'01 Legacy won't rev over 1,000

[FreeLegacy]

Hello folks,

 

I have an issue that has our mechanic stumped.  The car is an '01 Legacy wagon with 147,000 miles.  Automatic. 

 

The problem started on March 19th. (Prior to that the car was fine.)  I drove my son to school, as usual.  A ten-minute drive through typical suburban streets, 25-35 mph, stop signs and stop lights.  On the way there, it would rev fine to about 2,000, maybe 30 mph.  When trying to accelerate further, the customary pressure on the pedal did not produce the usual increase in revs and speed.  It took longer to get up to 3,000 and about 40 mph. 

 

On the drive back it got worse until about 5 minutes later (15 minutes of continuous running,)  It wouldn't rev above 1,000 and would just crawl (or limp?) along at perhaps 2 mph. 

 

I decided to tough it out and drive it to our mechanic, a Marathon dealer.  Took about 30 minutes to make a 5 minute trip.

 

His first thought was timing belt but he's checked that and ruled that out.

 

His next thought was an exhaust blockage but he dropped the exhaust and has since ruled that out. 

 

I talked to him yesterday (3/25) and he was stumped.  His next thought was to do a compression test, although he didn't think that would show much since it reved so well at low revs. 

 

So I wonder what folks here might think?  I haven't found much from googling or searching here, but I did find a thread that referenced limp mode for '05 Outbacks.  Not sure if the Legacies have that.  Found another reference to check the fuel pressure, and I might mention that, but I'll bet he's already thought of anything I might find on the internet.  With the possible exception of something unique to Subarus. 

 

Not much recent work.  A couple of months ago I replaced the coil to solve a problem of not wanting to start when raining.  Other that that, it recently had an oil change and transmission fluid change (but not a flush.)

 

The check engine light has been on for...um...some months.  I had the code read some months ago at an Advance Auto Parts and they came up with PO420.  I have been meaning to address it but the car ran fine (until the 19th) so I kept forgetting. 

 

Thank you for any suggestions.

 

Dave

[Gloyale]

Check the throttle cable adjustment

[Fairtax4me]

My first guess would be the cats are plugged. Did he unbolt the header from the engine?

P0420 code means some condition is happening and the computer thinks the cats are not working properly. The causes for this code vary widely, but generally if the code comes on, there is potential for the cats to get overheated and melt which will cause them to clog up. It's better to address a P0420 sooner rather than later because of its potential to cause costly replacement of the cats.

 

Timing could be an issue but that typically causes a rough/shaky feeling because it will create a misfire condition.

[Aluxes]

Oil pressure? I had an old Buick and the oil pump seized, there was no knocking or noises to indicate no pressure. Same symptom as you. Wouldnt rev, could only drive about 2 mph. Took it to friends shop. It took a while but we found a chunk of metal had got past the pickup screen and seized the pump. We replaced it and the car ran better than ever. Just a thought. Good luck.

[forester2002s]

Blocked fuel filter?

[86 Wonder Wedge]

Could also be a crank sensor dying... Or a MAF/TPS issue? I'd check for nasty vac leaks too.

[ocei77]

I agree with FairTax. Sounds like a clogged cat.  Had a similar issue with my 07. Ran rich for too long with a P0420. The second cat was clogged, not the first. Have your mechanic separate the exhaust between the two and see if it revs freely.

If so, you'll also need to replace the first O2 sensor as it controls your AF ratio .

 

O.