I have a 95 318TI. I recently replaced the O2 sensor, ICV hoses, injector hoses, and cleaned the ICV, cleaned the MAF. On cold starts my car will idle at about 1500 RPM's until it warms up, then it will slowly drop down to 700ish. Once it's warm when I come to a stop it will idle at 1500 RPM's and again slowly drop down to 700 or so RPM's. I have tried checking for vacuum leaks by spraying some starter fluid on the vacuum lines and did not notice an increase in RPM's.
In DME's there is a rolling idle and stop idle programmed. The rolling idle is around 1,200 and when you come to a complete stop the idle should drop around 700-800. I don't have the exact RPM's for the rolling and stock idle since mine are altered but it is suppose to do that unless it has started to do it with a large swing in idle or different since you have owned the car.
I just purchased the car recently, so I don't really know what was normal for the car. I just think it is kind of odd that it idles so high on a cold start, but not on a warm start. Once it is idling normal and I rev it up it will come down to 1500 and slowly go back down to 700. I did notice that the temp gauge seemed to be unsteady this morning when I started it to check. The gauge would go up to the middle line, then back down to about 1/4. It did this a couple of times. Could it be the temp sensors?
I just unplugged my ICV and my car idled perfectly. I revved it up and it came down normally. Does this mean I should try cleaning it again...or is it time to replace it?
Yes, as you stated your temp went to 1/2 then back down to 1/4. This tells me your t-stat is sticking open and needs to be replaced before it sticks shut. Also inconsistant water temps in the block could throw off the idle control or lambda adaption settings.
On the fast idle is this a stick shift? If so I would think that is normal idle. The ICV disconnect would just confirm that your TB setting is correct. My car runs about the same and unless another board member chimes in and states this is a idle issue I would consider it normal operation of the I-4 BMW motor.
Yes, it is a stick shift. I tried cleaning the ICV again and the car wouldn't start when I put it back in, so I ordered a new one and it still runs the same.
I have a thermostat on the way so we will see if that helps. Could there possibly be air in the cooling system causing inconsistent readings? Or maybe the O2 sensor I put in isn't the right one?
Maybe this video will help to show what's going on. This is after a 41 mile drive home. Coming to a stop you can see the rolling idle...then when the speedometer drops down to 0 you can see how long the RPM's hang. Also, I used a quarter tank driving 82 miles (about 80 of them are freeway miles), this just doesn't seem right.
Does this seem normal?
I'll try to get some footage of a cold start tomorrow morning...