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Huh, the usual scenario i have seen is some other code actually trips the SES light, like a misfire, and the AA code is stored.
So you've seen an SES light and the only fault code was AA?
 

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I read post 36. I understand what you are saying but my opinion is this... The secondary air passage being block and causing an SES will lead to further carbon build up on valves and in the chambers.

Let me put it another way... Has anyone experienced these excessive carbon conditions without the secondary air system failure or SES? I know what the secondary air system is for and how it works. I believe failure of this system definitely leads to excessive carbon build up which will undoubtedly effect performance.

I agree it is a design flaw etc. I just do not see the facts of excessive carbon build up with a working secondary air system.

Ryan

On post #36 of this thread you'll see some pix from a tear-down of one of our members' engine w/ ~100k mi. The BMW techs who inspected the engine said that the tear-down presented a normal, well maintained engine with the exception of carbon-blocked SAS passages. The owner of this car had S2 upgrades, used the best gas, and 'drove the car as intended'. The owner obtained agreement from BMWNA for a goodwill repair.

The evidence we have indicates that if we were to tear down a bunch of engines with the SAS carbon problem we'd find combustion chamber carbon build up ranging from nasty, to 'normal'. This would indicate that the SAS problem is not related to customer upkeep issues as BMW would have us believe. Rather, the issue is caused by a design weakness that makes the SAS passages suseptible to a chronic carbon deposition process that is surprisingly unaffected by the obvious variables (oil consumption, driving habits, gas used, etc).

Here is the carbon build up poll from a couple of years ago. Data were collected from 20+ members with the carbon problem.

http://www.m5board.com/vbulletin/e39-m5-e52-z8-discussion/58145-poll-carbon-build-up-issue-all-members-please-read.html

<O:pHere is my analysis of the poll results.
</O:p<O:p</O:p
http://www.m5board.com/vbulletin/e39-m5-e52-z8-discussion/63737-carbon-build-up-issue-survey-results.html

I have the letters challenging BMWNA on this issue that I can post if interested.

Dave
 

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Water meth is a great tool. It would probably help greatly. The problem is this... On a N/A car you need to be able to make huge timing adjustments which is not possible unless you can get your DME custom tuned and or you switch to stand alone engine management.

Ryan

Has anyone got any practical experience in water injection with our beasts? At least I would expect that there are 8 injection nozzles required to ensure even mix in every cylinder. Either they would have to be fitted in the butterfly assembly or below the intake trumpets within the air intake box.
 

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I read post 36. I understand what you are saying but my opinion is this... The secondary air passage being block and causing an SES will lead to further carbon build up on valves and in the chambers.

Let me put it another way... Has anyone experienced these excessive carbon conditions without the secondary air system failure or SES? I know what the secondary air system is for and how it works. I believe failure of this system definitely leads to excessive carbon build up which will undoubtedly effect performance.

I agree it is a design flaw etc. I just do not see the facts of excessive carbon build up with a working secondary air system.

Ryan
Guess I'm not sure what would be the basis for accelerated carbon build up if the little smog ports behind the exhaust valves become occluded. With clogged smog ports, the S62 is just like any other engine (without the flawed SAS design). Baby it, you'll get more carbon. Run it hard, you'll probably see a cleaner combustion chamber.

Now, if someone is unconcerned about their M5 and running Walmart gas, never exercising her, etc. I suspect we'd see an acceleration of all types of carbon, including SAS buildup. The design flaw is that the SAS is not robust to intended use, good gas, and normal maintenance.

Dave
 

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Water meth is a great tool. It would probably help greatly. The problem is this... On a N/A car you need to be able to make huge timing adjustments which is not possible unless you can get your DME custom tuned and or you switch to stand alone engine management.

Ryan
Ok Ryan. Do you think the huge timing adjustments are needed with water-methanol only in the US or also elsewhere?
 

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?? OBDII trouble Codes ???

This board has been such a helpful tool for me over the years and it is about time I become a member and start to post. First, I have a question about a 2002 M5 in my shop that is throwing 3 codes a dmtl code, a coolant temp sensor implausable code, and a secondary air pump quanity too low code. I am concerned that this car has the carbon problem. Exactly what codes are thrown in the DME to identify the carbon problem. Any technical information with this would be greatly appreciated.
 

