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Danish, I understand your thinking on this subject. But, as I understand it (and, I should emphasize, I don't know for sure), the European model M5s do NOT use the same system we use in the US.

I just hope someone on this board who is a chemist (and, understands how carbon forms and condenses), AND who is an automobile engine guru would help us out in trying to figure out what actually causes this build up to happen.
 

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I was idly thinking... would maintaining positive pressure to the secondary system- ie running it with some kind of fresh air input 100% of the time- prevent fouling?

I suspect that it is fuel and oil laden air going 'backwards' into these air passages that causes the problem.

This might be a 'solution' and not a 'mask, con, repair, etc'...

A
 

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I was idly thinking... would maintaining positive pressure to the secondary system- ie running it with some kind of fresh air input 100% of the time- prevent fouling?

I suspect that it is fuel and oil laden air going 'backwards' into these air passages that causes the problem.

This might be a 'solution' and not a 'mask, con, repair, etc'...

A
I think that is a good idea, too, Adam. It seems to me that with the Secondary Air pump ON, the air moves through those small holes near the valves and out through the exhaust system, and the pump pressure doesn't let anyting IN. But, with the pump OFF, it is an invitation for the exhaust to go BACK through those small holes and "maybe" gum things up. Leaving the pump on (and using up some horsepower to drive the pump) may reduce the "pollution."

Just a thought.
 

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something to look foward to when I pick up an M5!

I bet it was a Lease turn in that some poor guy picked up. The Leasee most likely used the cheapest gas around town, not to mention it probably wasn't even 91 octane!

Danish, I understand your thinking on this subject. But, as I understand it (and, I should emphasize, I don't know for sure), the European model M5s do NOT use the same system we use in the US.

I just hope someone on this board who is a chemist (and, understands how carbon forms and condenses), AND who is an automobile engine guru would help us out in trying to figure out what actually causes this build up to happen.
Do the euro M5's even have this problem? I would think this was done with the US spec engines to accommodate US emissions regulations and thus only plaguing the US M5's.

:dunno:
 

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I think that is a good idea, too, Adam. It seems to me that with the Secondary Air pump ON, the air moves through those small holes near the valves and out through the exhaust system, and the pump pressure doesn't let anyting IN. But, with the pump OFF, it is an invitation for the exhaust to go BACK through those small holes and "maybe" gum things up. Leaving the pump on (and using up some horsepower to drive the pump) may reduce the "pollution."

Just a thought.
Unfortunately, the pump would quickly overheat and destroy itself. That particular pump is not of such design or duty cycle that it can run longer than in "spurts"
 

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Unfortunately, the pump would quickly overheat and destroy itself. That particular pump is not of such design or duty cycle that it can run longer than in "spurts"
Agree. Plus that much air into the exhaust/cats would be a problem.... I was just thinking a positive ventilation- just enough to overcome exhaust leaking into the passages.
 

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Sorry, I would expect a better air pump with what I was pondering. One that would last.

IIRC, some cars came with airpumps that ran full time, before cats were introduced.
 

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Sorry, I would expect a better air pump with what I was pondering. One that would last.

IIRC, some cars came with airpumps that ran full time, before cats were introduced.
Perhaps some cat-friendly type solvent (Seafoam?) could be blasted through the passages from the pump back every 20k miles? Something that carbon would be soluble in, etc...

Also, yeah, air injection was popular back in the mid-70's before we had 3-way cats. It was one of the first things to go on my '76 Capri as the pump was a huge parasitic drag on the motor.
 

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Danish, I understand your thinking on this subject. But, as I understand it (and, I should emphasize, I don't know for sure), the European model M5s do NOT use the same system we use in the US.n.
the euro s62's DO have the exact same system as our cars, same heads, same ports, same eventual clogging. BUT, their dme does not monitor for secondary air flow, they do not have the same level of obd2 as we do.

THat is how the powerchip 'work around' works, they make our dme not monitor it as well. I asked powerchip about this, they compared our dme to a euro dme and that is how their software patch came to be.
 

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Perhaps some cat-friendly type solvent (Seafoam?) could be blasted through the passages from the pump back every 20k miles? Something that carbon would be soluble in, etc...

Also, yeah, air injection was popular back in the mid-70's before we had 3-way cats. It was one of the first things to go on my '76 Capri as the pump was a huge parasitic drag on the motor.
I'm not sure carbon is soluble in anything, but like I said, we need a chemistry guy to confirm.

And, I, too, remember the drag on the engine with those early systems.

(And, my Mom had a Carpi as well ... :M5thumbs: )
 

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(And, my Mom had a Carpi as well ... :M5thumbs: )
:applause: ...though probably not one with stiffened, lowered suspension with solid delrin bushings, and a built higher compression V6 with Isky race cam, Offy dual plane manifold, Holley 4bbl carb, headers, etc. :hihi: The car was, in retrospect, kind of a junky design, but it was fun at the time chasing down Porsches and 70's Vettes and such.
 

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:applause: ...though probably not one with stiffened, lowered suspension with solid delrin bushings, and a built higher compression V6 with Isky race cam, Offy dual plane manifold, Holley 4bbl carb, headers, etc. :hihi: The car was, in retrospect, kind of a junky design, but it was fun at the time chasing down Porsches and 70's Vettes and such.
Touche, CSBM5 ...

No, you got me there, but I will say I that I thought the Capri wasn't a bad looking design, was about the right size, and it was fun to drive (it had a stick shift), albeit kinda crappy inside. And, I wouldn't have picked the color she had ... Metalic Green.

John.
 

