I'm at a complete loss with this issue, full details of it are below, but I'm wondering if this could be caused by the eManage Blue?
I realise I may get a lot of hate for this setup, but in it's defense it's worked perfectly for years. The ECU/setup was installed by a reputable tuner in the UK, I've never had any reason to investigate the tune etc. The car does multiple trackdays per year and enver misses a beat.
the car is a 1.8, with an M45 coldside kit. eManage for engine management, (therefore the MAF is still in use)
I've checked for vac leaks and in the process have replaced the entire inlet pipework from the MAF to the TB for new. The bypass valve had also failed, (that was obviously now a vac leak there), so have also replaced that.
I've also swapped to a new TB, TPS and IAC. I've put in a new O2 sensor. I've removed and resealed the blower and all the adapter plates. I've tried a replacement MAF.
I've reset the base idle, I've setup the TPS position correctly, (0.3mm off the stop and there is no continuity from the idle switch, I've confirmed tat the timing is set to 10deg, (pulley hasn't slipped either)
Fixing the few vac leaks has obviously made the issue better, but changing all of those parts hasn't made one iota of a difference as in it still does it, It's still not fixed.
Any ideas at all?
link to a video of what is happening is below. You can see/hear the idle is nice and steady, then I blip the throttle and it returns to idle nicely. After a couple of seconds the idle then drops and missfires slightly, this happens for 30 seconds after which the idle returns to normal: