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Discussion Starter #1 (Edited)
ATTN: Any members who have an aftermarket exhaust system. More specifically, one with reduced back pressure. Even more specific, DINAN Exhaust + DINAN Mid Pipe (X-Pipe).

Effect: M5 no longer idles steady.


Anybody else have this issue?


Thanks in advance..
 

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This happened to me when I had my RDsport system (headers, race cats, x-pipe, exhaust) but it was around the same time I was having an issue with the Singh tune. When I switched to the RPI system, Eloy thought that I might have had an exhaust leak. Once I had the RPI system on and new ESS tune, the idle problem went away. I'm not sure if it was the exhaust or the old Singh tune.
 

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When did you feel the unsteady idle? Immediately after installing exhaust, or later on?
 

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I wanted to get some opinions from more experieced M5 and M6 owners then I, as I've only had my 2007 M6 for a few months and thought you might have some advise to offer me. I'm interested in improving the sound and of course power from my M6 and want a deeper more aggresive sound from my car without making it too loud. There are so many options I've become lost in the search. There are three that come to mind, but I'm not sure which if any is the best muffers and or exhaust that suites my needs. I'm considering Dinan, Eisenmann and Evosport street not race systems. Are ther any published horsepower or torque gains available for these systems? Any advise or thoughts on which manufacturer has the best product would be greatly appreciated!

I personally don't have any experience with any idling problems, but my friends 2009 M6 with Dinan exhaust runs great. I will check around more here in CA with the Dinan folks and see what I can find out for you.

Thanks, Fred from San Jose CA
 

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I wanted to get some opinions from more experieced M5 and M6 owners then I, as I've only had my 2007 M6 for a few months and thought you might have some advise to offer me. I'm interested in improving the sound and of course power from my M6 and want a deeper more aggresive sound from my car without making it too loud. There are so many options I've become lost in the search. There are three that come to mind, but I'm not sure which if any is the best muffers and or exhaust that suites my needs. I'm considering Dinan, Eisenmann and Evosport street not race systems. Are ther any published horsepower or torque gains available for these systems? Any advise or thoughts on which manufacturer has the best product would be greatly appreciated!

I personally don't have any experience with any idling problems, but my friends 2009 M6 with Dinan exhaust runs great. I will check around more here in CA with the Dinan folks and see what I can find out for you.

Thanks, Fred from San Jose CA
You probably don't want to hijack avInch's thread so I'll keep this short but you'll want to also consider RPI which has proven/dyno'd power gains: YouTube - BMW M6 by RPI: M6BOARD.com. Search on this board for more info.


Back to avInch's question, I don't think I have had a problem with mine (full RPI system). I have noticed every once in a long while that at idle, the tone on my exhaust sometimes hops around (goes from low, to high, back to low in a span of a few seconds). But when this happens, my RPM needle does not move at all so I think it's just the exhaust hitting some resonance frequencies from time to time as opposed to a steady idle issue for me.
 

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According to the software version you have on the car, the ECU will manage the cat's heating differently. On many versions, when the temp of the cat drop below a certain level, the ECU raises the idle rpm slightly for a moment to heat them again, and once done goes back to normal.
Problem when this happens: with an aftermarket exhaust it gets very very noisy then. With my ASR it was just similar to cold start noise.
Second and bigger problem: as the exhaust have a very low back pressure the cats cool down quicker/sooner, and even raising the idle rpm, the ECU is unable to heat them again, for example in a traffic jam or long lights. So what happens? well you have cold start noise constantly and need to tap your ears and fellow motorists around have to do so as well.
Hope with the Dinan the effect is not so bad.
I had my car updated to the latest software a few weeks ago, and this behaviour has disappeared, idle steady at 750rpm :) :)
Maybe you should try an update?
 

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I think this is a cold start issue like Cool Cat said. Mine does this only when it's a cold start. once the car is warmed up, it's smooth as buttah. I have the RPI section 3 only.
 

