Cat and 02 sensor question

[desertsubaru]

Over the winter My rear cat converter rusted off, Being out of work I couldn't afford to get one welded back in. A buddy of mine did weld a piece of pipe with the bunghole for the 02 sensor. My question is will the rear 02 sensor work right without the cat to heat it up? I plan on getting a cat as soon as I get some money but for now my gas mileage is horrible, maybe 12 MPG on the highway. If I wanted to add a heater resistor until I can get a cat which color wire would be the heater wire?

[idosubaru]

install the rear O2 and see what happens? do you just have an open hole there right now and the sensor isn't installed? at 12mpg you're loosing far more than the cost to repair it right, so i'd do whatever you need to.

 

should be able to weld an aftermarket converter in (they're much cheaper).

[johnceggleston]

should be able to weld an aftermarket converter in (they're much cheaper).

 

depending on what rusted out, you mat be able to weld the original cat back in place.

[desertsubaru]

install the rear O2 and see what happens? do you just have an open hole there right now and the sensor isn't installed? at 12mpg you're loosing far more than the cost to repair it right, so i'd do whatever you need to.

 

should be able to weld an aftermarket converter in (they're much cheaper).

Yes I put the O2 sensor in the Bunghole I had welded in place. The original cat not only rusted out but was bad to. Trust me If I could get the money up to have one welded in I would but I have been out of work for a while living on employment insurance. I only use the car to goto the store and back, about a 20 mile round trip so I only fill up about once a month. I have an OEM o2 sensor on the way from a board member because mine tested bad.

I need to know though if the o2 sensor operates at a certain temp to work properly. I know with out the cat that it will be a lot cooler and have read that other brands of cars need it to be very hot.

I have some heater resistors from a project car I had years ago I never used that are made to fool the ecu into detecting the o2 sensor is hot enough but don't know which wire is the heater wire on the 96 OB rear sensor if it has a heater wire that is. It has new plugs,wires, and air filter. The old plugs were the proper color they should be but the inside of my tail pipe is black.

This car was an original 2.5 that I swapped a 2.2 from a 95 into that only has about 80 k on it. It idles fine and runs fine at acceleration and at speed but sucks gas.

[hankosolder2]

The rear 02 sensor shouldn't have any effect on your gas mileage. It's simply there to verify the proper functioning of the catalytic converter and set a check engine light in the event of a faulty cat.

 

I'd check the coolant temp sensor (if it has failed, it's like driving a carburated car with the choke on!) and the front 02 sensor. You could also have dribbling injectors or a faulty fuel pressure regulator.

 

Good luck with both the car and the job market.

 

Nathan

[desertsubaru]

When I had it tested the codes came up for rear o2 sensor,EGR and Knock sensor I replaced with one I had. Would the temp sensor show in codes? The block didn't have the place to screw the egr pipe into so I just removed the egr and put a plate over it.

[hankosolder2]

A bad Knock sensor could cause poor MPG -is that code still there with the replacement sensor?

 

A faulty coolant temp sensor won't necessarily throw a code.

 

 

Nathan

[desertsubaru]

I will get it tested this week to see what codes are coming up now then will report back to you.