Engine stumbles on accel. at low rpm....

[idahosubaru]

Hello everyone. I'm new to the forum. I have a 2003 Legacy L, sedan, 2.5L, non-turbo. It has 221k miles on it (daily driver).

Recently my Subaru started having difficulty accelerating from low rpm. This is most noticeable when starting from a complete stop or shifting when I end up near 2,300 rpm in the next gear. I had a P0065 code a few months ago with no change in performance at the time, so I deleted the code. I checked the injector air assist valve. It was dirty, so I cleaned it and checked the solenoid against the battery. Nice solid clicking in the valve during the battery test. No other codes are being displayed.

In the last year I have replaced the following:

1. IAC
2. Upstream O2
3. Valve cover gaskets
4. Front CV Axles

I am getting ready to replace the clutch, timing belt and water pump. Should be a fun weekend.

Does anyone have any ideas of what could be going wrong?

 

[Ozark_SyntheticsLLC]

First off Welcome to the forum. I hope you find some very helpful information here.

2nd.
The P0065 code you received earlier is more than likely the cause of the difficulty of acceleration with your 2003 Subaru Legacy. I understand you cleaned it and checked it and heard the solenoid clicking. Typically once that code appears it means that the valve is on its last leg and should be replaced. I have been fooled before as well with a good strong click sound while testing a solenoid. They can cause this condition but not give a code until they completely fail.
Some other items that might be causing the issue:
- Clogged fuel filter
- Dirty MAF sensor at the air intake
- Dirty butterfly valve at the air intake

That is my two cents on it, good luck with the clutch, timing belt, and water pump.

 

[idahosubaru]

Well, I replaced the injector air assist valve and the fuel filter. No change. Going to the fuel pump next unless someone has advice to the contrary.

 

[idahosubaru]

I’ll clean the butterfly. This model runs a MAP sensor. No MAF (unless I’m completely blind and it’s running both).

 

[idahosubaru]

Almost done with the timing belt....

 

[Ozark_SyntheticsLLC]

Did you finish.

 

[idahosubaru]

Yep. Timing belt done. Also replace the fuel pump.

Still has the stumble. I'm running out of options. Could be dirty injectors. I'm going to try and run a bunch of Seafoam through it...

 

[idahosubaru]

Also replaced the water pump while I was in there.

 

[Ozark_SyntheticsLLC]

Did the Seafoam get it to work?

 

[idahosubaru]

Negative on the Seafoam.
Replaced the PCV valve. No change.
Might be time to pay someone for some diagnostics. *sigh*

 

[Ozark_SyntheticsLLC]

*sigh* I think you are going to have to pay someone for some diagnostics, unfortunately.