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Discussion Starter #73
Mark, the 540 DOES succumb to the same problem. As I said elsewhere, it is my belief that the problem is not as prevelent on the 540, but it does happen to the 4.4 as it happened to mine. If it is related to oil usage then I am a little surprised my 540 has the problem since it uses no oil whatsoever. Neither does my M5 (knocking on wood now). The 540s do get the same problem- obviously Mert's expert opinion would be great at this point on the "Why did this happen, to this car, to this extent?" If it is oil comsumption-related, then the fact that more M5s use oil might explain it? Mert, jump in at any point now that we know what the problem entails, give us the "How" and to what engines?

Bill
According to BMW, "Excessive combustion chamber/exhaust manifold deposits may be attributed to usage of fuels with inadequate level of detergents. BMW recommends exclusive use TOP TIER Gasoline to prevent an excessive deposit build-up".

Models affected:

E38 (7 series), E39 (5 series), E53 (X5), and Z8 with the M62TU or S62 Engine.

the info is coming from service bulletin SI B11 05 04.
 

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According to BMW, "Excessive combustion chamber/exhaust manifold deposits may be attributed to usage of fuels with inadequate level of detergents. BMW recommends exclusive use TOP TIER Gasoline to prevent an excessive deposit build-up".

Models affected:

E38 (7 series), E39 (5 series), E53 (X5), and Z8 with the M62TU or S62 Engine.

the info is coming from service bulletin SI B11 05 04.
We've discussed this for a while.

The opinion is that BMW is covering an engineering fault. Plenty of evidence of failures in cars that ran 'top tier' gas. (And a legal theory that a manufacturer must design a product to run in local conditions)

Why does "non top tier" gas only behave badly in certain models? Point is that it isn't the gas, it's the engine!
 

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Why does "non top tier" gas only behave badly in certain models? Point is that it isn't the gas, it's the engine!
This reminds me of 1986. However, the issue then was somewhat different in that BMW had a big issue with drivability due to severe buildup of intake valve deposits and injector clogging. They blamed it on the gas here in the US (which was true to a great extent). This is the time when Techron came onto the scene and BMW got behind it. BMWNA implemented a program to "fix" every car where an owner complained of the problems (no matter if in warranty or not). They would even pull the intake manifold (this was on the M30 inline 6 motor) and attach this device that would blast the intake valve with walnut shells to clean off all of the deposits.

BMWNA spent a huge amount of money to "stand behind their product" back then. I had a good friend with a 1982 733i with almost 100k miles on it, and he was blown away that BMW blasted the intake valves clean, replaced all the plug wires and spark plugs and cleaned all the injectors all for free. His car ran great afterward, and he was a customer for life (sadly, he passed away in 1997). It paid off for BMW just a few years later when he bought a 1989 535i.

The situation with this current issue is probably that the number of occurrences of this problem has not (and probably will not) reach "that" level where a company like BMW opens up their pocketbook to cover the cost to the consumer across the board. It's clearly a business decision, and for those of us who have been in on those decisions in big corporations, you know the drill....
 

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So is the proactive, permanent solution like this:

1. Pull, strip, and clean heads.
2. Weld secondary air holes behind exhaust valves, and then port and polish.
3. Get PC chip fix to ignore subsequent secondary air complaints, as welded up holes/lack of flow may trip the SES.

Granted, this would do nothing about the source of the carbon - the combustion chamber - but it would isolate the secondary air system into irrelevance permanently.

Steve
00 M5
 

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So is the proactive, permanent solution like this:

1. Pull, strip, and clean heads.
2. Weld secondary air holes behind exhaust valves, and then port and polish.
3. Get PC chip fix to ignore subsequent secondary air complaints, as welded up holes/lack of flow may trip the SES.

Granted, this would do nothing about the source of the carbon - the combustion chamber - but it would isolate the secondary air system into irrelevance permanently.

Steve
00 M5
You could also do periodic induction flushes, run a tank of 100+ octane (unleaded of course) from time to time, and make sure to drive the car hard enough to blow all the carbon out :M5launch:
 

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Not hijacking, but have a question along the same lines. My car was shipped from the factory to British Columbia. It looks like it was driven there for maybe 19,000 miles and then was imported into the US. Car check shows this clearly. My question is WHY would my car have an SAP system at all? I was sooooo hoping that it was not there, but it was!
I doubt it was modified at 19K for shipment into the USA as it would have required a lot of parts plus ECU change, etc. Any ideas?

Bill
 

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Point is that it isn't the gas, it's the engine!
The situation with this current issue is probably that the number of occurrences of this problem has not (and probably will not) reach "that" level where a company like BMW opens up their pocketbook to cover the cost to the consumer across the board. It's clearly a business decision, and for those of us who have been in on those decisions in big corporations, you know the drill....
+1 to both. I still get requests now and then from owners with the problem looking for guidance on requesting a goodwill repair from BMWA. I share with them some recommendations and a letter template that has worked in the past, but caution that it could take some preserverance on their part to make it happen.

I continue to feel that BMWNA will step up to the plate on a case-by-case basis if the game is played right. However, with the $1000 PC patch, I suspect many feel it is not worth the time and effort (I never get follow ups).

Dave
 

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Not hijacking, but have a question along the same lines. My car was shipped from the factory to British Columbia. It looks like it was driven there for maybe 19,000 miles and then was imported into the US. Car check shows this clearly. My question is WHY would my car have an SAP system at all? I was sooooo hoping that it was not there, but it was!
I doubt it was modified at 19K for shipment into the USA as it would have required a lot of parts plus ECU change, etc. Any ideas?

Bill
Why would you think your car would not have the secondary air injection system.
ALL s62's have them, regardless of market, europe, canada, usa. They all have this system. The ONLY difference is cars in euro spec trim (i.e. not north america) do not monitor for the effectiveness of the system, so it can and will clog, but will not turn on an SES light. A code will be stored, however, but it does not trip the light in a euro car.
 
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