Boost issue.....again

After weeks of doing full on DIY I took the GTA out for a run yesterday only to find it has boost running issues again.
Drove it steadily for a few miles to warm it up. I then gave it some beans along the A31 only to find it hesitating and it threw what appeared to be a small cloud of black soot out the back end.
The boost needle flies to the right, so it's demanding power, so I'm thinking a poor connector on the ECU / ignition leads / coil pack / earthing strap ?

Boost actuator is new, boost actuator hose is on tight, spark plugs have been changed earlier this year, both fuel filters are quite new, fuel pump connections (front and rear) have been cleaned very recently.

Coil pack has been changed once since owning the car.

Also, not sure if this is relevant but sometimes (say a couple of times a year), the engine management warning lamp flickers on / off when driving.

It starts fine and drives ok apart from when you put your foot down.

Any thoughts?

Have you checked the dizzy and rotor arm?

Rotor and dizzy were replaced in April.

Since posting, I disconnected the battery and then took off the two connectors from the Coil Pack. Sprayed them with switch cleaner and reconnected. Plus (and I don't know why) I decided to undo the two connectors behind the off side rear wheel. I think this was because someone here mentioned about bad starting and that these connectors are exposed to the elements.
I undid the 13 & 10 mm nuts, cleaned off the crap, emery papered both, reassembled and spread them with oxide grease.

Took her for a run and it drove fine on full boost.
Perhaps a coincidence ?
So are these the main connectors from the battery to the engine and beyond? Would a dicky connection / high resistance cause some running issues ?

Perhaps a coincidence ?
So are these the main connectors from the battery to the engine and beyond? Would a dicky connection / high resistance cause some running issues ?

Paul ..... I don't think anyone can say whether it is coincidental or not, ...... But what I can say is that through those main connections that take the battery voltage to the starter, 12 volts are taken off for The Fuel Pump Relay, The Injection Locking Relay, and 12 volts Before Ignition for the ECU. As I said in my previous post about this connection, Any form of resistance in this connectors can have a detrimental effect in the performance of these engines, ......... whether it did in this case, you can only hope, but what you did was well worth doing, .... be pleased with yourself.
BUT .......... I would not use emery paper to clean connections as it is all to easy to rub through the tinned plating on them, I favour a Brass Bristled Brush like a spark plug brush for doing this type of thing.
Draper sell a pack of three brushes, quite cheap, which have a Brass Bristled, a Nylon Bristled ans a Stainless Steel Bristled brush in a blister pack ..... well worth having in your tool box.

John

Thanks John, I'll 'bank' the comment ref emery paper etc..

I notice there are three other connectors close to the one I undid - one I know is the connector for the speedo sensor. Do you know what the other two are connecting ? Suffice to say I didn't touch them for the time being, but I was in one of those 'contact cleaner' moods !

Lower engine loom bits and bobs ...Alt,oil level sensor,pressure ,reverse lights etc ...one to note is that the alt earth is also the rear fuel pump earth