[Wadger]

Hi All,

2007
AT
69k
Charge Pipe and BOV
Stage 1 map (not confirmed)
DCI
Injectors replaced 3 years ago
HPFP replaced 6 years ago
Has done less than 20k since the HPFP and Injectors were replaced.
Oil changed under 2k miles ago
Walnut blast under 2k miles ago
Boost Solenoids replaced under 500 miles ago.
Not sure when plugs and coils were last changed.
Alpina B3 Flash
Gearbox serviced under 1k

I am experiencing a slight issue with a RPM drop after light throttle at idle.

I know the following is not at idle, however I first suspected something wrong when I pulled away in a Tesco car park, I was in second up to about 2.5k and let off the throttle, the RPM dropped quick but instantly picked back up.
It all happened so fast I weren't sure if it was in my head or not.
However I could not replicate this again so im still not sure haha.

Now upon engine idling at about 550-600(as always), I will give it a little/fast blip up to 1k and the revs will fall back down fast, sometimes going down as far as maybe 250, before instantly picking back up to normal. It does the drop to varying degrees every time I do this, sometimes with no issue at all.

After doing this 5 or 6 times parked up, the idle stayed at about 700-750 solid, even after blipping again etc. I couldn't get it back down unless I restarted the engine.

I have always had the slight juddering at idle, in the sense I will feel the car shake very slightly every now and then, however the RPM never moves. I thought this may be normal but not so sure after doing some reading.

If I rev up to around 2k, I don't see any issues.
The car still pulls very well under load with no apparent issues.

Not sure if this is related, but I have noticed the exhaust popping a bit more on some occasions when letting off in second, Im not sure what variables would affect this or if it is again in my head because im listening to every little thing trying to find something.

This might even be normal where Im tapping the throttle so slightly/fast and trying to find something wrong after my moment at Tesco

I have read lots of posts on some things similar, however they all seem to include additional issues with the revs dropping or hanging.

My initial thoughts are the following.
Plugs - Planning to change now regardless.
Coils
BOV and/or Vacuum lines? My vacuum line for BOV is probably a bit long but im nowhere near boost at 1k?
Oxygen sensors
Throttle Body dirty

I am hoping this is something easy that maybe im taking for granted.

I have INPA etc from when I done the Alpina Flash, so is there anything I can check using these tools?
It has not thrown a code or anything, but there is so much about this software I don't know, so this might be a little opportunity to learn some more

Thanks for taking the time to read!

Ryan