[ManiacGT]

So I’ve not had chance to try the altered map as yet but I have been studying the engine a little more and I wonder if I can test this theory with you all;

I recall when I first got the car back from the injector/water pump repair hearing a new relatively quiet warbling type noise entering the cabin from the engine area. I had no idea what this was and it’s either subsided or I’ve gotten used to it now as I don’t notice it any longer.

However having studied the forced induction system and some of the reasoning and side effects parts of it are designed to address I’ve started to focus on the blow off system.

Reading up on this there are two reasons for this system, one is to reduce an unwanted pressure noise when the throttle flap closes due to the oscillating back pressure and the other to reduce axial wear on the turbos / avoid a stall like situation on the blades.

Now this made me think, if the blow off system wasn’t functioning properly, this may explain the warble/flutter I heard and possibly also the power drop just before and just after the gear change as first the turbos slow due to back pressure from throttle closure and then take time to spool back up once the throttle opens post shift...

Does this make sense?

So I’m going to perform some further diagnostics. I’m going to perform the diverter to BOV change where you unplug and cap off the diverter to turbo intakes. That will allow me to hear if they are working or not. One at a time.

Also I’m going to disconnect the vacuum feed to the BOVs, plug the intake (carefully, I've read the horror stories of snapping this) and drive around the block carefully to see what the impact is. It’s either going to be much worse or no different if I’m on the money with it.

If this does indicate something then there is either a leak in the intake manifold or something wrong with the vacuum pipes or BOVs.