SL 2002 engine gurgling noise

I have a Saturn SL 2002 (bought from the last batch, they run special
in June 2002). When engine is warm/hot, it is making a gurgling noise
(like a roaring sound). It often happend when a gas pedal is released
(close to idle speed). So, 3 months ago brought it in for diagnostics.

Service checked for codes found 1599 indicating near stall, no other codes.
Checked for calibration. Calibration current in ECM/BCM.
Checked for bulletins - none found.
Run misfire graph test - no misfires on any cilinders.
Checked plugs - all gapped at .40", Plug wares and coils - tested OK.

Tech stated the car may have bad gas running through it. At that time
I was using mostly local Mobile, so switched to Shell. Now, 3 months later,
I have the same problem. What it can be and what should I do?

I appreciate any replies.
Thank you.

Jerry

 

The problem description is pretty vague - is the engine running rough when
this is happening?

The 2002 S-cars are equipped with an electric air injection pump system
which will come on under certain conditions, could that be what you're
hearing?

 

It doesn't seem like the engine is running rough when this is happening.
Where that air injection pump system is located? It looks like the sound
is originated around valve cover/top left (standing in a front of the car
facing motor compartment) part of the engine.
And yes, the Saturn's service department did confirm the problem...

Thank you.

Jerry

 

The AIR pump itself seems to be in the front left (i.e. passenger's side) of
the engine compartment. There are also some other components attached to it
(check valve,solenoid, combination valve). I have not seen any of these cars
firsthand, but it's probably quite audible when it kicks in. Don't know if
"gurgling" is the kind of sound it would make though..

 

Thank you for reply. I don't think it sounds like the AIR pump.
I think that gurgling sound started when I began using aftermarket oil filters
(Purolator, Fram) instead of more expesive OEM filters (I change oil myself).
Could it be just a coincidence?

Jerry