Ok when I bought the car it was running odd and here is the story First I wanna kill the mechanic who worked on this car. When he put the air filter on he pinched the wire to the aux fan switch (temp sensor green top three prong) (not guage sensor). The sonsor started to go out so when I would take off when the car was hot it would die. Well changed sensor and it runs good now BUT when I start the car the idle does not rise when cold. It idles at around 800rpms and when put in drive it drops to 650 and the idles ruff. AND the aux fan wont turn on. So can you please tell me what sensor or fuze or relay or what controls the idle.

 

No one know nothing? I did some research and they said ovp realy behind battery. Is that right?

 

What year ,what model,what engine?Any codes?
Why did you buy a car with a problem engine?You want anwsers ,we have questions.
ohlord

Cold Start Valve
Engine Temperature Sensor

ohlord
www.autohausaz.com

 

The car was running good when I bought it. I suspect the wire melted after I had it because he had a tune up the day before I bought it and got it for an awesome price. Its a 300 86 mercedes with the 3.0 inline 6

 

Forgot no codes, new o2 sensor, and new temp sensor (green top 3 prong) Also Aux fan fuze was blown replaced it work for a minute then stopped working fuze still good (fuze in fuze box)

 

Check the fuse with a multimeter set to ohms zero = blown fuse.
something is making the fuse burn out so that will need to be traced.
Instead of having to throw parts at it it might be wiser to get it on a scope at an indie shop and check values of the sensors.
ohlord

 

Im posotive that when the wire grounded out on the sensor it blew the fuze. Well didnt blow the fuze. it looked totally worn but I will check all the fuzes with ohm meter. So what cintrols the idle anyways?

 

coolant temp sensor,idle control valve,cold start valve.Most often the cold start valve.
You can also check with more people that may have ran into the exact problem on mbworld.org 300e forum.
ohlord

 

idle valve new, cold start valve new, and temp sensor new. Still same problem. SO what should happen when you unplug your temp sensor (green top 3 prong) Where does the electricity go from there. I checked the red top relay with the single red fuze. FUze good opened the relay and all solder is good. Relay appears good. NEXT STEP????

 

You have ran all the checks I can think of and replaced the most critical sensors.I'm stumped
And that takes a lot
I will ask around and see if a retired mb tech I know has any additional ideas short of getting it on the machine.
ohlord