Gutting your pre cats
07-21-2011, 07:08 PM
#41
That's what nmexMAX, too, did with his header set-up. I was thinking of leaving the sensors in the exhaust, so it wouldn't be so obvious when doing a visual inspection. Although in NY, I'm pretty sure the visual inspection is simply to confirm existence of the main cat.
Manny sold me an old, unused SIM from years ago. It's pretty backyard-electronics, but if it works it works. 036mtmax, where'd you get your sim?
Manny sold me an old, unused SIM from years ago. It's pretty backyard-electronics, but if it works it works. 036mtmax, where'd you get your sim?
I havn't got one yet because i heard 02sim went out of business so im waiting to hear someone chime in if they know where i can get a descent one..
07-21-2011, 07:11 PM
#42
oh Eirik,lol
07-21-2011, 08:18 PM
#43
Just a question since I'm considering gutting my cats. Why not just use spark plug non foulers? Much easier to get and cheaper.
Any reason why you aren't considering or mentioning them?
Any reason why you aren't considering or mentioning them?
07-21-2011, 09:41 PM
#45
Senior Member
Join Date: Dec 2005
Location: Leicester, Ma
Posts: 1,124
i havent posted on the site for a few months but i did this mod last year before winter. TO get rid of the SES light all you need it 4 spark plug antifoulers. 2 short and 2 long. Drill out the 2 long ones so thr o2 sensor will fit. Put it all together and it the 2 sec o2s will read less than the primaries therefore no light. I get a light once in a while say if i dont drive the car for a week but i just do the ecu relearn and good to go. Nice to know is all i need is a better exhaust than stock and i may be at the 240 mark. Have all those mods as well minus the larger exhaust but have the SSIM.
07-21-2011, 09:43 PM
#46
Senior Member
Join Date: Dec 2008
Location: NYC
Posts: 1,782
07-21-2011, 09:50 PM
#47
i havent posted on the site for a few months but i did this mod last year before winter. TO get rid of the SES light all you need it 4 spark plug antifoulers. 2 short and 2 long. Drill out the 2 long ones so thr o2 sensor will fit. Put it all together and it the 2 sec o2s will read less than the primaries therefore no light. I get a light once in a while say if i dont drive the car for a week but i just do the ecu relearn and good to go. Nice to know is all i need is a better exhaust than stock and i may be at the 240 mark. Have all those mods as well minus the larger exhaust but have the SSIM.
nice jeff thanks for the info ill give it a shot first..
07-27-2011, 06:22 AM
#48
Mechanic has the car today. Gutting both pre-cats and installing the O2 sim. Sitting here at the office, hoping for good news before the day is out.
Good news would mean:
1. The low-end mystery rattle will be gone.
2. The O2 Sim install was done accurately, with no CEL.
3. The original-equipment main cat is still A-OK.
4. (optional) Improved power with the exhaust efficiency.
Good news would mean:
1. The low-end mystery rattle will be gone.
2. The O2 Sim install was done accurately, with no CEL.
3. The original-equipment main cat is still A-OK.
4. (optional) Improved power with the exhaust efficiency.
07-27-2011, 07:09 AM
#49
Mechanic has the car today. Gutting both pre-cats and installing the O2 sim. Sitting here at the office, hoping for good news before the day is out.
Good news would mean:
1. The low-end mystery rattle will be gone.
2. The O2 Sim install was done accurately, with no CEL.
3. The original-equipment main cat is still A-OK.
4. (optional) Improved power with the exhaust efficiency.
Good news would mean:
1. The low-end mystery rattle will be gone.
2. The O2 Sim install was done accurately, with no CEL.
3. The original-equipment main cat is still A-OK.
4. (optional) Improved power with the exhaust efficiency.
!
07-27-2011, 08:12 AM
#50
Senior Member
Join Date: Dec 2008
Location: NYC
Posts: 1,782
Mechanic has the car today. Gutting both pre-cats and installing the O2 sim. Sitting here at the office, hoping for good news before the day is out.
Good news would mean:
1. The low-end mystery rattle will be gone.
2. The O2 Sim install was done accurately, with no CEL.
3. The original-equipment main cat is still A-OK.
4. (optional) Improved power with the exhaust efficiency.
