Air mass filter or inlet manifold cleaning

Thank you for opening this and apologies as this is a long question.

My 5 year old X3 2.0 diesel has had a long problem with the engine warning light coming on. Originally the garage cleaned/blew air into the air mass filter which cured the problem for a while (conveniently to get it through the warranty period). It persisited and eventually I had the air mass filter changed a few months ago. Again the problem went away and drove really weel, but after 3 days the light appeared again and ever since the consumption has dropped to ~25mpg from a reasonable 35mpg in general use and on the long run from 50-60mpg to ~40mpg if I am lucky.

The garage says the inlet maniflold may need cleaning as that is all they can think the problem is.

Welcome your views...is this a common problem?

Also, is this something I can do....I am not averse to working on the engine myself. Many years ago I was a dab hand at re-building VW beetle engines....not done that sort if thing for 30 years now....if so how?

Any advise or suggestions welcome

Cheers

You would have to drive in some pretty dirty, dusty conditions to muck up your intake system. Hopefully you are not driving your D in those types of conditions.

Sounds like a dirty intake should not be a cause. A mass flow meter not reading correctly could possibly cause fuel/air ratios to be off, burning less efficiently.

I can read my air mass flow on my Garmin ECOROUTE, even though I would not have a clue what it is supposed to read, but if it was off you may be able to determine if that is the problem, especially since you had a history of this already.

If you have access to a decent shop perhaps they could check the air flow reading for you?

Have not seen where this has been a problem on this side of the pond.

Thanks Flyingman,

I intend to take it into the local BMW service shop.

The way it was explained to me by the garage was that the air mass sensor reads the flow of air going into the chambers and then decides the amount of flue to inject. They think that becaue the exhaust air is burned again and passes through the inlet manifold this has caused a build up of "crud" which is disturbing the flow.

Not sure if this right so welcome any views.

Cheers again

I was not sure if our engines recycle some of the exhaust back into the intake. Normally that is not a good idea. Bad air/fuel ratio means too rich with fuel, incomplete burning, etc...

If there is build up I would suspect it would be on the exhaust side unless you had some bad valve overlap and exhaust was coming back out the intake, highly unlikely with a turbocharged engine.

Your model and engine should be a pretty popular one over there, unlike what we are faced with here, so you should be able to get some competent service.

Good luck and let us know how it turns out.

Balzep, sent you a pm.

Originally Posted by Flyingman

I was not sure if our engines recycle some of the exhaust back into the intake. Normally that is not a good idea. Bad air/fuel ratio means too rich with fuel, incomplete burning, etc...

All our engines (and the UK ones, too) use EGR (Exhaust Gas Recirculation) to help reduce NOx emissions. The "Introduction to diesel technology" and "ST180" pdf files talk about this. The shiny metal square can on the front of our 335d engines is the EGR cooler.

The US engines have a slightly different setup for EGR than the UK ones; my guess is that the separator and valve have failed somewhat and are allowing coking on the intake valves, or buildup on the intake manifold. I think that a walnut-shell blast cleaning of the manifold and valves is probably the type of repair needed.

Originally Posted by floydarogers

All our engines (and the UK ones, too) use EGR (Exhaust Gas Recirculation) to help reduce NOx emissions. The "Introduction to diesel technology" and "ST180" pdf files talk about this. The shiny metal square can on the front of our 335d engines is the EGR cooler.

The US engines have a slightly different setup for EGR than the UK ones; my guess is that the separator and valve have failed somewhat and are allowing coking on the intake valves, or buildup on the intake manifold. I think that a walnut-shell blast cleaning of the manifold and valves is probably the type of repair needed.

And EGR's on diesels in my experience are notorious with "mucking up" the intake system. I had a failed EGR on the truck and the end result was the entire intake system had to be pulled and cleaned out, was not pretty at all.

Someone on here posted up about their 2009 335d recently needing a software update for what I thought they said was carbon buildup in the intake system.

Based on doing some quick research I would have to agree that the EGR could very well be a culprit of your problem.

I had completely forgotten about those. We would never reintroduce gasses of combustion back into our large Power Generation Engines. Wreaks (sp?) havoc on the entire intake system and causes lots of cold corrosion, etc...

Read up on it here: http://www.automedia.com/Exhaust_Gas...cr20060101eg/1

I had the same issue with my 02 MCS and had somewhat like K&N filter and messed up the MASS flow sensor, I finally got rid of the filter and started using the AMSOIL EA filter made from microfiber, which needs cleaning every so often by using a vaccum cleaner, and I never did have anymore problems of such matter