10 replies to this topic

[sanfelice]

Hi, all. Question: anyone know why my ride (2000 VR) would have both O2 sensors mounted before the cat on a custom system? Car has EST pipes and a CJ converter and custom downpipe, all installed by previous owner. I've had the car for about a year.

why would the second O2 sensor be mounted in front of the cat? is this typical of the smaller CJ-style converters? or, is it a mistake?

[mune237]

CJ converter? Never heard of that. How would that work? Both 02s would have the same readings, and with that, you should have a CEL on, cause it would think the cat is not functioning???????????

[fischmama]

You may have a tune that will ignore the rear O2, the only reason it is still there is to not have a check engine light for the heater circuit.

Just a thought.

[Boglin]

Sounds like o2 delete and they put a o2 where your AFR or pyro should go? Any CEL's? if not I'd say thats probaly what happened...

[NEU]

I have the original '00 AWD downpipe that CJ did for John Sharp. It sounds like the previous owner installed the cat backwards, it should have the O2 in the cat down stream of it. If they installed it backwards that would be in front of the cat. Undo the clamps and flip it. Should get rid of the CEL you've got too.

[P0RTER]

I have the original '00 AWD downpipe that CJ did for John Sharp. It sounds like the previous owner installed the cat backwards, it should have the O2 in the cat down stream of it. If they installed it backwards that would be in front of the cat. Undo the clamps and flip it. Should get rid of the CEL you've got too.

That's what I was thinking, that should work assuming that doesn't put the bung out of reach of the O2 sensor.

[sanfelice]

That's what I was thinking, that should work assuming that doesn't put the bung out of reach of the O2 sensor.

that's pretty much what will happen... can't figure it out.

I'm going to get the muffler place (custom place) to flip it and see if that cures the problem.

very strangely, I was not getting any CELs until recently, after driving the car for a year.

I'm going to get the muffler place (custom place) to flip it and see if that cures the problem.

I mean to add that the muffler shop will have to make a new bung somewhere as I don't see the wires reaching if the cat is flipped with the existing hole.

[mune237]

I had to get / use an 02 sensor wire extender

[NEU]

You have to extend the rear o2 sensor with CJ downpipe. New bung isn't going to solve the problem that the o2 leads need to be extended.

Unclamp the v clamps, flip it and extend the o2 lead and you're done. Anything else is just wasting money.

[ByTor]

I think you have two options here. The first is, if there is an additional bung after the cat, get an O2 extender wire, plug the 2nd O2 sensor into it, seal the bung it came out of and go merrily down the path of automotive happiness.
The 2nd option, if there is no bung and you are getting a CEL, is to use an extender - it is essentially a piece of pipe threaded to screw into a O2 bung on one end and tapped to accept an O2 sensor on the other - on the O2 sensor to get it out of the path and your CEL will go away. It is the 1st O2 sensor that matters - for adjusting the AF ratio.
Cost of the extender is $10 or less.
.

Edited by ByTor, 08 October 2012 - 02:41 AM.

[Tinaphps]

Hmmmm ... I'm going to have to think about that one