Diesel hypermileing

[JCL]

Originally Posted by diesaroo

Removing the DPF and other emissions hardware (EGR) might not be "environmentally friendly" or legal, but it does simplify things and theoretically will reduce the amount of possible engine failure modes down the line.

I don't agree that removing the DPF and emissions hardware would simplify things. Building an engine without them in the first place, would, yes. But that isn't possible. These engines have integrated engine management strategies, you can't just remove a system and not expect the engine management system to notice. I think that butchering the software will provide additional failure modes, and add risk beyond any theoretical reliability improvements due to removal of hardware.

The EPA was very concerned that if they allowed diesels with urea, owners would tamper with them and nullify the emissions controls. It delayed the introduction of clean diesels by several years. As a result, there are tamper indicators built in, since the manufacturer had to provide assurance that the controls would still function for 100,000 miles.

I think it would be funny if someone did remove hardware, and was tested in a few years and failed. I have never re-installed emissions controls on a diesel, but I did it years back on customer gasoline-fueled vehicles that had the emissions controls removed, and subsequently failed tests. Very expensive for the owners.

[diesaroo]

Originally Posted by JCL

I don't agree that removing the DPF and emissions hardware would simplify things. Building an engine without them in the first place, would, yes. But that isn't possible. These engines have integrated engine management strategies, you can't just remove a system and not expect the engine management system to notice. I think that butchering the software will provide additional failure modes, and add risk beyond any theoretical reliability improvements due to removal of hardware.

The EPA was very concerned that if they allowed diesels with urea, owners would tamper with them and nullify the emissions controls. It delayed the introduction of clean diesels by several years. As a result, there are tamper indicators built in, since the manufacturer had to provide assurance that the controls would still function for 100,000 miles.

I think it would be funny if someone did remove hardware, and was tested in a few years and failed. I have never re-installed emissions controls on a diesel, but I did it years back on customer gasoline-fueled vehicles that had the emissions controls removed, and subsequently failed tests. Very expensive for the owners.

Exactly, any modification would have to be well engineered and the programming would have to seamlessly integrate with what the BMW ECU wants. In other words, the computer would be "collecting data" as it always has, and as long as the perceived values are within spec, the ECU would be happy.

It remains to be seen as to whether any additional longevity could be obtained by the streamlining of the emissions system, but past experience tells me it would. Perhaps you are not aware of past failures in the diesel emissions design department. Ever heard of the problems MBZ had with oxidation traps? Granted that was years ago, but it is similar in concept to DPF.

I really don’t mind the urea, since this is simply an after-treatment device. I think the worst thing is the EGR. The manufacturers have tried to mitigate some of its issues, but it remains a problem nonetheless. Most high mileage diesel owners will deal with a failing EGR valve sooner or later. The M57 engine has 2! It is a bad concept from an engine wear point of view. Instead of releasing a little soot into the atmosphere, it concentrates in the engine oil and gums up the intake valves. Soot accumulations can be so bad that in the previous generation M57 engine, the intake swirl flaps get stuck and break off into the engine causing catastrophic engine failure. At least in this generation of the M57, BMW was smart enough to use all plastic intake swirl flaps, so that they can be ingested by the engine and burned up without CEF.
And since there is a DPF to boot, the additive package in the approved engine oil (LL-04) is pretty weak since any conventional strong anti-wear additives cannot be used without clogging up the DPF. It is also well known that the DPF is not really maintenance free even though it regenerates itself. The DPF will have to be either replaced or backflushed eventually to the tune of a couple grand.
I’ll give you another problem: do a quick search of the UK X5 forums and you will find that when there is a turbocharger failure, all the oil that the failed turbo “pukes” into the exhaust will promptly destroy your DPF and SCR catalyst. I can’t imagine what the bill for that trio of failures would be…
So yes, there is some risk to modifying the emissions system, both legal and technical, but there is also a good deal if you do nothing at all.
Of course, this is of interest only to those who keep their cars past warranty period.

[JCL]

I think that the risk of modifying an E70 diesel to remove emissions controls is greater than the potential benefits, largely due to the integrated nature of the controls. These aren't like an early Powerstroke or Cummins 5.9, where a straight pipe solved the DPF replacement cost problem.

I do agree that as this generation of diesels ages, owners are going to be faced with costs that they likely didn't expect. New diesel owners traditionally think about not requiring tune-ups, no spark plugs, etc, and think that their engines will therefore have a lower cost to operate than a comparable gasoline engine. Since there is no longer any significant tune-up cost on a BMW gasoline engine, I think those costs are a wash. What does cost money is complexity, and BMW poured a lot of it into the new clean diesels to make them clean. Those parts will be expensive post-warranty.

I also agree that it makes no sense to be planning this now for a US market diesel under a four year warranty. Tampering with it just means agreeing to pay any emission system repair costs that BMW would have otherwise paid under warranty. This tangent started with the suggestion that GoVol's mileage could be improved by removing the DPF and reprogramming the DDE.