the5rivers

Hey guys, been a lurker for awhile, and got some valuable info from this forum! Thanks! Just wanted to see if anyone could offer any thoughts/opinions/experience on my situation.

Here's my story:

I have a 05 545i, and a couple of months ago I started noticing a rough idle during start up. It felt like the engine was about to stall and die. Then a couple of weeks after I noticed the rough idle, sure enough the engine did die twice while I was driving around town. The engine just died while I was waiting at a red light. Put the car in park and restarted and it was good to go. A couple of weeks after those incidences, still had the rough idle during startup, and still felt the engine was about to die when in park or sitting at a red light, although it didn't die other than the first two times I previously mentioned. The car would have a rough idle at low rpm's (around 500), and it would shudder a little, like it was about to stall and die. Finally, the check engine light came on with the "increased emissions" error code. So I made an appointment to take it to the dealer.

I did some research on this forum, particularly this thread: https://5series.net/forums/topic/916...eo-sound-bite/.
Some of the issues I have were the same, but I didnt have any engine ticking/knocking as shown in the video/soundbite. I also had a subtle rpm jump, only from 500-700 during startup, and it happened occasionally.

I also found two TSB's regarding rough idle at startup (11 02 05, 11 07 06), hoping maybe those were the problems with the engine.

Took it to the dealer today, and explained my situation, and gave them the TSB's as well. Dealer just called and said they could not find any of the error codes relating to the TSB's I gave them, but they found one error code (2ef4) relating to TSB 12 15 05, which was a thermostat fault. They said that they have to replace the thermostat first, and see if the check engine light comes back on. If it does, the next step was replacing the engine wiring harness, which they said costs $2400-2600.

When I pressed my SA on how the rough idle/engine dying was related to the thermostat failure, he could not give me a very good explanation, and kept referring to it as " this is the error code that came up and this is what would be the first step in fixing the problems you are having." Definitely was not happy with his explanation, but I knew that before I asked him, and just wanted to hear what he had to say. So I am getting the thermostat replaced right now.

I am trying to find some correlations between the thermostat failure and the rough idle/engine dying, and I am hoping that replacing it will solve my problems, because replacing the engine wiring harness is pretty expensive, and I don't know if doing that would fix the problems I am having.

I just wanted some thoughts/opinions on my situation. Any info would be appreciated! Thanks so much, and sorry for the long first post.

2exclusive

maybe the car was overheating which caused it to shutdown... i heard in another thread that the car will shutdown to prevent overheating... maybe this might be the cause... rough idle jumping from 500 t0 700 happens to me as well but i had read that this is not a major issue but a known one when the car is cold.

the5rivers

Alright thanks for the info I really appreciate it. Going to go pick up the car in about an hour, dealer said he drove it and error light is gone, and engine idle seems smoother, etc. Heres hoping!

I didnt know that the engine would just shut off automatically, that is good to know though. And it makes sense that there was no high temp warning because the thermostat was faulty. Thanks for the info about the rpm swing too!

Jon M5

If the problem isn't solved, let us know. I had this EXACT same issue with my M5 last year, but I can't remember what BMW did to fix it. I can find out on Monday though and let you know if your car isn't fixed still.

the5rivers

Hey guys, so got the car on Friday, and have put about 100 miles on it since then. All seems OK! As soon as I picked up the car, I could already notice a difference in the idle as well as the revs. Overall driving is much smoother now, and idling in park or at a red light doesnt cause the rpm swing, nor does it seem like the car is about to stall and die.

Hopefully the engine light doesn't come back on, because if it does my SA said that it means the engine wiring harness would be the fault, and would have to be replaced.

JonM5, if you wouldn't mind, could you tell me what you had done to your car to resolve the problem? I figure the more info I have about this issue the better. Thanks again!!

Mo545i

Hi,

I am having the the same issues. My 2005 545i, 65k mikes, has a fluctuating idle occasionally that jumps from 500 to 900 at idle. This happens at stop lights, stop signs, or even at starts. It is not regular but happens at least once about every 2 days. As well my car experiences a rough idle at start as well. Seems to happen more often when the engine is warm. The idle jumps between 400-1200 rmps. It almost feels as though the car will stall and has stalled twice. I brought the car into a local independent shop to have them check it out. They addressed both SIBs for the rough idle. They adjusted the lifters, increased idle and verified I have the latest software. I use Chevron gas regulary and the spark plugs say they do not need to be replaced for another 35k. The only recent work done was replacing the water pump and thermostat. Has anybody experienced the same issues and had them resolved? Or think they know what is going on. I appreciate any help.

jm545i

They go straight from thermostat to engine wiring harness? Glad it worked out but you need a new dealer/SA. What a joke. There are probably about 50 things that could set a check engine light that require merely the replacement of a sensor.

Mo545i

I forgot to mention I have no service codecs or check engine lights.

healthservices

And you tried replacing the 'pressure regulating valves' already?

Mo545i

Not yet, I will discuss with the shop in Tuesday. Thanks for the input.