Good news would mean:
1. The low-end mystery rattle will be gone.
2. The O2 Sim install was done accurately, with no CEL.
3. The original-equipment main cat is still A-OK.
4. (optional) Improved power with the exhaust efficiency.
Nice!
07-27-2011, 09:08 AM
#51
I'd definitely use the O2 extensions/whatever you want to call them, before buying a sim. They're a widely-known "secret" that hasn't penetrated into this particular forum for some reason. The 4th gen guys are all about 'em--my '97 owning friend was able to defeat the big-cat-not-working-right CEL, even.
I wanted to use the horse thing, but didn't like the repost sign he was holding, so I refrained.
@the guy who said "BUT EIRIK FRONT PRECAT SOMETHING SOMETHING": It's not KRRZ's theory, he just defends it because he tore down that one engine that one time and saw some of the rings were bad, but not all of them, and concluded that that can only be from the disintegrating pre-cat theory, and not that just some of the rings were bad/installed wrong when the car was assembled.
"Always" is a strong word. My '05 6MT has shown no signs of burning oil in the 2500 miles I've put on it (95->97.5K miles). Though I didn't own it then, I estimate that my '02 was burning about 1 qt/2500 miles around then, worsening to 1qt/800 miles after 120K miles before levelling out to 1qt/~1400 miles when I destroyed it at 133K miles.
I wanted to use the horse thing, but didn't like the repost sign he was holding, so I refrained.
@the guy who said "BUT EIRIK FRONT PRECAT SOMETHING SOMETHING": It's not KRRZ's theory, he just defends it because he tore down that one engine that one time and saw some of the rings were bad, but not all of them, and concluded that that can only be from the disintegrating pre-cat theory, and not that just some of the rings were bad/installed wrong when the car was assembled.
"Always" is a strong word. My '05 6MT has shown no signs of burning oil in the 2500 miles I've put on it (95->97.5K miles). Though I didn't own it then, I estimate that my '02 was burning about 1 qt/2500 miles around then, worsening to 1qt/800 miles after 120K miles before levelling out to 1qt/~1400 miles when I destroyed it at 133K miles.
07-27-2011, 09:39 AM
#52
Mechanic has the car today. Gutting both pre-cats and installing the O2 sim. Sitting here at the office, hoping for good news before the day is out.
Good news would mean:
1. The low-end mystery rattle will be gone.
2. The O2 Sim install was done accurately, with no CEL.
3. The original-equipment main cat is still A-OK.
4. (optional) Improved power with the exhaust efficiency.
Good news would mean:
1. The low-end mystery rattle will be gone.
2. The O2 Sim install was done accurately, with no CEL.
3. The original-equipment main cat is still A-OK.
4. (optional) Improved power with the exhaust efficiency.
07-27-2011, 10:10 AM
#53
Still waiting. Apprehensive to hear, "Snapped these bolts", "Main cat is toast", or the worse... "The mystery rattle is still there."
But then, I don't want to jinx this thing.
07-27-2011, 11:34 AM
#55
No. If it were, then it would have been obvious applying the listening tool to the timing chain cover.
Just got off the phone with my mechanic... the rear pre-cat was successfully gutted while on the car, (and on the lift). It took about an hour. The front pre-cat is next, and that obviously needs to be removed.
Like (most) everyone here was saying: the rear is easy to access, but a PITA to gut. Whereas the front is a PITA to access, but easy to gut.
More later.
Just got off the phone with my mechanic... the rear pre-cat was successfully gutted while on the car, (and on the lift). It took about an hour. The front pre-cat is next, and that obviously needs to be removed.
Like (most) everyone here was saying: the rear is easy to access, but a PITA to gut. Whereas the front is a PITA to access, but easy to gut.
More later.
Last edited by Rochester; 07-27-2011 at 12:30 PM.
07-27-2011, 12:13 PM
#56
Senior Member
Join Date: Dec 2008
Location: NYC
Posts: 1,782
No. If it were, then it would have been obvious applying the listening tool to the timing chain cover.
