Questions re: O2 sensors & deleting 3rd cat

[98SF19]

I'm way overdue for new o2 sensors (been getting 200 miles per tank & exhaust STINKS!) and I'd like to have the 3rd cat removed, but I have questions:

1. As I understand it, each downstream sensor only serves to monitor the effectiveness of its respective cat, so by removing the 3rd cat, I won't need to worry about that o2 sensor any more. Is this right?

2. I came across a post by Doug Lewis (http://v8sho.com/SHO/P0420StillafterO2sensorsreplaced.htm) This post is about 7 years old, and in it, he says Ford was charging $2k PER CAT!! I found a bunch on the net that are MUCH less expensive, but it's not always easy to tell what's crap and what's not. Has anyone replaced theirs recently that could make a suggestion? Also, any suggestions for O2 sensors.

3. What's the best source for the flex pipe and necessary parts?

I'm in Brevard County, FL if anybody's interested in doing the work.

Thanks!

 

[lowc]

check out shosource.com they might have what your looking for

 

[dqdude]

As far as I know, the 3rd cat doesn't have an O2 sensor. My 97 didn't have the 3rd cat when purchased and I just replaced the 4 existing O2 sensors a few weeks ago and did not come across a connector for any other O2 sensors.

 

[newshofan]

Shosource does have a really nice magnaflow y-pipe that I would like to add myself eventually. And yes there is no o2 sensor on the third cat. Shosource may have some o2 sensors as well otherwise I would go with bosch as that's what most oem ones are anyways. Doug sells a third cat delete pipe at FPS.
I believe you will want some form of flex pipe on your exhaust as you want your pipes to be able to move a little. Another option you can do. Is gut out the third cat I was given that idea by a few other people on here. I havent done it yet but plan on it as soon as I feel like crawling under the car and messing with those dang bolts.

 

[alecracing]

I'm way overdue for new o2 sensors (been getting 200 miles per tank & exhaust STINKS!) and I'd like to have the 3rd cat removed, but I have questions:

1. As I understand it, each downstream sensor only serves to monitor the effectiveness of its respective cat, so by removing the 3rd cat, I won't need to worry about that o2 sensor any more. Is this right?

there is an upstream o2 sensor (before first cat) and a down stream o2 sensor (after first cat but before second cat). There is no downstream sensor AFTER the second cat so computer has no idea if its working so you should be able to remove thee third cat with no problem

2. I came across a post by Doug Lewis (http://v8sho.com/SHO/P0420StillafterO2sensorsreplaced.htm) This post is about 7 years old, and in it, he says Ford was charging $2k PER CAT!! I found a bunch on the net that are MUCH less expensive, but it's not always easy to tell what's crap and what's not. Has anyone replaced theirs recently that could make a suggestion? Also, any suggestions for O2 sensors.

3. What's the best source for the flex pipe and necessary parts?

I'm in Brevard County, FL if anybody's interested in doing the work.

Thanks!

:sun::sun::sun::sun::sun:

 

[98SF19]

Actually, there is one cat for each bank, front and rear, which each have a fore and aft sensor. These then join at a y-pipe, which connects to the 3rd cat. I.E. the first 2 run in parallel, not in-line, before meeting up.

Thanks for the replies - I must have misunderstood the O2 sensor configuration with the 3rd cat.

Being in a money crunch, I think I'll just gut the 3rd (have it taken out altogether at a later date) and get all new O2 sensors. I believe all 4 are originals! Like I said, way overdue. I'd still like to hear from somebody that's gone with aftermarkets, especially hi-flows.

Thanks again

 

[Mr Anonymous]

Clean your MAF before replacing O2's. That's more often the cause of mixture and driveability issues than O2 sensors.

 

[SHOZ123]

Don't change the post cat sensors. They only tell the PCM if the cats are working. There is no engine control connected to them.

The OEM O2s are NGK. FWIW

 

[98SF19]

Alright, I'm going to clean the MAF first before going with the O2 sensors. As far as this goes, I found a post from Doug from many years ago (http://v8sho.com/SHO/P0172BanksOneandTwo MAFCleaning201.htm look at the fourth post down) where he describes cleaning it. I have been using a K&N for years, so this might be it. Now I know Doug's the real deal, but I'd read somewhere else that the MAF was very sensitive and blow-drying with compressed air seems a bit . . . turbulent. I"m probably wrong, but I want to be sure.

