Idles too low (accelerates with hesitation) after cold start
 

Hi guys. I own the european 1994 318ti with M42B18 and manual transmission.

Few weeks ago I have noticed that something is wrong with the car. There are two sympthoms and they both appeared in about the same time. So I don't really know it is the one fault or more of them.
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To begin with, the car doesn't run properly after the cold start (when the engine is cold). As you can see in the video, it cranks a bit too long and after it the engine runs poor, idle is too low and a bit rough. During this time I can rev the engine only if I push the pedal slowly, because if I push it quickly, the engine tends to die, struggles to work. As I said you can see and hear it in the video. This happens for a minute or less and later there are no problems with starting (however once this happend with warm engine).



In addition to this, sometimes while driving the car (doesn't matter cold or hot) I can feel that it starts to accelerate itself. Idle is too high - ~1500rpm. This happens for a short period of time. After few minutes or less the idle drops.
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Dear people, could you share your ideas what is possibly wrong with my BMW?
I had the car scanned for a fault codes - it showed the temperature sensor. The sensor's plug is OK, it gets right voltage and so on. Also I've changed two of them - no difference. Moreover, I have cleaned the idle control valve, changed it with another - also no difference.
I don't really know what else could be wrong. Please give some help. :frown:

a 93 ti? how old is your fuel filter? sounds like a fuel pressure issue. does your pump prime when your turn the ignition on before starting?

Oh sorry, typing mistake about the manufacturing years. It is 94.
Yep, I can hear fuel pump buzzing for a few seconds when I turn the ignition on. However, I don't have any idea how old is fuel filter - never replaced it.

Dirty air filter, worn out upstream O2, vacuum leaks before TB. These are my only guesses that would throw a CEL.

Also clean the ICV just to be safe and eliminate that as a issue.

Well... ICV clean would be easy fix, but trust me my ICV is really clean. I have even tried to put another one, but it didn't solve the problem.
Dirty air filter? Well visually it doesn't look dirty at all, was changed 4000miles ago. There are no vacuum leaks too (it was the first thing I have checked).
O2 sensor? May be possible, but as long as I know it doesn't work until heats up. So I guess it can't affect the fuel mixture right after the start of the engine. :frown:
Correct me, please, if I am wrong.

Got me stumped I didn't know you had already did all the work listed above

Everything is ok. :smile: Any ideas are welcome! I just always try to check everything if anything goes wrong but this time... I don't have any ideas left.

CPS
 

Was it your Crankshaft Position Sensor?

pcv valve?? Im having the same problem and all of the main supporters on this site told me it is most likely the pcv

PCV
 

I don't think we have a PCV (Positive Crankcase Ventilation) valve on our cars. Did you mean ICV (Idle Control Valve?

I ordered a CPS (Crankshaft Position Sensor) today, since my car starts rough first thing in the morning whether it is cold or hot outside, and at times takes a couple of cranks, or one long one to get it to start. Same symptoms that a 328is of mine had and the crank sensor was the problem.

The to has a crankcase vent valve or pcv valve whichever you prefer cause I know I have seen it both ways and it is located right next to the dipstick its a little round plastic thing with two Allen screws underneath holding it in place and a hose connected to it which is called the crankcase vent hose leads behind the intake manifold over to the block, if the valve is bad it causes bad idle or jumping idles poor start ups and loss of power same with the hose being cracked

ICV
 

That is the ICV (Idle Control Valve) you are talking about. Yes, if they get dirty or a hose cracks and lets vacuum pass through it, you will have the issues you are talking about.

Number 11 on the diagram is the pcv and the other pic is the icv, they are separate parts that the ti has both of, i have a thread similar to this one you can search it if you would like

PCV
 

I stand corrected. I've even removed this and cleaned it before, but didn't realize it was a PCV valve; now I know.

hey its no big deal these cars are tricky, but i did not know this either until the other supporters helped me out, im replacing this soon i ordered one and it should be here today or tomorrow and im installing it right away so i will let you know if it helps any
-zach