E30 Zone

I started my m50 today It fired up first time but is Idling at 1500 rpm and after about a minute It starts reving up and down and the idle creeps up to 2500 rpm
The o2 sensor is new and the airmass meter
The engine was run without the o2 sensor has this put the ecu into fault mode
and if it has how can i reset it .

with the o2 sensor reconnected it should be fine..

mine has a similar idle issue atm, altho not a high idle

check for air leaks.. Is the inlet elbow ok? try spraying a bit of wd-40 on the pipes etc and listen for any changes..

also have you checked the position of the throttle plate is closed when on idle?

I put all new hoses on when i put the engine in and the throttle plate is closing all right
I must check the o2 sensor plug isnt corroded

have you connected all the breathers back up properly?

I will check them out but I think so

I had the same high idle issue when I first started it.. I found I had left the breather on the back of the manifold off..

Someone did....

I wish it was just a steady high idle but it revs up and down and the rev increase after a while

you should check the hose coming from the idle valve to the intake manifold,
did you remove the loom from the engine? i had the same problem on a m50 motor and the problem was that i connected the camshaft position sensor with the idle control connector and vice versa. the motor will start and run but the idle was high and oscilated

Yea had the loom out alright but marked everthing up
I will check it any way thanks for the advise !

Just to let you know I got the problem sorted it was the ICV that was worn out it would open but very slow closing .
I fitted the one out of the old m20 but will have to get a new one as it isnt great and sometimes the idle gets unstable but not to often