Thanks

 

[SHOZ123]

On the V8 SHO MAF you can see the wires and if they have any fuzz built up on them. I just used contact cleaner and never had any issues.

 

[bacernate]

Instead of gutting the cat, if you can swing it buy the delete pipe and then take the cat to a recycler and they'll pay you 50-75 bucks for an oem cat.

 

[SHOZ123]

Hmm, I never got more than $15 for a primary cat. $5 for the third cat.

 

[ThatShoGuy]

Hmm, I never got more than $15 for a primary cat. $5 for the third cat.

they ripped you

i work in the cat biz and there are standards and pre's on a taurus

pres we buy for $17
standards we buy for $55 (3rd cat)
mind you prices change on cats every day

 

[98SF19]

recycling cats

I would imagine that when platinum's going for high dollar, that's the time to drop off your old cats. From a recycling perspective, would it matter whether or not you replace the 3rd cat with the flex? I may be showing my ignorance on the matter, but couldn't you remove the "guts" of the cat, cash that in, and still have the housing intact?

Since you said you're in the cat business, what would you recommend as either an oem or a high-flow replacement for the first 2 cats? Have I been completely brainwashed by Al Gore for even asking?

If I can get $50+ for a 3rd cat trade-in, that will put a dent in the cost of new ones.

 

[ThatShoGuy]

I would imagine that when platinum's going for high dollar, that's the time to drop off your old cats. From a recycling perspective, would it matter whether or not you replace the 3rd cat with the flex? I may be showing my ignorance on the matter, but couldn't you remove the "guts" of the cat, cash that in, and still have the housing intact?

Since you said you're in the cat business, what would you recommend as either an oem or a high-flow replacement for the first 2 cats? Have I been completely brainwashed by Al Gore for even asking?

If I can get $50+ for a 3rd cat trade-in, that will put a dent in the cost of new ones.

i should re-say that....

i work where we buy used cats..

i know the catalytic is not worth as much out of its housing.

 

[dlanes]

Just remove the 3rd cat no CEL. I had someone cut it off and weld in a new pipe for $20.

 

[BamSHO]

3rd cat gone, resontator gone, replace upstream O2s. No CEL. Mileage is decent as long as I keep my foot out of it.


Brian Michael
98 silver Gen3

 

[98SF19]

Milage

By decent, do you mean at least 20 mpg? That's what I was getting about 10 years ago, then at about the same time the "downstream bank 2 out of tolerance" code popped up (P0240?) I began noticing a decline. Now I fill with 13-14 gallons and get 200 miles if I'm lucky. Doesn't take a math teacher to figure out how crappy that is. I'll be cleaning the MAF and popping new O2s in this weekend, and I'll report my mileage after the first full tank.

3rd cat delete will have to wait.

 

[stephen newberg]

Mine has been consistent on fuel consumption, within a reasonable range, since new. If yours is showing a constant small decline, something is certainly wrong.

pax, smn

 

[98SF19]

Front o2 sensor

I got the MAF cleaned up pretty well, although it wasn't very dirty to begin with (maybe I was just expecting worse). But please tell me how in thee SAM **** does one remove the o2 sensor in front of the forward cat? It sits on top of the pipe at the bottom of the engine compartment at a weird angle, so that you can't see it directly from below, it's too deep and too hard to get to from above, and there's hardly any room to get a wrench in there, much less turn it. The one in front of the rear bank cat was annoying enough, and after letting a small shot of wd40 set in, I was able to hammer the wrench to remove it. But I just couldn't figure out the front one.

So now I have a new rear bank pre-cat sensor, and the one in front of the forward cat is pretty old. How does the PCM work if the signals from each sensor (pre-cats) differ significantly? I did disconnect the battery while I was doing the work, which was over an hour.

So I restarted, gave it about 10 minutes to warm up, and no CEL. Took my sons for a few wide-open runs, still no CEL. I think I'll have the pros do the front sensor, then I'll look forward to filling up the tank to check mileage.

Got a chunk of crud in each eye and my neck muscles are killing me.