While you are under there -

https://www.ukcorsa-d.com/posts/2266978/

 

Thanks no error codes yet. I’m leaning more to an injector gone (it’s got 230k km on it) but read hoping it might just be the maf

 

Water damage is the common killer here have you checked the ECU?

 

The hose in your picture is the part of the crankcase ventilation system and any leaks in it will cause air to fuel mixes to be wrong as the ecu will be seeing incorrect air data.
Is it definitely a Z13DTJ?
I've only ever seen the routing of your hose on the A13DTC engines. In the Z13DTJ's I've played with the crankcase hose runs behind the intake then round the side of the vacuum and fuel pump then connects behind the u-bend that goes to the turbo (see pic).
Has it been serviced recently?
Egr issues can cause cold start running problems.
Can you post live data on a cold start at idle?

2010 Z13DTJ:

 

Thanks the log book says z13dtj but I guess it coulda have had engine swap. I’ll check block tonight and run cold stats.

 

So diagnostics confirm it’s a z13dtj Antwerp B for that’s worth. I taped the hose that was caked in oil and soot but it didn’t make any difference (white in pic attached). And I’ve run a new capture starting from cold. What I did notice was at idle / 800rpm at start the maf is at around 4g/sec and feels rough after 3 or minutes the maf is at 8g/sec and didn’t feel so bad. 2 screenshots attached. Not sure why the maf would be different at idle??

 

Cold start (+24 hours without moving outside +10C)

 

Should you be able to see the air filter like this?? I assume if badly fitted then too much air getting in etc so rough run?

 

Maf figures vary due to egr operation, more duty cycle on the egr means less air drawn in past the maf. You could unplug the egr and see how she runs on a cold start. If you read maf figures with the egr unplugged it should be 9.0 g/s +.
The filter fitting won't make any difference as it's before the maf, it's only air/boost leaks after the maf that will mess things up. What condition is the air filter in? Has the car been serviced recently?
If there is soot on the crank breather hose that would mean exhaust gases are escaping from somewhere and due to it's location I'd suspect blow by from the injectors... is there any signs of injectors not sealing properly?

 

Hi, we just got the car but I’m told it was serviced recently - although the fuel filter looks old and as per the photo above you can see the edge of the air filter in the box (which seems wrongly secured to me?)

if it was an injector then I’d expect it to be rough throughout? But once it’s been driving for a while it’s fine. There’s no loss of power and no smoke etc. there is a huge blast of soot out of the exhaust if rev hard (4-5k rev) as put hand near the exhaust and it will be black after the rev. But no smoke!

if it was blow by then I’d expect that white tape I’ve put round the breather pipe to be covered by now (done 100km in it last night).

I don’t want to waste too much cash on it as she only needs it for 6 months to learn in. I guess I’ll get the garage to change that breather pipe and give it a full service, see where we are then? I threw a double shot of redex in last night as well just for a laugh.