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Ok not that i want to debunk anyones theory about solving this issue but i just found out my thermostat is Fxxked. And to be honest guys, I was going to sugest this from the start being that 95% of the the time this is a text book symptom. But i kept my moith shut being that im a newb with BMW but some of the suggestions iv seen regrading this issue are completely fauls.
And if ya wondering did he even reset the adaptations? Yes i did and it done nothing. And this whole warmig the cats up WTF. Thats true they do need to be warmed up but in no way in hell will it trigger Your car go back into a cold start.
 

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Do someone know if CATALYST Adaption reset - Is this possible on M5 E39 (I have same problem) ? - I don't remember seeing this function in INPA.
 

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As iv written before first thing you need to check is your engine temp
If your well below 90deg Celsius then you definitely have a thermostat issue and most likely it is.


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Don't confuse cold start with a "hot" high idle.

In a cold start situation, the secondary air pump is working to pump fresh air into the exhaust tracts. This is very obvious as the car sounds like it has a straight-flow exhaust mod (even if you just have 100% stock exhaust system). And initial idle will be in the region of 1000-1200rpm. And the tacho redline will be around 6800rpm. Then as engine warms up , tach redline will slowly climb up to 8200 and if you have a OBD logger, that's when water temp reading is >82~84 C.

A "hot" high idle happens when the engine is already nicely warm-up, but it doesn't have that loud exhaust noise symptom. It's just that the engine is idling higher than usual & that is the issue being addressed here. Just to clarify, this is NOT a cold-start scenario (re)happening.

As for thermo problems, if you have a Thermo monitoring error (as read from GT1/DIS/INPA/ISTA/aftermarket tools , but it doesn't prompt any warnings on the iDrive screen ) , its not a big deal (thermo stuck in open position), just that the engine will take longer than usual to fully warm up. But once it warms up, the loud exhaust noise goes away just the same and idle will be nice at 750-780rpm.




E39 : no idea.
 

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Ok not that i want to debunk anyones theory about solving this issue but i just found out my thermostat is Fxxked. And to be honest guys, I was going to sugest this from the start being that 95% of the the time this is a text book symptom. But i kept my moith shut being that im a newb with BMW but some of the suggestions iv seen regrading this issue are completely fauls.
And if ya wondering did he even reset the adaptations? Yes i did and it done nothing. And this whole warmig the cats up WTF. Thats true they do need to be warmed up but in no way in hell will it trigger Your car go back into a cold start.

Well, i know my erratic high idle was caused by CATALYST adaptation values. Can't say the same for you though. Maybe (?) you have a leaky vacuum somewhere thats leaking more air into the intake plenums and hence beyond the idle circuit's control in keeping the revs low ? Of course you can determine this for sure if you have a leaky vacuum by looking at the "Excess Air" adaptation values and see if they're thrown off. Maybe your DME have an overeager compensation for the idle torque value? Many different causes for similar symptoms.

As for a Bad thermo that's stuck open, no dice. I had this too, and changed it, and it didnt do jack for the high idle even when engine is fully warmed up. The engine DID reach operating temperature sooner though (and saved a few pennies on gasoline there) but that's it.
 

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My problem is a stuck thermo or even a broken seal. engine temps well below 90deg
Iv had this problem many times in Audi’s Honda’s all sorts. If your car is not at optimal temp it will do what’s needed to warm it up.
 

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Yeah but even with a stuck open thermo, the car would still eventually warm up enough to reach operating temp, and if in spite of this the engine still wants to idle fast, then something else is provoking the DME (ECU) to idle fast.


Interesting you brought up Honda as an example. Honda’s idle control mechanisms (PR3, P30, P73 ECUs in particular are my ex-poisons) are almost quite radically different from how a MSS65 ECU for the S85 controls idle.
 

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I had same problem high rpm on idle when hot, nearly all time 900-1100. As advised i deleted catalyst adaptations and all went back to normal 750 all the time when hot. Adaptation were 0.84 and 1.48 after delete and 400 miles adaptations now 0.1 and 0.1 . ISTA says max value 1.1 in USA and 1.0 Europe also it says if values above max catalyst test should be run. I tried to run this test on ISTA and DIS with no luck, test never ends and not giving any results for some unknown reason( maybe i have to delete lambda adapt as well to balance system). Now im not sure why those values was so high in first place? Due to bad cats or something else? At first I decided to FAM tune and go catless , now after 400 miles of trouble free idle I probably leave as it is. That was cheapest fix so far.
 

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I had same problem high rpm on idle when hot, nearly all time 900-1100. As advised i deleted catalyst adaptations and all went back to normal 750 all the time when hot. Adaptation were 0.84 and 1.48 after delete and 400 miles adaptations now 0.1 and 0.1 . ISTA says max value 1.1 in USA and 1.0 Europe also it says if values above max catalyst test should be run. I tried to run this test on ISTA and DIS with no luck, test never ends and not giving any results for some unknown reason( maybe i have to delete lambda adapt as well to balance system). Now im not sure why those values was so high in first place? Due to bad cats or something else? At first I decided to FAM tune and go catless , now after 400 miles of trouble free idle I probably leave as it is. That was cheapest fix so far.
Awesome fix bro! Deleting cat adaptations seems to be the trick. I too had no idea how mine climbed up to 0.4'ish previously but after 1+K km's, it seems to be holding at 0.1 still. And no more crazy high hot idle at 1K rpms too.
 

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What would would cause a high catalytic converter adaptation value?
I’m getting a value of 1.14 in bank 2 but bank 1 is reading 0.56?

Reset it 3 times and comes back after a few drives


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just to add on this topic...

I had high RPM on idle(900rpm). The way the car as behaving was ..whenever I was coming to a full stop... the rpm would drop at 700(normal) for about 3,4 seconds and then climbing to 900rpm and just staying there. I have also noticed that after my trips the car was super hot..much hotter than usual....another thing I noticed was that, at idle, the coolant temp would raise to 90,91C on and decrease when increasing the rpm(to 80C-85C)
Now the strange part, resetting the cats adaptation used to fix it but just for about 50 miles and then again, the same problem. Ran cats tests in ISTA-D and all came good
The other day, when i was inspecting the engine, i noticed a coolant leak just by the thermostat and when i checked the coolant level i found it to be below minimum. I need to add 1L of coolant to bring the level to normal.
(shame on me, i dont know how i missed to check the coolant level for about 6 months).
1000 miles later, no high rpm issue and the car dont feel as hot as before adding the coolant.
I cannot explain why clearing the cats adaptation temporary fixed the high rpm at idle........but the culprit was deffo low coolant.
 
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