days go by, I am developing a theory.

The programming/design of the car does not accommodate or deal with CBU.
Since there is "no CBU", under the driving conditions we had (short cold trips with no highway use for 40 days at a time) DPF regen never happens.

On both the intake and the exhaust side, flow gradually goes down, down,
down. The computer adjusts.

Then CBU is done. Intake flow goes way up, injectors are radically unbalanced and begin rebalance.

The DPF is now, in effect, plugged, especially relative to the intake. The "plausibility" tests now all fail, and the car persists in limp mode. Regen can never succeed because there is never enough flow to work the engine hard enough to get it hot enough for regen.

Customer gets large bill to fix this bug.

[335dwanted]

I tend to agree with Hoooper; if the DPF becomes so clogged that it can't regen (there is good evidence that this does happen) the car will almost certainly throw a DPF code.

For what it is worth, the car does not need to be driven at highway speeds to regen, it can and does regen in city driving as well; I think the only real requirements are coolant temperature and fuel level. Certainly highway regens are quicker and perhaps even more effective (but I have no evidence of that).

If you do want to see when regens are happening as well as determining when the last regen happened and frequency of regens, you can use the BMWhat application (you will also need their Bluetooth OBD adapter).

It seems that DPF problems are more prevalent in Europe and I have seen very few DPF problems on this side of the pond across this and the other forum. My car has a relative short frequency for Regens (read from BMWhat app and verified by my tracking since I took ownership in August) of 270 miles. In researching the issue (trying to decide if I should use a DPF cleaner fuel additive) I found a couple of threads from Europe with persistent DPF regen problems but these were always indicated by DPF SES codes. Link below is one of those threads.

http://www.e90post.com/forums/showthread.php?t=651679

An interesting aside is that DPF cleaner fuel additives are quite common in Europe but I cannot find one supplier here in the states. I appreciate that there are a whole lot more diesels in Europe, but there must be more to it than that. Maybe our fuel is better but I find that a bit hard to believe. My bet is that our DDEs are programmed differently somehow. Perhaps this is evidence of Command Liners theory that the DPFs clog but don't throw codes.

[dixy2k]

Have you monitored the car parameters during your daily drive?

[335dwanted]

Originally Posted by dixy2k

Have you monitored the car parameters during your daily drive?

I use Torque most of the times that I drive and I display Coolant Temp, Exhaust Temp and a handful of other parameters. Torque does not display the DPF specific parameters that BMWhat can provide, but I much prefer Torque display to BMWhat. With Torque I have an audible alarm that sounds when exhaust temps go over 950F indicating regen and then I hit the trip meter when regen finishes so I can track the regen frequency.

Both apps can log data from various parameters if you want to download it.

I have been meaning to watch the DPF parameters during driving such as accumulated soot (or ash, I can't remember the name) but have not gotten around to it.

[dixy2k]

My question was for the OP. Trying to find out how does he know there is no regen.

[command_liner]

I do not have the car now, the dealer has it.

The dealer gives the DPF plugged diagnosis, but that was my thought
too. When I did not tighten the band clamp on the ERG, there was
very clearly high exhaust pressure. I would say in the 20-30 PSI
range, venting out the EGR. That means the pressure in the manifold
had to be at least that much.

The dealer ran a more complete diagnosis than I can and came up with
overpressure/DPF plugged. This comports with my experience of no boost.
If the exhaust cannot flow, no boost can be produced.

After a good long discussion, the service manager agrees there may be a bug here. The CBU is a bug in the system -- software or hardware. The DPF plugging would be 'past the event horizon' of the CBU, which should never
happen. I spoke with BMWNA about possibly finding a bug in the emissions software. They were useless, unresponsive, generally dumb and slow. Quite a disappointment.

There is one DPF in the western US, and only 6 available in the whole country. I expect to get the one in Stockton picked up and sent here for install. This is covered by the CARB 7/70 warranty, but only if the standard diagnostic process finds the problem to be a plugged DPF.

Confirmation of DPF plug after CBU clean requires a full rebalance of the injectors. The dealer wants to charge $500 for this work. Seems high.
What do you guys pay for injector rebalance?

[command_liner]

I do not *know* there are no regens, but the driving situation would not permit regens. The commute is only 5 miles, and the car hardly warms up.

The dealership, not the smartest guys, did not snapshot the the state of the car when we brought it in the first time. Valuable information was not preserved at any of the service events.

[335dwanted]

My guess is they are going to reflash the DDE. See this thread for a description:

http://www.e90post.com/forums/showth...=calibrate+dde

$500 does not seem a bad price, but I think it should be included with the replacement of the DPF under warranty.

[dixy2k]

$500 is an excellent price to pay to have everything back in order.
I can refer to my local dealer for a special price since they know me there very well.
It will cost you more though, like a downpayment a new car.

[command_liner]

Originally Posted by dixy2k

$500 is an excellent price to pay to have everything back in order.
I can refer to my local dealer for a special price since they know me there very well.
It will cost you more though, like a downpayment a new car.

The car has 63,163 miles on it and was under BMW care for the first 60,000 miles of that. The CBU happened, the boost hose leaked a few gallons of oil, the DPF plugged and the radio died 10x.

Now the dealer wants me to pay $1000 to help them check out a component that is covered under the 7/70 CARB emissions warranty. This has been dragging out for 7 weeks and I have no loaner.

My take is that the car should not have had major failures at 60K miles, and the dealer should not ask me to spot them $1K so they can diagnose warranty items. Oh, and give me a loaner when you are looking at warranty items.


The car is great when it runs. I would buy another "sick" one for $10K and fix the emissions system by relocating most of it to the shelf and adding another cat to burn off as much soot as possible. Then the car would be both reliable and fun to drive.

[dixy2k]

It's BMW, of course it will have failures at 60k miles.