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Dumb question time, so forgive me. I have always read that carbon buildup had no effect on performance. Only throwing codes and causing some to not pass emissions.

Take this from a guy who doesn't look inside engines very often, but you are telling me that all that gunk in there has no affect on the performance/longevity of the engine at all?

Why would anyone in their right mind pay to have it fixed when they could get the PC software? I say this as I am getting AA codes right now, that I have never had before and my beast has 140,000 miles on it, so its of more concern to me now.
 

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codes

the only codes i can see that have been stored were the AA Quantity too low code and the coolant temp sensor code (69) brought from my autologic. i have read other threads about thermostats not going into closed loop and throwing air codes beacuse of the mixture and such but i replaced that today. the car reaches above 79deg. and after the 3 drive cycles the light turns right back on. I will say i am a little new to the E39 M5 carbon problem so any information will help.
 

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Dumb question time, so forgive me. I have always read that carbon buildup had no effect on performance. Only throwing codes and causing some to not pass emissions.

Take this from a guy who doesn't look inside engines very often, but you are telling me that all that gunk in there has no affect on the performance/longevity of the engine at all?

Why would anyone in their right mind pay to have it fixed when they could get the PC software? I say this as I am getting AA codes right now, that I have never had before and my beast has 140,000 miles on it, so its of more concern to me now.
The carbon build up in the intake, combusion chambers and exhaust of this engine are dramatic... but none of that is the "Carbon Buildup" in the secondary air passages that causes the dreaded AA code. Two different build ups-

I'd rather have a car without it- like I'd rather have a car without high oil consumption...but if I every get the AA, it is powerchip time.

A
 

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great post and nice pictures thanks for this job and we need more look likes this post but
how many mileage it done or what kind of oil and fuel it use.....................its realy scary views
 

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I still wonder if the fact that most of our cars burn 1+ quart of oil per 1000 miles doesn't have more to do with this than the fuel. This motor looks just like the insides of the passages of a rotary Mazda motor (which by the way injects oil directly into the combustion chamber)

Just a hunch.....

RR

PS do you know the oil consumption on this motor?? and thanks so much for the info!!!
I've maintained this for a long time. I'm not an expert, and I'm not even a college graduate. However, those cars that are consuming oil are burning it, and one of the byproducts of oil burning is soot, correct? That soot has to go somewhere, and I'm convinced that this is where it's going.
 

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From the carbon build up survey three years ago (my how time flies), I saw no difference in mileage of onset of the SAS CBU problem and whether the cars were original ring design or updated ring design. The oil consumption of original ring design cars averaged about 1L/1000 mi and the updated ring design averaged about 1L/2000 mi. This relationship held even after omitting one or two outlier data points.

It was a surprising result. I was expecting to see a relationship, but couldn't find one.

Dave
 

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Thank you for pulling this thread up Mert... I had forgotten what a great photo montage you put together on the secondary air system/carbon build up removal!

For those of you who haven't seen this, take a look....:rolleyes:

Dave
 

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We've talked about cleaning up the carbon build up now lets talk about prevention. The air plenum is designed to carry in plenty of oil through the oil separators/ crankcase. There are other ports from the plenum that potentially brings in oil. How about blocking all ports that carry oil to the plenum/throttle bodies and then vent the crankcase to the atmosphere.....ok it is not pollution compliant but it can save the engine long term ?
 

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mert5,

out of curiosity is it possible to have both heads removed with engine still in the car or does the engine have to be removed in order for heads to be taken off? The TIS instructs engine to be removed. Not sure why:sad3:

BTW - my car has a code related to the secondary air. Now that I decided to go ahead and replace the timing chain guides/rails I was going to remove both heads and clean the secondary air passages as well. It would be the best if done all at once, right?
 

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mert5,

out of curiosity is it possible to have both heads removed with engine still in the car or does the engine have to be removed in order for heads to be taken off? The TIS instructs engine to be removed. Not sure why:sad3:

BTW - my car has a code related to the secondary air. Now that I decided to go ahead and replace the timing chain guides/rails I was going to remove both heads and clean the secondary air passages as well. It would be the best if done all at once, right?
Unless you are doing this yourself as a hobby or personal challenge, I would just have the DME programmed to ignore low secondary airflow.

Whatever caused your problem to begin with will likely cause it to recur..

A
 
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