Limp mode and misfire sensation- no fault codes

[chowmouse]

Hi there.

 

I was hoping someone here can assist with a strange issue I am having with my 2006 Subaru Legacy 2.0 naturally aspirated manual (EJ20).

 

The car will hesitate and splutter throughout the rpm range on acceleration any more than about 30%. At between 2000 and 3000 the issue is worst. The car feels as if the fuel is being cut as I am driving. Ironically giving it full throttle makes it worse, I need to drive around feathering the throttle.

 

Now, here where it gets interesting: I have no codes, ever. I can use my scan tool to "Clear all emissions data". Once I do this the car will run smooth and well for about 15 minutes before the problem returns. It's as if the car learns to misbehave after being reset.

I have tried replacing plugs and coils, carrying out an upper engine clean and cleaning out the MAF.

Note: I disassembled the EGR valve (right side) to clean it. The carbon buildup was not high, but the seal inside the EGR was bad. I have not replaced it at this time but I did run the car with it unplugged (which did throw an engine light) but the vehicle still drove the same.

 

Can anyone shed any light on the issue? Any assistance or pointers would be great.

[derache123]

I don't have much to offer but it seems like the OP from this thead https://legacygt.com/forums/showthread.php/low-torque-between-2000-3000rpm-hill-285092.html was experiencing something similar, perhaps this could shed some light?