316i M40 rough idle and jerky at 30 km/h

[Skajohyros]

Greetings.

I've searched some threads but still at a loss.
Idle is rough, searching, surging. It's also jerky doing 25-30km/h in second gear(about 1500-2000rpm), also noticeable in third at same rpm. Exhaust fumes smell bad.

What I've done so far:
Tried another AFM(forgot to reset ECU, does it matter?), throttle body with TPS.
Cleaned ICV and drove it with sensor disconnected (problem was still there) so maybe I can rule out the ICV as being the problem?
Replaced intake elbow, rocker vent hose and the ICV hose.
Have not done vacuum test or fuel pressure test.
Any advice would be much appreciated.
Frustrated.

Video of problem. Hope you can hear it.

[Brianmoooore]

Can't really hear the problem, but your description is of a car with a weak mixture at idle.
You're stating speed in km/h, which suggests this is not a UK car, so does it have a cat. and lambda sensor?
Air leaks after the AFM , injectors long overdue for a service or fuel pressure problems, in that order.

[Skajohyros]

Thanks for replying. I'm in Greece, no lambda sensor. Not sure if it's a cat or front silencer under the car.
Fuel pressure up to the rails has been tested ok. Could it be a faulty fuel pressure regulator?
Don't know what condition the injectors are in.
I'm planning to check the blue sensor.
Would not a vacuum leak affect all rpm range?
Cheers for the input.

[Brianmoooore]

If there's no lambda sensor, the front box will be a silencer/ x pipe.
If the fuel pressure has been checked and found to be OK, then the pressure regulator is unlikely to be at fault.
Blue sensor failure usually makes the mixture rich. Would be an unusual failure to make it weak when the car is at running temperature. I could be wrong about the weak mixture, of course, since I can't hear the fault, and if the problem is a rich mixture, then the blue sensor or its wiring is a likely candidate. An examination of the spark plug tips should provide an indication of rich or weak.
Vacuum leak would affect things throughout the whole rev. range, but mixture is already designed to be as weak as possible at idle, and, because inlet plenum pressure is lowest at idle, a given leak will admit more air under these conditions than when the throttle is open. Also, a given leak will be a greater proportion of the total airflow into the engine under light or no load.

[Skajohyros]

I can't tell from the plugs if it's running rich or lean.

[Skajohyros]

Also took blue temp sensor reading at ECU.
Cold-1700
Hot-190
Isn't this very low?
Will try taking readings at sensor.

[Brianmoooore]

Also took blue temp sensor reading at ECU.
Cold-1700
Hot-190
Isn't this very low?
Will try taking readings at sensor.

Cold reading would be on the low side for the UK, but it depends on the ambient temperature.
Your plug tips show an engine that is running a little lean, IMHO.

[Skajohyros]

Ambient temperature is about 28°. So is 1700 normal enough? Is the hot reading low?

[Brianmoooore]

http://www.bosch-motorsport.de/content/ ... TC_M12.pdf

[Skajohyros]

Cheers mate. Seems normal enough.