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Discussion Starter #9
This happened to me when I had my RDsport system (headers, race cats, x-pipe, exhaust) but it was around the same time I was having an issue with the Singh tune. When I switched to the RPI system, Eloy thought that I might have had an exhaust leak. Once I had the RPI system on and new ESS tune, the idle problem went away. I'm not sure if it was the exhaust or the old Singh tune.
Yes, the ESS software corrects this problem. ESS raises warm idle, therefore eliminating the problem. So with the car idling at 900RPM, it is as steady as can be. However, at 850RPM the problem still exists.
When did you feel the unsteady idle? Immediately after installing exhaust, or later on?
My '08 M5 had this problem slightly with DINAN Exhaust. My '10 M5 now has this problem, but worse and I have DINAN Exhaust + X-Pipe. Also, the Brilliant White M5 with DINAN Exhaust + X-Pipe (same as me but he has 3.5" res and I have 4" res) has the same problem.. but his was not as bad as mine was. Again, weird part is - when raising the idle to 900, problem disappears.
I wanted to get some opinions from more experieced M5 and M6 owners then I, as I've only had my 2007 M6 for a few months and thought you might have some advise to offer me. I'm interested in improving the sound and of course power from my M6 and want a deeper more aggresive sound from my car without making it too loud. There are so many options I've become lost in the search. There are three that come to mind, but I'm not sure which if any is the best muffers and or exhaust that suites my needs. I'm considering Dinan, Eisenmann and Evosport street not race systems. Are ther any published horsepower or torque gains available for these systems? Any advise or thoughts on which manufacturer has the best product would be greatly appreciated!

I personally don't have any experience with any idling problems, but my friends 2009 M6 with Dinan exhaust runs great. I will check around more here in CA with the Dinan folks and see what I can find out for you.

Thanks, Fred from San Jose CA
Unrelated, but honestly the way to go is to get the DINAN Exhaust. It will make the car sound much more aggressive without being too loud. RPI is also good, but I personally do not have experience with them. I believe RPI is louder than DINAN, but do no take my word for that.
According to the software version you have on the car, the ECU will manage the cat's heating differently. On many versions, when the temp of the cat drop below a certain level, the ECU raises the idle rpm slightly for a moment to heat them again, and once done goes back to normal.
Problem when this happens: with an aftermarket exhaust it gets very very noisy then. With my ASR it was just similar to cold start noise.
Second and bigger problem: as the exhaust have a very low back pressure the cats cool down quicker/sooner, and even raising the idle rpm, the ECU is unable to heat them again, for example in a traffic jam or long lights. So what happens? well you have cold start noise constantly and need to tap your ears and fellow motorists around have to do so as well.
Hope with the Dinan the effect is not so bad.
I had my car updated to the latest software a few weeks ago, and this behaviour has disappeared, idle steady at 750rpm :) :)
Maybe you should try an update?
That makes perfect sense. I don't think there is any software out for the 2010MY though.
I think this is a cold start issue like Cool Cat said. Mine does this only when it's a cold start. once the car is warmed up, it's smooth as buttah. I have the RPI section 3 only.
My car did not idle correct during both, Cold Start & Warm Start.
 

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Yes, the ESS software corrects this problem. ESS raises warm idle, therefore eliminating the problem. So with the car idling at 900RPM, it is as steady as can be. However, at 850RPM the problem still exists.
I thought about this too but not sure if that's the case. I had Jags from Singh Autosport try to address the problem and he tried a different tune then what was on my car but it didn't help. It could just be that my RDSport exhaust developed a leak somewhere over the 2 years or so that I had it and once the new RPI system came in, it was fine. Just speculation of course.
 

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Well, I can definitely say that during the cold months of Dec and Jan, my car's cold start was very very rough! Almost felt like the car was gonna die due to initial idle fluctuation.

I can safely say that since filling her up with high octane fuel, that problem has gone away and she revs up right from the start and goes through her normal warming up process!

Bad gas, bad injectors.. these could all cause rough idle during start up!
 
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