Just got off the phone with my mechanic... the rear pre-cat was successfully gutted while on the car, (and on the lift). It took about an hour. The front pre-cat is next, and that obviously needs to be removed.
Like everyone here was saying: the rear is easy to access, but a PITA to gut. Whereas the front is a PITA to access, but easy to gut.
More later.
Just got off the phone with my mechanic... the rear pre-cat was successfully gutted while on the car, (and on the lift). It took about an hour. The front pre-cat is next, and that obviously needs to be removed.
Like everyone here was saying: the rear is easy to access, but a PITA to gut. Whereas the front is a PITA to access, but easy to gut.
More later.
07-27-2011, 12:56 PM
#58
The front pre-cat gutted effortlessly, although he had to laser-torch a few inches off the manifold heat-shield in order to access the bolts without dropping the heat shield... which he preferred over the alternative, which was potentially trashing the entire heat-shield.
He said there was a metal ring within the front pre-cat which looked like it should be pressed into the pre-cat housing, and yet just fell out as things were unbolted. The suspicion is that my low-end rattle was this loose ring thing... because the visual inspection of all the cats led him to think they were all fine.
While it kind of sucks that this noise could have been addressed by simply removing the ring
, I'm going to end up with gutted pre-cats at the end of the day. And according to a number of people here, that's a thumbs-up situation.
Either way, I'm not picking the car up until tomorrow.
Hi, Froggy!
He said there was a metal ring within the front pre-cat which looked like it should be pressed into the pre-cat housing, and yet just fell out as things were unbolted. The suspicion is that my low-end rattle was this loose ring thing... because the visual inspection of all the cats led him to think they were all fine.
While it kind of sucks that this noise could have been addressed by simply removing the ring
, I'm going to end up with gutted pre-cats at the end of the day. And according to a number of people here, that's a thumbs-up situation.Either way, I'm not picking the car up until tomorrow.
Hi, Froggy!
Last edited by Rochester; 07-27-2011 at 12:59 PM.
07-27-2011, 12:59 PM
#59
The metal ring is not pressed in. I seriously doubt that was your noise. Let's cross our fingers and hope it was something in the rear cat that he couldn't see. I'm still betting on the heat shield a tiny bit loose due to corrosion at the fastener.
07-27-2011, 01:00 PM
#60
07-27-2011, 01:04 PM
#61
07-27-2011, 01:32 PM
#62
Senior Member
Join Date: Dec 2008
Location: NYC
Posts: 1,782
The front pre-cat gutted effortlessly, although he had to laser-torch a few inches off the manifold heat-shield in order to access the bolts without dropping the heat shield... which he preferred over the alternative, which was potentially trashing the entire heat-shield.
He said there was a metal ring within the front pre-cat which looked like it should be pressed into the pre-cat housing, and yet just fell out as things were unbolted. The suspicion is that my low-end rattle was this loose ring thing... because the visual inspection of all the cats led him to think they were all fine.
While it kind of sucks that this noise could have been addressed by simply removing the ring, I'm going to end up with gutted pre-cats at the end of the day. And according to a number of people here, that's a thumbs-up situation.
Either way, I'm not picking the car up until tomorrow.
Hi, Froggy!
He said there was a metal ring within the front pre-cat which looked like it should be pressed into the pre-cat housing, and yet just fell out as things were unbolted. The suspicion is that my low-end rattle was this loose ring thing... because the visual inspection of all the cats led him to think they were all fine.
While it kind of sucks that this noise could have been addressed by simply removing the ring
, I'm going to end up with gutted pre-cats at the end of the day. And according to a number of people here, that's a thumbs-up situation.Either way, I'm not picking the car up until tomorrow.
Hi, Froggy!
07-27-2011, 01:47 PM
#63
Do you know what it's there for? I'm not at the shop, so I'm kind of fuzzy about what he's describing over the phone.
Haven't been billed yet. Besides, we never talk about cost, and he's never charged me anything I wasn't prepared for. Been going to him for years. He's a rare thing... an honest mechanic.
Haven't been billed yet. Besides, we never talk about cost, and he's never charged me anything I wasn't prepared for. Been going to him for years. He's a rare thing... an honest mechanic.
