hqstu

e39 m5 carbon build up

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Hello,

Has anyone any experiences / information on the potential issue of carbon build up in e39 M5 engines?  In both the secondary air system and in general?  I've been reading it can be a problem on US Spec LHD cars, but unsure as to Euro spec RHD's (ours).  Also related to fuel quality and how often the big jandel is utilized... more nana driving accelerates carbon build up?

Has this caused any problems here and solution?

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I think the only carbon buildup really you need to worried about is on your spark plugs.... maaaaybe valve seats but would have to run fairly rich for that to happen.

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@BreakMyWindow will probably know if it's an issue or not.

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It is definitely a US spec LHD issue  and it's worse than the Volkswagen diesel scandal. BMW left out the Correolus  Flux Corrector to improve fuel consumption figures because when they were doing their engine design they forgot that American gallons are smaller than imperial gallons so the actual fuel consumption during road tests was appalling .

The Correolus Flux Corrector  (CFC) is used to ensure the gas spirals the correct way down the exhaust, but it causes a slight increase in fuel consumption .

Right hand drive cars don't need the CFC because the extra weight on the right side of the car means the gas spirals the correct way any way.

Also it doesn't affect southern hemisphere car because Correolus effect spirals the other way down here.

You can also improve the CFC behaviour by carrying 3 bags of cement in the right front seat of a US LHD BMW - this counteracts the driver mass and predisposes the exhaust gas to spiral the correct way.

 

 

Edited by 3pedals
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It would be fantastic if all your posts were that complete, accurate and helpful Ron. 

Could I do it on the cheap without the weight by just using shorter springs on the LHS? 

 

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I forgot to add that they usually fit two CFC's for cars destined for the American market, the reason being for each CFC you fit you can reduce the  fuel "RON"  (not my big brother or related to me) by 5 points so an M5 which should be run on 98 can run on 93 with one CFC.

If you add a second then you can use 88 RON and if you go for the full Quad CFC set up you can run an M5 on 78 RON which is essentially kerosene, and I suspect that is the issue here. The problems of sooting up are caused by owners running their M5's on kerosene and not having the required quota of Correlus Flux Correctors.

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7 minutes ago, M3AN said:

 

Could I do it on the cheap without the weight by just using shorter springs on the LHS? 

 

Yes you could but it is easier to adjust the correction with cement bags especially if you let you 50lb trophy wife drive on  occasions - although in this instance I believe the usual requirement is also to add a further 9 bags in the boot so she can't drive it faster than you can.

And the shorter springs would need to be on the right

Edited by 3pedals

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All e39 m5's get the secondary air circuit in the heads blocked up with carbon. This triggers a fault code called : 'Minimum flow of secondary air' Google search it and you will see what happens and how to fix it. This does not affect performance so I wouldn't worry.

Edit, some light reading : http://www.m5board.com/vbulletin/e39-m5-e52-z8-discussion/128129-secondary-air-system-carbon-build-up-removal-pictures.html

The exhaust valves can get carbon build up which will affect performance but that is rare and i think is created by short drives and lots of idling.

Edited by BreakMyWindow
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Wow, fascinating... there's a whole different world out there...

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Some more reliable information from the "Turner" website.

The problem is that carbon builds up in the passageways for the air pump system. Carbon is a by-product of the engine's combustion. But this issue is different than the normal carbon build-up from inside the combustion chamber. Normally, the carbon exits the engine with the other exhaust gases through the manifolds, cats, and out the tailpipe. However, normal backpressure in the exhaust forces some carbon back into the cylinder head and into the air pump system where it settles and hardens. There is a shut-off valve that is designed to prevent exhaust from re-entering the system but this valve can become faulty over time and with no warning. Eventually each passageway and air port becomes clogged and blocked, as much as 100%.

 

For the level of carbon build-up to occur as shown in the images "M5 board"  post there would need to be some other very fundamentally wrong elements contributing to the situation, the most fundamental being the owner.

 

 

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Yep, no one should own or drive one as they will block up the inheritantly flawed secondary air emissions system..

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Air injection systems were introduced in the mid 60's as a means to reduce emissions, with modern engines these tend only to be used during the cold start phase.

Like any system on a modern engine they need maintenance, specifically ensuring they are working and periodic replacement of the non return valves and is a good starting point.

If your car has such a system and you are not sure of its' condition - get it checked and if you plan to keep the car do some Preventative Maintenance on it.

Rash claims of the epic failure   of these systems can be found relating to  Audi, BMW, Porsche Volkswagen etc.  or basically any manufacturer who employs such a system. The reality is the system is only as good as the operator and in this case that is the car owner.

Audi, BMW, Porsche and Volkswagen have no control over the .01% of retards that buy their cars and don't maintain them, then whine all over the internet  about fatally or inherently  flawed designs.  

How many whines are there about PCV systems yet people continue to use sh*t oil, skip services and then complain about engines sludging up ??

