After replacing my radiator I started with a distilled water/white vinegar mix, then three rounds of water flushes. On the water flushes I used the factory-preferred method and had some pretty interesting results.

Before I explain what happened, let me tell you what did NOT happen:

• The engine did not overheat.  The temp gauge didn't budge above normal at all after reaching operating temperature. I attribute this to massaging the radiator hoses a whole bunch before capping the system each time.

• The check engine lamp never came on. As in, not once. Not even a flicker.

• I did not change throttle position at all when the phenomena began, until noted in the video.

• It was repeatable enough to happen on three consecutive "burps."

So, what did happen? About 6 or 7 minutes into my 10 minute burp procedure, I would lose control of the throttle. Mind you, this is a drive-by-cable throttle, and I hadn't changed the throttle position at all.

When this happened the rpms would drop down to about 1,250, then up to 1,750 rpm and repeat until I either floored the throttle, or backed out and let the engine idle.
 

What the hell is going on?

 

hmmm

 

did the rad fans cycle on-off?

Edited March 25, 201511 yr by 1 Lucky Texan

Yes, although it was hard to hear over the exhaust.

I had one fellow on NASIOC suggest that it could be an IAC gasket issue, but I don’t have any sort of idle problems.  The engine has only misbehaved during the coolant burp procedure.
 

Was the battery disconnected while doing the work?

 

Also What year? and does it have Electronic throttle?

Edited March 31, 201511 yr by Fairtax4me

2002 WRX, drive-by-cable.

 

Battery was connected, car was running when it happened.