Subaru Impreza Projects, Tips, and Tricks

Welcome to my Subaru Impreza page. This is where I will discuss the various Subaru projects and upgrades that I plan on doing myself on my Outback Sport.

 Install a WRX Muffler on a Subaru Impreza Non Turbo

This morning I picked up a WRX muffler on Craigslist so I could put it on non turbo, NA Subaru Impreza. I was under the impression that this was a direct bolt on with no modifications and I was wrong. My car and the muffler were supposed to be 2002. They looked very close but it wouldn't bolt up. Take a look at the first two pictures below for a muffler comparison. I wanted that muffler on there and after fitting the WRX muffler on I was able to see how to get it to bolt without taking both to a muffler shop. On of the problems is that the non-turbo muffler (NA) has a 1.8" ID measurement and the WRX measures 2.25". I started my alterations by trying to open up the new flange holes but that was no going to work. I next re-fit the WRX muffler back into place and marked the new flange where I could cut to give access to the smaller flange bolt spacing. The result was a little ugly but it bolts together and sounds good. It has a little low end rumble on start up and just above idle but goes away under acceleration. I think I want to replace the gasket with a larger one to make sure it is sealed correctly but so far so good. Check out the pictures.
02' WRX Muffler next to NA Muffler

NA Exhaust Gasket on top of WRX Flange
Twin Tip WRX Muffler on NA Impreza

WRX Muffler Flange Alteration and Pipe Size Difference

 Find Part Numbers and Pictures for Your Subaru

I was searching Google and forum sites last week trying to track down some parts number for WRX exhaust system that I got off of Craigslist. I came across a great and easy to sue site that got me pictures of what I was looking for with part numbers. I was trying to track down the exhaust system parts for a 2007 and higher Subaru Impreza WRX. This exhaust came with dual twin tip mufflers which I thought were rather common on WRX's but they are not.

Here is the link to that great Subaru parts website:

Here are pictures of that WRX exhaust system I have:

2007 Subaru Impreza WRX Twin Tip Mufflers

2007 WRX Downpipe

2007 WRX Resonator Tube

Subaru Impreza 2.5 Homemade DIY Cold Air Intake

I have seen some other folks do this with their Subaru's on other forums but no one actually provided sizes and what to buy. So here goes my post on how to build you own homemade cold air intake for a 2002 Subaru Impreza Outback Sport 2.5. Here are the items I purchased (prices rounded up):
  • 2 Feet of 3" ABS Pipe - $8.50
  • (1) 3" ABS 45 Degree Elbow - $4.00
  • (1) 3" x 2" Flexible Coupling (rubber with two clamps) - $6.75
That is it for parts, now here are some instructions on making it happen. This only took me about twenty minutes to do.
  1. First remove all air box components down line of the filter box.
  2. Cut two pieces of ABS pipe. One piece at 3.25" long and the other at 15.375" long.
  3. The rubber flexible coupling goes on next but I needed to use a heat gun on the 2" end to get it to stretch over my filter box snout.
  4. The best way I was able to fit this into place was to assembly the long piece of pipe to the elbow and then the stub piece into the other end of the elbow. 
  5. Next install the stub end into the 3" end of the with the long part facing up.
  6. Once installed firmly into the flexible coupler, rotate down and flex the air box assembly some to get the other end of the abs pipe into the fender well opening.
  7. I disconnected my battery to reset the computer and then took my car for a spin.
I will give and update when I get some more miles in on this upgrade. I did this because I lost half of my factory air intake components. Check out some pictures:
DIY Cold Air Intake Subaru Impreza 2.5, Homemade
3" x 2" Rubber Flexible Coupler

Knock Sensor was bad on my 2002 Subaru Impreza

About three weeks ago my Subaru started getting terrible gas mileage and was running like crap. The next day my check engine light finally came on and I drove my car to Auto Zone. They pulled my engine codes and it showed that there was a faulty knock sensor. Auto Zone did not have it in stock and the dealer wanted $110 for there sensor. I called the local Napa and they had one on hand for $90 so I went with that one. When I pulled the old sensor I immediately saw the problem. The old sensor had two cracks in the plastic housing and the wire was frayed as well. The old sensor came out real easy but the new one was a pain in the but to get back on. I recommend taking a digital picture of the location of the knew where it went but forgot how the wire routed through the other components to lay perfectly in place while I tried to lower the bolt into position. Once everything was back on I restarted the car but the light was still on. I drove the car some and then stopped it and and shut the engine off. I restarted it and the light was gone. I still believe that I need to disconnect the battery to allow the computer to completely reset itself to take full advantage of the new sensor.

Replacing a separated harmonic balancer, Subaru Impreza 2.5

Today I was listening to my engine with the hood open while running. I reached down to manually move the gas linkage to "blip" the throttle and watched as one part of the harmonic balancer moved back and forth on the inner piece that was attached to the crankshaft. I just about crapped my pants in amazement and then quickly shut the engine down to go and find parts. Your H.B. is never supposed to move under any circumstances except in a circle as it was intended to move. My engine started getting noisy about two weeks ago and I assumed it was my AC compressor since it made that noise when I turned the AC on. Lucky for me we have a Napa warehouse in town tat was open on Sunday and they stocked the H.B. The next trick was removing the old H.B. Apparently there is a special tool that you can rent to hold the H.B. while you apply lots of torque to the 22mm head head bolt that keeps the H.B. on the end of the crankshaft. I however consulted Google and YouTube for inspiration on how to remove my old parts. Everyone said to put your breaker bar on the H.B. screw (22mm), lock it down on the frame of the car, remove the connector for the coil pack and crank the engine a few shorts turns to loosen the screw. My breaker bar was too short to reach the frame so I tried to lock it to the upper part of the engine and it worked great!. I was able to brace it up against the steel bracket for the AC tension system. I then placed two C-clamps around the breaker bar end to retain it if it broke loose and went crazy on me. I also bungee'd the end of the breaker bar so it would not rattle around. I cranks the engine over two short turns after removing the center coil pack connector and to my amazement it worked great. Here is a picture of the set up.

2.5 Subaru Engine Balancer Removal
Subaru Balancer Removal Set Up

2002 Subaru Impreza Fuel Filter Replacement

A+A+ all the way to Subaru's engineers for making the fuel filter easy to replace on their 2.5 engines in the Impreza. The filter is located on the driver's side near the shock tower. It has an easy manually operated clamp that holds the body of the filter in place. The fuel line hoses are standard old fashioned rubber fuel hoses with standard hose clamps. That was a shock! Where are all of those fancy clips and special tools needed to disengage the high pressure fuel lines? Filter cost me $22.00 and I was done replacing the filter in 15 minutes. I remember some of my other fuel injected vehicles with the fuel filter underneath the car, trapped behind the gas tank, and who knows where else. Nice job Subaru!