Sluggish Forester Revisited

[cloud dreamer]

Hi all,

I asked about a sluggish '01 Forester last month and tried the
suggestions. I also had it into Subaru yesterday and got the plugs and
wires changed. A misfire in one of the cylinders developed in the
meantime (the car was rocking at stop lights). The work seems to have
stopped that problem but the original remains. The biggest thing right
now is the loss of power on the highway.

After I go about 30 km or so, the car will accelerate on its own and/or
lose power only to catch after I've slowed about 5 or 10 kph. When I'm
losing power, I can tap on the accelerator and get no response right
away most times. The change in acceleration is enough to jerk me forward
or back in the seat.

I tried the fuel system cleaner. I've also added basic fuel injector
cleaner into the tank on every second fill. It seems to be better when
the cleaner is in the fuel.

Any ideas? I'm going back to Subaru on Monday but their engine scan
yesterday only picked up the misfiring cylinder.

TIA!

..

 

[Edward Hayes]

I'm a bit confused about this happing after 20km of driving. My first
suspicion would be that the knock sensor is retarding the ignition
timing for a short time. I would reset the engine control module
(ECU), by disconnecting the negative battery terminal and press the
brake peddle several times to discharge the unit and reset the default
parameters. If that doesn't help, change the fuel filter and then the
bigger $ in the MAS or is it the ? sensor. Ed

 

[cloud dreamer]

I'm a bit confused about this happing after 20km of driving. My first
suspicion would be that the knock sensor is retarding the ignition
timing for a short time. I would reset the engine control module
(ECU), by disconnecting the negative battery terminal and press the
brake peddle several times to discharge the unit and reset the default
parameters. If that doesn't help, change the fuel filter and then the
bigger $ in the MAS or is it the ? sensor. Ed

Yeah, except for the bit of sluggishness after starting, the surging
doesn't start immediately - always on the far end of my trip (I travel
40 km on the highway to get into town). I also notice that the surging
can continue for the rest of that trip but not always on the return trip
(after the car has been turned off).

The fuel filter was changed 22,000 km (and 14 months) ago. Could that be
the problem so soon after replacement? Faulty filter perhaps?

Or is a sticking injector possible? (I can also hear some rapid (valve?)
tapping when I'm going uphill - not loud, but noticeable).

Thanks!

..

 

[Funkadyleik Spynwhanker]

Didja check for O2 sensor function?

It can do all sort's of weird stuff if it is failing / has failed.
Including the stuff you are describing.

It does NOT always throw a code when it goes bad (which is how I know all
this stuff, driving around a while with it bad).

 

[cloud dreamer]

Didja check for O2 sensor function?

It can do all sort's of weird stuff if it is failing / has failed.
Including the stuff you are describing.

It does NOT always throw a code when it goes bad (which is how I know all
this stuff, driving around a while with it bad).

The tech mentioned that and probably got sidetracked by the misfired
cylinder which did show up on the scan. I'll ask them to check it. Thanks.

..

 

[Carl 1 Lucky Texan]

The tech mentioned that and probably got sidetracked by the misfired
cylinder which did show up on the scan. I'll ask them to check it. Thanks.

..

I forgot, is this an auto-tranny? NMaybe a good power flush of the
tranny will clean some gumminess outta some valve seats or something?
Also, have you noticed ANY 'jerkiness' making sharp turns/maneuvering in
parking lots?


Carl

 

[cloud dreamer]

I forgot, is this an auto-tranny? NMaybe a good power flush of the
tranny will clean some gumminess outta some valve seats or something?
Also, have you noticed ANY 'jerkiness' making sharp turns/maneuvering in
parking lots?


Carl

Yes, it's an auto. Wasn't sure if they still did power flushes. I had
one done to my Golf years ago, and it made quite the difference. I
haven't noticed any jerkiness making turns and that, but the
sluggishness when I first start it can get a little jerky as it takes a
second or two for the engine to respond to my foot on the pedal. Also,
the shift between power loss and sudden acceleration on the highway can
definitely be classified as jerky. (It's a wonder there isn't an imprint
of my nose on the steering wheel

..

 

[Carl 1 Lucky Texan]

Yes, it's an auto. Wasn't sure if they still did power flushes. I had
one done to my Golf years ago, and it made quite the difference. I
haven't noticed any jerkiness making turns and that, but the
sluggishness when I first start it can get a little jerky as it takes a
second or two for the engine to respond to my foot on the pedal. Also,
the shift between power loss and sudden acceleration on the highway can
definitely be classified as jerky. (It's a wonder there isn't an imprint
of my nose on the steering wheel

..

I suggest this COULD be a transmission problem. Many folks have had good
results from multiple drain/refill drive/repeat - type sequences (3-5
times) or 'power flushes'.

Carl

 

[Funkadyleik Spynwhanker]

I suggest this COULD be a transmission problem. Many folks have had good
results from multiple drain/refill drive/repeat - type sequences (3-5
times) or 'power flushes'.

Carl


--

Good point. If you haven't had it flushed it's about time anyway.

 

[cloud dreamer]

Good point. If you haven't had it flushed it's about time anyway.

I look to get it done on Monday.

My only other question is: if it's happens to be a failing oxygen
sensor, what happens if it fails altogether? Will I find myself on the
side of the highway testing out my new cell phone?

Thanks!

..

 

[Carl 1 Lucky Texan]

I look to get it done on Monday.

My only other question is: if it's happens to be a failing oxygen
sensor, what happens if it fails altogether? Will I find myself on the
side of the highway testing out my new cell phone?

Thanks!

..

They usaully get 'lazy' first before failing completely. That's not to
say a connectoer or wire isn't about to come loose. Plus, you would
likely get some kind of diagnostic code indicating the O2 sensor after
the CEL came on. I suspect the ECU would go into 'limp home' mode and
default to the factory emergency map and you'd likely be able to at
least drive to a safe place if not home or to a mechanic. Not sure.

Carl

 

[cloud dreamer]

Carl 1 Lucky Texan wrote:

They usaully get 'lazy' first before failing completely. That's not to
say a connectoer or wire isn't about to come loose. Plus, you would
likely get some kind of diagnostic code indicating the O2 sensor after
the CEL came on. I suspect the ECU would go into 'limp home' mode and
default to the factory emergency map and you'd likely be able to at
least drive to a safe place if not home or to a mechanic. Not sure.

T'was the O2 sensor after all. They put in a new one today and so far
it's riding perfectly.

Thanks all for the info!

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