[selkie]

I've read quite a few threads here about Subarus with similar problems but sadly, I have yet to find a solution for my Subaru. I have a 2002 Forester S with 148,000 miles. Recently, I took it in for an oil change and mentioned to my mechanic that there was an intermittent slight hesitation/skipping sensation that felt like a fuel issue of some kind. There were no CEL codes at the time.

He changed the oil, spark plugs and wires and installed a new fuel pump. Ironically, the problem got much worse at that point and the car began lurching and hesitating like a crazy. He was unable to find the cause of the lurching. Eventually, I did get a check engine light that indicated there may be a problem with the oxygen sensor, but he performed the test where you remove the sensor and the car did not improve at all. The check engine light mysteriously vanished and has not returned, and there have been no other codes. The catalytic converters and oxygen sensors were replaced just four years ago.

He suggested that I take it to another mechanic who was also unable to find the source of the problem. I am now back at the first mechanic's shop and he is absolutely stymied. The car is particularly sluggish going uphill and when I have to make frequent traffic stops. Even at speeds over 50, it alternately surges and hesitates as though one were stepping on the gas and then brakes and has recently started backfiring occasionally.

Last night I drove it for about 15 minutes and then stopped for a few minutes at which point the car would not start and it did not even turn over - totally silent. I left it for a few hours and when I returned to check and see if the lights were working, it roared to life and I was able to drive it home, which was less than a block away. This morning I started it several times but did not attempt to go anyplace.

These problems have been dragging on for at least 6 weeks and I am at my wit's end and am getting cabin fever.

Any suggestions as to how this problem may be solved short of hoping a giant tree or boulder crush it to oblivion?

 

[bman400]

Sounds like a plugged fuel filter. New fuel pump made it worse, as its pumping harder than the old pump. It's probably worse when you push the engine harder to pick up speed, go up hills etc....

 

[gghbi]

This sounds a lot like a problem I just came on here to investigate. My 2003 Forester (2.5 natural aspiration) with 242000 miles showed some of these signs several months ago, and I suspected the fuel filter and replaced it. Recently it has gotten worse and seems to manifest itself when the car is warmed up, and when going up a slight to moderate hill. It has the same problem that it alternately surges and hesitates as though one were stepping on the gas and then brakes and sometimes backfires. It loses throttle response as well when throwing these fits.

I am seeing the PO420 cat converter and O2 sensor codes, but I am not sure if these are not just due to the misfiring problem and not a useful clue. Since it seems like it is running out of fuel, I was wondering if the fuel intake screen might be fouled, if the fuel pump is failing or overheating, or if the problem is back in the cat with obstruction there since it most often occurs going up hill.:|

Any wisdom from the collective brains on here will be appreciated. I have a limited budget and need to be selective on finding a fix. I also need to evaluate how effective the fix will be in terms of the high mileage and expected lifetime of the car. (I know it is a good car and could go well over 250k, but not sure how far)

 

[bman400]

gghbi,

Since you have already replaced the fuel filter, and given the P0420 code, sounds more like a plugged or partially plugged Cat converter.