I just got a 99 impreza sport wagon 2.2 5 speed 175k. The previous owner said it had a lack of power. After trailering it home, I drove it around for about 30 minuy es with no problem. I decided to do timing and reseal. Got done drove great for about an hour then started having problems they were talking about.

 

It definitely has a lack of power at times. If I try, I can find the sweet spot with the gas pedal and it does great. A little to much or not enough and it loses power. If I floor it, it will kick in and run fine. It does this in all gears.

 

I put a new fuel filter on it, because it was easy, but no change.

 

Any help would be great.

 

Thanks

Dp

Are there any CEL Codes?

 

The mass airflow sensor could be going out.

scan for codes as said

 

possible exhaust blockage or knock sensor - but any codes will be important

No codes no cel.

 

I did scan it and check live data and noticed my tps is flat lined at 0 while idling. I loosened it to adjust it and no change at all. Still 0. I am going to put a new one in tomorrow.

 

I have noticed now that this lack of power only happens after driving for about 45 minutes. For the first 30-45 minutes it runs perfect.

 

?????

So I put a new tps in it and same thing. Runs fine for a while then goes bad. Tps is now at zero and non responsive

some sensors require a 5v reference I think - maybe something is killing that line after it gets hot?

Well, after taking it to a mechanic buddy. I found out the motor has internal problems. When rpms go up there is a faint knocking sound. The knock sensor is picking it up and retarding the timing. I am pulling the motor to replace it. At least I had another motor already sitting in my shop.

i'd go with a new knock sensor first. They fail ALL THE TIME

 

These motors are consistently tappy sounding. No need getting scared off by what could be normal chatter of a subaru. 

Edited July 29, 20178 yr by AdventureSubaru

I did a new one knock sensor and it still did the same thing. Run fine for a while, then power loss. Swapped motor and all is well now. I used the intake (with knock sensor) from the old motor. Runs great and no power loss.

Today it started doing the same thing again. Apparently I hadn't driven it long enough since the motor swap. Now I'm stumped. New knock sensor, fuel filter and pump, plugs and wires. Not sure what to think now. Maybe ecu?

maybe some of the media in the cat conv is loose and blocking exhaust? vacuum gauge testing might be good - might spot a sticking valve too???

 

sure the feeling of power loss isn't a sticking brake caliper or some other dirveline issue?

Edited August 2, 20178 yr by 1 Lucky Texan

I'm still suggesting mass air flow sensor. They are known for causing the engine to periodically become gutless and even stall out without throwing a code.

 

Intermittent fuel pump would be number 2 on my list. I chased one all over the place trying to find why it bogged down on hills until I could actually hear the pump whirring, then I knew for sure. They are cheap and easy to grab from a junkyard. I think $10 put me back on the road that time.

 

At least you know that first motor is good. Now you've got a spare.

Edited August 2, 20178 yr by AdventureSubaru

Fuel pump is new. Mas is cleaned, not new. Guess I could swap it out.

 

Shitty part is, car ran great for a couple days and I just finished moving to a new place with no shop, so I scrapped the other motor

1. Swap the MAF.

Www.car-part.com or post in parts wanted here.

 

2. When it does it again pull the fuel hose and crank. If it flows like a hose the pump is fine. If it trickles out you found your issue.

Update. Fuel pump flows great, maf swapped, still same problem.

 

I had a scanner hooked to it today and was watching live data while driving around. I (think) all looked well, but I no tires 1 thing odd. The line labeled fuel sys1 was bouncing back and forth between clsd and open1.

 

Does anyo me know if that is normal or should it stay one way or the other.

 

It would change all the time, car was comepletly warm and it would do it while I was giving it gas or not.

And also the line labeled abslt tps was at 0.0 again at idle. I had it set at .45 at idle to begin with.

?

Something is making the tps reset to 0.00 after driving for a bit. I have changed the tps and still does it

any chance of wiring damage from rodents or pinched by some work that was done?

I am about to pull the dash. Everything in the engine bay looks good. If I don't find bad wires in the dash then I am ordering the ecm