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17 hours ago, BreakMyWindow said:

Whilst I understand that's an extreme example it's a fascinating read, thanks.

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4 hours ago, 3pedals said:

Air injection systems were introduced in the mid 60's as a means to reduce emissions, with modern engines these tend only to be used during the cold start phase.

Like any system on a modern engine they need maintenance, specifically ensuring they are working and periodic replacement of the non return valves and is a good starting point.

If your car has such a system and you are not sure of its' condition - get it checked and if you plan to keep the car do some Preventative Maintenance on it.

Rash claims of the epic failure   of these systems can be found relating to  Audi, BMW, Porsche Volkswagen etc.  or basically any manufacturer who employs such a system. The reality is the system is only as good as the operator and in this case that is the car owner.

Audi, BMW, Porsche and Volkswagen have no control over the .01% of retards that buy their cars and don't maintain them, then whine all over the internet  about fatally or inherently  flawed designs.  

How many whines are there about PCV systems yet people continue to use sh*t oil, skip services and then complain about engines sludging up ??

There are plenty of inherently flawed designs in the automotive industry Ronald. No one really gives a sh*t about one which only affects cold-start emissions. If this issue did affect the engine in terms of engine performance then it would be a different story.

 

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Dave it is a fascinating read , but  when you read further through the associated posts the underlying reasons for the problem finally surface. the actual article does not identify these.

And if you only read the article you might reasonably conclude that the Air injection systems are "problematic" where in fact they are quite reliable but not capable of reversing the astounding stupidity of some owners and their mechanics - both would need to play a part in the outcome  for that vehicle.

What we need to remember is the query from the Op "is it an issue here?" - answer it will be for some vehicles but is it a design/ functional  failing - NO.  

 

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Yeah, I read quite a few pages in and I'm not personally interested in what causes it, rather than it can happen at all. Since many of these will not be with the original owner it seems it would be difficult for prospective or new owners to know if they have the 'problem' or not.

Unless the owner's manual actually tells you how to mitigate this then it's my opinion that you can't blame the owners/drivers because if they're only doing what they're told to do...? If they're using the highest grade of fuel available to them and driving it like a nana are they really doing anything the dealer/manual said they can't? Or not doing something they were told they should? My M3 manual certainly doesn't say take it to redline frequently but many advocate doing so. e36 M3's (and e39 M5's?) were sold new in NZ before the recommended 98 RON was available meaning 95 was the best available.

I'm not arguing with you Ron, just sharing my thoughts, and I have no opinion on the merits of other opinions expressed herein but I respect Martin's knowledge of e39 M5's.

 

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I recall Dads E30 manual saying something along the lines of: if you've done a lot of town/low speed driving, to take it on the highway and use a gear or two lower for a while :lol:.

It sounded like a PC/Professional way of telling you to give it a gentle italian tuneup.

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1 hour ago, M3AN said:

Yeah, I read quite a few pages in and I'm not personally interested in what causes it, rather than it can happen at all. Since many of these will not be with the original owner it seems it would be difficult for prospective or new owners to know if they have the 'problem' or not.

Unless the owner's manual actually tells you how to mitigate this then it's my opinion that you can't blame the owners/drivers because if they're only doing what they're told to do...?

 

So that's where we differ , in my day job it is often about finding the root cause of a  problem  during an investigation and  the forensics can be  the fun bit. But more importantly you can get some objective learning from it - which is what we are looking for.

IMO if you take this approach then you can identify the probability of various issues being likely to occur, having done that you can then decide whether you can remedy or should do some P.M to mitigate the risk of them occurring.

Case in point my Saab - sh*t maintenance by previous owner of 6 years clogged PCV system  meant it was spewing oil -  so I researched the issues assessed the risks  and then bought it cheap and then went through the PCV system and did a flush and 3 oil changes in quick succession - it now makes it through an oil interval with clean oil and doesn't spray oil everywhere. .

I could take the other approach and just buy mechanical insurance - but IMO that is a blunt instrument  and a poorly serviced car is a time bomb.

 

Your second comment quoted is  a moot point- the owners manual does not lay out a preventative maintenance schedule - this comes from the service side of the business BMW and dealers. An example here is the filled for life transmission fluid.

Those of us that change diff and transmission fluids at 100,000km intervals are  less likely to have diff and transmission issues all other things being equal -- we could stick our heads in the sand and say but the manual doesn't say we should do it so we won't OR we could say this could be a sensible, low cost preventative maintenance (P.M) measure.

 

It's just a different approach but my experience has been that I get a much longer service life from my vehicles than average. You will also find the larger high value fleet owners and major equipment operators use a similar approach

Red-lining a car is just that - it is not a P.M strategy.

 

Edited by 3pedals

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I'm sure your approach is better than mine Ron, thanks for letting me know.

/threadparticipation.

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Comments were made as a sincere contribution - no need for a snarky comment.

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