I've created this thread to highlight the most common fixes for any sort of 'Hesitation' issues commonly encountered with our Subarus. It seems many of us experience hesitation at some point in time and usually all for the same reasons.
Hesitation in this thread is defined as , but is not limited to : Throttle lag , Stumbling, and Bogging while the Engine is 'Under load'.
This hesitation may, or may not throw a CEL code. Most times, the hesitation is our 'early warning' of a part that is on it's way to failing,
and in a large majority of instances, no CEL's are thrown.
If you do get a CEL code, you can get them read at most auto parts stores.
(Auto Zone seems to be the popular choice.) Once you have a code, you can reference it here CEL Code Listing
**I have not arranged these 'solutions' in any particular order.**
Also : Most of these solutions will remedy hesitation problems at IDLE as well.
Common fixes for hesitation issues.
Coil Pack (non-turbo)
Coil Packs (for turboed cars)
Spark Plug Wires (non-turbo)
Valve cover gaskets & Spark plug tube gaskets (Do this if you find ANY OIL AT ALL on your Plug wire ends, or spark plugs or, if you see oil in the plug tube.)
Dirty Injectors (seafoam cleaner)
Dirty Throttle Body (seafoam cleaner)
Dirty Electrical contacts on MAF or MAP sensors (Simply use Electric contact cleaner on the contacts. Do any you can find really,
it's not bad for them.)
Dirty or failing MAF or MAP sensors
Blocked, Clogged, or 'on its way to failing' Catalytic Converter
Coolant temperature sensor
And occasionally : Bad Gas
Also commonly suggested, is improving the Grounding under the hood.
The following are common sensors that fail in regards to the transmission ; causing hesitation problems, as outlined above.
Throttle position sensor
2-4 brake duty solenoid
ATF temperature sensor
Line pressure duty solenoid
2-4 brake timing solenoid
Lock up Clutch (4eat)
Tourque Converter (4eat)
Valve Body (not sure how it works or fails, but can cause issues)
I will continue to update this thread as more information gets posted by you, the reader, or as new solutions to hesitation issues are found.
The somewhat sad irony of this thread is, I'm currently troubleshooting my own 'hesitation' issues, at this point, to no avail. My hope is that through my reasonable diligence, that others don't have to go through all these steps as I have.
If you have a solution to hesitation that you do not see posted, please post and I will add it. If you have links to DIY threads, or any other technical resources that relate, please post them and I will add them.
Thanks everyone! And Good Luck on clearing up your hesitation issues!