"TACK" noise under load?! What's this?

[dimi_108]

Hey people, it's question time from me again.
I'm getting this weird "pop" noise. Sort of like a small misfire/backfire under load some times.
It's happened twice so far. Once last night and once again tonight. All while giving it a boot.
The feeling is like boost cut for that split second - it goes "TACK". Then the car just sails away normally.

As you all know, performance-wise, the car is pretty standard.
I've recently installed a transmission cooler (yesterday) using the CVR4 and OZVR4 guide.
I'm using a manual boost controller as well (which i've dropped the boost already but still did the "pop" noise.
It only started yesterday after the transmission cooler was installed (could be a coincidence?).
I also changed my spark plugs today in hope to rectify this problem
Hmm and I had a squeaky belt last week which i sorted with some "Belt Grip" spray.

Does anybody have any idea what this is?? Like I said, It never used to happen until the transmission cooler got installed.

 

[bradc]

Any chance it could be the fuel level or a pipe just starting to come off?

 

[dimi_108]

Yeah i'm not too sure. I've asked the guys at CVR4 too (as you know) and a few people said it could be the leads or fuel pump.
Weird. It happened today on the cruise. It mainly happens in automatic mode not tiptronic. It will happen when severely under load. Like 4th gear and i'm stepping and the turbos are working hard.
I'll have to investigate a bit more and i'll report back my findings in case anybody has a similar issue in future.