Hello everyone. I've got an intermittent problem with my Impreza. My 97 OBS 2.2 with a hand full of mods. At 265,000 the engine burns zero oil, no leaks, great compression. The problem is that most of the time during acceleration, whether at WOT or just normal, it feels as though something is holding the car back. The reason I know this is cause after the car sits for a few days without being driven and I take it for a drive I notice that the acceleration is smoother than usual, and the car just goes very easily. WOT at this time is awesome! Its quick and has a lot more torque, significantly more MPG, and it just purrs. But after driving, say for 10 miles or so it just kinda goes back to its old self: not as smooth acceleration, MPG goes down, less torque, and it feels like the E-brake is slightly on. Just changed the diff and manual fluids. IDK anyone got any ideas?

Probably running a little too lean.

How old are plugs wires and filters?

PCV valve?

kinda wonder if vacuum gauge comaprisons before/after might point to an exhaust blockage, vacuum leak (intake gasket?) or some other issue?

 

might be worth measuring the hubs and rotors with an infrared thermometer. maybe a caliper is dragging?

 

any 'jerkiness' to the 'holding back' feeling?

Edited July 9, 201411 yr by 1 Lucky Texan

Agree with the old-school vacuum gauge, systems are much more complex nowadays but it's still just a big air pump!

Plugs and wires are new. I dont think there is an exhaust blockage. Just upgraded to EL headers and a magnaflow front cat. New gaskets all the way back. Intake gasket leak is a possibility. As for it running too lean....hmmm...when I pulled off the stock exhaust manifold I did notice that the exhaust valves did look pretty white. I was kinda thinking along the line of a possible fuel delivery problem? I have not changed the fuel filter. I will do that. Perhaps the fuel pump is faulty? Like there is proper fuel pressure for the first 20 min then it drops? Is this even a possibility? Can a fuel pump have that symptom? Im replacing the front pads and rotors soon. The rear are drum so I should check them out. It is a definite possibility that one could be dragging a bit.