Hmmm.... generally pciii's shouldn't need remapping after they are dyno'd.

Popping in the exhaust on decel is normally due to an air leak and a rich mixture, which I have on a regular basis and is the way that the dyno tech set it up. It has gotten worse, it seems, over the past 6 months.

When this happens, it pops out of both the throttle body and exhaust as it would on a lean condition. That's why I was hoping it was a fuel pressure issue... easy to find, not too bad to fix.

It could be something fouling the fuel filter on an intermittent basis, also.

As to opening the gas tank to let off pressure, this shouldn't be necessary unless there is a leak in the lines associated with the fuel pump or the pump itself. No other way that pressure could change to the point that it would make a difference... (i.e. heat won't do it by itself).

I just hate to figure this out by getting stranded but it sure is a quirky thing... totally unpredictable so far.

Thanks for everyone's suggestions.

C#

 

Checking the PCIII with a laptop was a simple thing just to look at the MAP and to rule that out and it would cost no $$. (You are correct, it should not change)
As I stated it does sound like a LEAN condition and spraying WD40 around the intake area would check for intake leaks as in "sucking in air".
Opening the gas cap has nothing to do with the fuel pump, only to allow AIR into the tank in case the vent line that is supposed to do it is restricted or plugged. If you have a vacuum in the tank, the fuel pressure will drop making a lean condition. Opening the cap slightly (about 1 turn) will balance the air in the tank if the line is restricted.
These basic tests don't cost any $$$ to try.

None of this may apply to what is wrong with your situation just basic tests.
I chased that loose spark plug wire around for a while, thinking it was something really expensive.

Again, I am just trying some suggestion to help.

Just as a note, my PCIII on my 07 NT is set richer at OFF throttle (idle) and my exhaust popping is gone.