E30 325 sport mtech 1 missfire

[RossDavies]

Hi anybody got any experience with blue smoke and misfire on the M20 engines? Mines a 325 sport here's some pics. Got no pics of under the bonnet but everything is looking brand new. Was wondering maybe stem seals? Or anybody ever had blue smoke from just a spark misfire? Haven't looked into it yet but it smokes like hell when at worst and occasional backfire.

[Speedtouch]

How many miles has the engine done? If high mileage, it could be worn valve oil stem seals, but first check the crankcase breather hoses are all in good condition, and not blocked with sludge or split.

Misfire could be down to worn spark plugs, poor compression (carry out a compression test to ensure all six cylinders read around 170 psi), or possible failing crank sensor(s) - there is usually one tucked away in the gearbox bellhousing on Tech 1s.

[RossDavies]

Cheers for the info, whatever is causing the blue smoke is definitely causing the misfire because they came together, the engines on 125000miles and the oil is see through, has been really well looked after, would you get blue smoke from plugs/ sensor fault though?

[martauto]

I know these are different animals , but my 325 e46 had the same issues and at the end of the day it came down to the crank case ventilation valve which was no good (very common on the e46 but could still apply as some one said earlier)
Maybe worth looking at ?

Mart.

[HJ1981]

I know these are different animals , but my 325 e46 had the same issues and at the end of the day it came down to the crank case ventilation valve which was no good (very common on the e46 but could still apply as some one said earlier)
Maybe worth looking at ?

Mart.

Does the M20 have such a valve? i know we have the commonly known "bitch tube" under the intake manifold to the block, but i do not recall any kind of valve for the crankcase breather system, unless those earlier models were made differently?

[Brianmoooore]

How many of these threads are there??? This is #3 that I've seen, all identical!
I've just replied on one of the other versions, so to avoid confusion, I'm closing this one.
No crank case vent valve on a M20, BTW.