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S52 Bogging when cold; bad thermostat/ICV??
i have a 99 m coupe, just bought it with 33k. ran well, but about a week ago, i noticed a severe power loss when the --engine is cold-- under power. the engine lugs off stop signs and in 2nd... when normal operating temps are reached, it runs great. this is not the 'normal' bogging some road tests have complained about when launching from a stop. no engine light or any other indications. always maintenanced by BMW, meticulous though non-technical 1st owner (a friend). I have been told a possible thermostat or ICV is bad. I'd prefer to throw some cheap parts at it before going to the dealer... any help would be greatly appreciated... and, by the way, the car's sick. i don't care how fast 2006 cars are... this thing is the cat's pajamas.  | | Reply » S52 Bogging when cold; bad thermostat/ICV?? |
my M Roadster is always in limp mode when I start it in the morning, until the temp gauge reaches the normal mark, then it is fine...
it has been my experience that most high performance cars are this way
| | Reply » S52 Bogging when cold; bad thermostat/ICV?? |
This is normal, and I think you can take it in and they can fix it.
I just warm my car up like you should anyway.
| | Reply » S52 Bogging when cold; bad thermostat/ICV?? |
this is a dramatic power loss, though... like nearly stalling in the intersection outside my house as i pull into the roadway. i'll start out accelerating and literally fall against the seatbelt a bit under engine breaking.
car wasn't like this for the first couple thousand miles, as i remember.
my understanding is that a bad ICV or throttle control will manifest as a high idle or a really irregular fuel delivery ALL THE TIME.
and a bad thermostat seems to be a problem more when the engine is HOT, not when cold (i.e. they stick closed, not open).
i'm wondering if there's a fuel injection mapping thing going on BASED on the thermostat reading, though. i'm more of a motorcycle wrench than a car one, and i have heard about this on the BMW Kbikes before.
Thoughts?
| | Reply » S52 Bogging when cold; bad thermostat/ICV?? |
Quote: this is a dramatic power loss, though... like nearly stalling in the intersection outside my house as i pull into the roadway. i'll start out accelerating and literally fall against the seatbelt a bit under engine breaking.
car wasn't like this for the first couple thousand miles, as i remember.
my understanding is that a bad ICV or throttle control will manifest as a high idle or a really irregular fuel delivery ALL THE TIME.
and a bad thermostat seems to be a problem more when the engine is HOT, not when cold (i.e. they stick closed, not open).
i'm wondering if there's a fuel injection mapping thing going on BASED on the thermostat reading, though. i'm more of a motorcycle wrench than a car one, and i have heard about this on the BMW Kbikes before.
Thoughts? | I'd be suspicious of O2 sensor readings. Plug an OBD-II scanner in and watch them during warm-up. It might be taking too long to get to closed loop.
Thermostats do sometimes stick open. I've never had it happen (they've always stuck closed on me), but it can and does happen. Have you installed an oil temperature gauge or a real coolant temerature gauge? How long 'til it reaches operating temperature? Have you squeezed the upper radiator hose on cold start to feel if there's any coolant passing through it?
On the S54, I know the DME uses the oil temperature for VANOS. It uses the water temp as a backup if the oil temperature sensor fails. I'm not sure how the S52 works on this front.
| | Reply » S52 Bogging when cold; bad thermostat/ICV?? |
there was some kind of recall on rough cold running on this car on 12/09/99, but i don't know how to retrieve the bulletin. i guess the dealer can help, but i just bought the car and don't know or trust any dealers in the area, dunno how much they'll help. i'll ask of the forum, i guess!
i just know they'll tell me to bring it in, bone me, then tell me they fixed this and that and it should be better but it'll be the same! i don't have the OBD-II or specialized equipment like that, just a great set of metric cycle tools. don't even know how to get a hold of a good tech manual on the car (99 M Coupe). like i said, i just bought the car, so any help is appreciated any tech you have...
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S52 Bogging when cold; bad thermostat/ICV??