haunting idle

[Sergioe46m3]

Guys i have a horrible hauting idle when the car is cold it idles normaly but as soon as the car gets to normal runing temp it idles horribly car feels normal onder load its just at stand stills that the idle is bad car is a 87 325e btw thanks

[e30Villain]

Change your temp sensor. Cheapest part and is popular culprit.

[TylerEstes]

Do the revs fluctuate? My 325e did that, but then I saw that a vacuum hose had become disconnected so I plugged it back in and it completely fixed it. Check your hoses if you haven't done so yet.

It's also worth noting that your mass airflow sensor (?) housing (the thing that your air intake goes into) hose ripped?

This is mine before I plugged that hose back in. I ripped the bigger hose that it plugged into and the same problem came back up until I wrapped tape around it.

[Sergioe46m3]

Yea unfortunatly i checked all hoses for vacum leaks and nothing :/

[Sergioe46m3]

and why would the temp sensor affect idle?

[Timmyboy]

when the car reaches operating temp the thermostat opens and then that sensor provides information to the DME for it to run smoothly. make sure you get the right sensor!

[e30Villain]

Its the coolant temperature sensor not the outside temperature sensor.

I just changed mine out and it did wonders for my idle.