My mudwagon, a 1990 subaru loyale had one 02 sensor before the cat. My dad dropped the exhaust out of the car and pulled the single wire out of the sensor so I just left it out. Now the car is a lot weaker down low and almost dies when taking off from a stop. I did a lot of changes at once (homemade snorkel, hood exit "stack" type open header exhaust) so I don't want to go through the trouble of buying a new o2 sensor$$$ and welding a bung on my exhaust if it really doesn't matter on obd0 car. I'm thinking the open exhaust and the free flowing intake might just be too much for the ecu to handle.

The ECU should handle better air flow and bigger exhaust, but if you pull the O2 sensor, your gonna put it in limp mode and it will run like crap. Welding on a O2 bung doesn't take too much to do, especially if you can weld yourself.

 

Your loss of low end power could be because of the bigger exhaust, but I'd fix the O2 sensor before making any more assumptions.

 

Do you have pics of your exhaust? I thought about turning the exhaust tubes straight up right behind the head, which would go right into two cherry bombs and exit out the hood..Is that what you did?

I don't weld but I have a few welders in my area that will work for me for free. I just don't have the o2 sensor. Is the loyale as picky about aftermarket sensors as the newer models? Anyone have one I could buy?

oh and I bought 2 mandrel bent 1.5" 90 degree bends and a Y pipe with 2 1.5" inlets and a 2" outlet. Then I ran a single 2" pipe out of my hood. I am working on the picture. The exhaust is out of the car right now.

i installed the $20 bosch one on my 88 spfi. worked just fine. MPG went from 19 to 24 and it ran better (power wise)

 

the spfi ecu's are pretty primative in fuel injection terms but they do work, are reliable and need the exhaust oxygen content feedback to calculate mix. without it hooked up, it goes full rich to save itself. this can foul your spark plugs prematurely and cause loss of power due to almost "flooding" the mix out.

Edited June 3, 201114 yr by Ricearu

Here is what I have. Nothing fancy, but it works. Guess I'll put the bung right after the Y. Picked up the o2 sensor. Just have to hunt down a bung.

Take the O2 to a hardware store and find a nut it threads into. Bam. instant O2 bung.

ER27's run perfectly fine without an O2 sensor, i've put tons of miles on them like that. given the similarity with EA82's i would think they run fine without them too.

 

i've never heard of aftermarket issues with the older gen vehicles. the cheap stuff should be fine.

The O2 is used for part-throttle cruise, and idle. It cannot be used for WOT, or acceleration. Just the nature of the sensor. It will throw a code and can cause the ECU to do funny things as it goes into "limp mode" when it experiences failures. The system can never enter closed-loop operation with a bad or missing O2. Your mileage will decrese in a big way..... long story short - use the O2 sensor. A replacement single-wire unit is only about $25

 

GD

Oh man.

That's Demo Derby exhaust. I've got to show this to Mike and John. Mike wants to derby my FWD wagon. John takes a SBC and transfers it Ford, Dodge, whatever. Smashes them up. Repeat.

 

I want to hear it.

All you need now is a chrome rain flap:grin:

 

 

In all seriousness is it VERY important both for mileage and performance.

Edited June 4, 201114 yr by Crazyeights

Haha! I have a tractor flap but mine is grey.

Typically on Subarus, if its there, it needs it.