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Loss of engine power on Forester


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This happened to me earlier; it went from relatively minor loss of power earlier to now no power to go up hills; 2002 Forester will idle, but very little power.  I checked previous mentions of something similar and one owner said that changing the O2 sensor in front helped him.  I tried to jack the car up earlier roadside and found the forward O2 sensor but did not see how to de couple it if that would help.  Also thought low gas might be an issue so added a gallon, no change.  

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2 hours ago, ThosL said:

This happened to me earlier; it went from relatively minor loss of power earlier to now no power to go up hills; 2002 Forester will idle, but very little power.  I checked previous mentions of something similar and one owner said that changing the O2 sensor in front helped him.  I tried to jack the car up earlier roadside and found the forward O2 sensor but did not see how to de couple it if that would help.  Also thought low gas might be an issue so added a gallon, no change.  

Is this a daily driver? Any other symptoms? Original engine? Has it been sitting for long periods of time? recent maintenance? other recent issues or parts replaced?

 

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any CEL codes? Codes can usually point you to problems.

what did you use for plugs & wires?  should be standard copper core NGK plugs with proper gap, and either NGK or OE wires - anything else is garbage.
why, specifically, did you replace the coil pak? unless there are obvious/apparent problems, it is rare to need to replace that.

with all the older Subarus I have had, I have never needed to replace a cat converter - and pretty much every one of them was pushing the 300K mark when i passed them on...
O2 sensor, yeah.. but never the cat. Would be interested in knowing why it was replaced.

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Most of the electrical replacement parts were OE; previous owner replaced the cat. converter; one friend's high level mechanic said it could be cat. converter being clogged. Coil breakdown happened a few months ago and was replaced by mechanic.

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It was throwing the code on the downstream sensor; don't have device to check it at this point.  What would be the symptoms of the upstream O2 sensor messing it up or the cat converter being clogged?

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1. Read the check engine codes. It could have a pending code even if the check engine light isn’t lit

2. Guessing is a good way to waste time

3. Speaking of guessing how old are the plugs and wires?

4. Are the plugs and wires OEM or NGK?

5. Pull the plugs and look for oil on the *external* part of the plugs/wires  

Misfire is more likely than O2 sensor. 

Symptoms vary and overlap.  Clogged converter will get hot snd turn red. You may smell a burning type smell.  Disconnect and drop the exhaust and see if it runs better but then again yours is likely rusty and problematic to remove.

90s EJ knock sensors crack all the time - by far the single most common sensor to cause problems. I’d pull the knock sensor (12mm bolt) on your Forster and see if it has signs of cracking on the base of it.

O2 sensor - follow the wire up from it until you see the connector. It’s usually on the passengers side by the frame rail or axle.  Of course you know they’re usually corroded rusted and hellacious to remove. 

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20 minutes ago, NV Zeno said:

Try replacing the fuel filter.  Cheap and easy.

For Subaru's particularly that new it has a very very small chance of being the issue.  It is cheap and easy it's just not going to fix his car.   He can pull the outlet side and see the fuel flow through it into a cup when turning the key to "test" if it's working.  It should pour out roughly like a garden hose. 

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Thanks for the advice; a friend over an hour away said he'd try to help me on this, as this is a white collar town hardly any do it yourself mechanics, and people have been avoiding one another during the pandemic.

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1 hour ago, ThosL said:

codes that came up, were PO452; 073; 1443; 0420 and 0031.  The cat code I knew about, not sure what is going on with the others.

1443 and 0420 are not causing the no start. 

0452 I’m not familiar with. I think it’s emissions related and I’d be concerned about a rusty tank bleeding off pressure (and vapors). But I’m unsure. 

0031 are front O2 sensor codes.  Check wiring for damage, FSM for how to test or many people just replace it and see  

On older vehicles you can just disconnect the O2 sensor as a test to see if it runs better.  if it does then that almost confirms the O2 sensor is the issue   Not sure if you can still do that with an 02 but I’d try it and see what happens   Worse case…what…it doesn’t start?  Haha who cares, it already doesn’t start  !

 

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i know the rear O2 has pretty much zero effect on running.. front, not sure..
my 02 Foz had a code for the rear O2 (broken wires - bought one but never got around to installing.. car ran fine)

1443 and 0452 are both evap emissions related, and probably have very little to do with much of anything.. on mine, there was a solenoid just above the charcoal canister (rear of car, behind RR tire area) that solenoid was completely nonfunctional but the car ran fine.. never bothered to replace it because rusty nightmare.

Would start with that front O2 sensor - leave everything else alone for the time being..

Knock sensor is not a bad idea, either.. they can quite often be bad and never throw a code.. has happened to me

and 073?? there has to be a digit missing.. there is no such number listed in the FSM for 2002 Forester, nor is there a 0073 or 0730... so... yeah... please double check that one.

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I may have left out the letters assuming that they were PO; PO452; PO73; P1443;PO0031

My friend assumed that it was the transmission fluid being low so we got a couple quarts but that didn't make any difference.  It may be a tow through AAA now to a mechanic who is better at diagnostics.  

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1 hour ago, ThosL said:

I may have left out the letters assuming that they were PO; PO452; PO73; P1443;PO0031

My friend assumed that it was the transmission fluid being low so we got a couple quarts but that didn't make any difference.  It may be a tow through AAA now to a mechanic who is better at diagnostics.  

all codes will be a letter and FOUR digits, not 3
so the P073 is missing something, somewhere.

and yeah, P07xx codes tend to relate to either brakes or tranny.. but you are STILL missing a digit

 

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We checked out the forward O2 sensor and when getting the breather apparatus off saw that the plug was disconnected anyway with a zip tie holding up the O2 from the cat converter end.  I decided to have AAA tow it to a mechanic so will let them figure it out.

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A friend cleared the codes and then other codes did not come back, but the battery was low he said so not sure.

Towed the car to a shop who said he would let me know tomorrow.  I spoke to the previous owner who called me out of the blue today.

The shop where it was towed said it may be the timing belt jumped.

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Used to be a guy named Angelo who was off East Ave in Norwalk , pretty easy to you. But I was just down that way and asking around and can’t confirm he’s still around there. He’s a former or maybe current dealer tech. He worked at Dwan , and I think another local old Subaru dealer. 
 

Sorry this doesn’t put a connection in place but do keep an eye out for him. He’s probably around 55-60 years old now. 

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