Last edited by Rochester; 07-27-2011 at 02:41 PM.
07-27-2011, 02:55 PM
#64
I believe it's to contain the catalytic material within the cat. It appears the body of the precat has a cylindrical hollow space in which the preformed material is dropped in. The ring is then placed on the shelf at the top. In other words, it's designed to facilitate the ease of manufacturing.
07-27-2011, 04:06 PM
#65
Oh well I can't get the page up, but if your talking about the forward Pre cat I see no o ring on the schematics. Page 10 of the EM section of the Service Manuel. The is a metal ring that goes after the pre cat but nothing where it connects to the manifold. I forgot where you said the ring was at.
07-27-2011, 04:16 PM
#66
Oh well I can't get the page up, but if your talking about the forward Pre cat I see no o ring on the schematics. Page 10 of the EM section of the Service Manuel. The is a metal ring that goes after the pre cat but nothing where it connects to the manifold. I forgot where you said the ring was at.
Last edited by nelledge; 07-27-2011 at 04:20 PM.
07-27-2011, 06:41 PM
#71
The precats do the preliminary conversion of exhaust gases immediately (albeit with a smaller conversion efficiency) since the main cat must reach operating temperature to work at optimum efficiency. Taking out the precats yields 'dirtier' exhaust gases for the first few minutes of engine operation.
07-27-2011, 07:05 PM
#72
To clarify, I don't think 'rattle' is the correct word John, not from what I heard. It's a whistle or whine type noise, like an IPS bearing might make.
I still suspect that there was one area of the cat that had created a 'flute' which caused a whistle noise to resonate through the exhaust, but only at a certain resonace (RPM/Load)
Can't wait to hear the results
I still suspect that there was one area of the cat that had created a 'flute' which caused a whistle noise to resonate through the exhaust, but only at a certain resonace (RPM/Load)
Can't wait to hear the results
07-27-2011, 08:25 PM
#73
To clarify, I don't think 'rattle' is the correct word John, not from what I heard. It's a whistle or whine type noise, like an IPS bearing might make.
I still suspect that there was one area of the cat that had created a 'flute' which caused a whistle noise to resonate through the exhaust, but only at a certain resonace (RPM/Load)
Can't wait to hear the results
I still suspect that there was one area of the cat that had created a 'flute' which caused a whistle noise to resonate through the exhaust, but only at a certain resonace (RPM/Load)
Can't wait to hear the results
Nope mine was a distinct heat shield sounding rattle and when we took the cat down the bulk of the mesh inside the cat was shifting around inside the cat which was causing the noise.
07-28-2011, 04:30 AM
#74
To clarify, I don't think 'rattle' is the correct word John, not from what I heard. It's a whistle or whine type noise, like an IPS bearing might make.
I still suspect that there was one area of the cat that had created a 'flute' which caused a whistle noise to resonate through the exhaust, but only at a certain resonace (RPM/Load)
Can't wait to hear the results
I still suspect that there was one area of the cat that had created a 'flute' which caused a whistle noise to resonate through the exhaust, but only at a certain resonace (RPM/Load)
Can't wait to hear the results
For those who are reading this... TunerMaxima3000 tried to analyze this noise last week, so he's exactly familiar with what I've been experiencing.
07-28-2011, 04:58 AM
#76
When we spoke towards the end of the day yesterday, he had just bolted everything back together, and was about to start on the O2 Sim. I told him not to sweat it, and leave it for the next day. No sense in forcing a deadline when I'm in no rush to get the car back. We're a 2-car household, and I mostly work from home.
I have to admit, all this talk about power gains has me a little psyched. Naturally, headers are the optimal approach, but maybe gutted pre-cats mated to a Cattman y-pipe will be a pretty close second.
I have to admit, all this talk about power gains has me a little psyched. Naturally, headers are the optimal approach, but maybe gutted pre-cats mated to a Cattman y-pipe will be a pretty close second.
07-28-2011, 05:23 AM
#77
Cool. I was looking at getting a Y Pipe and mating it to gutted pre cats myself. Hopefully you do get some gains. Maybe you could compare with somebody running OBX headers? OP, How is your car running?
07-28-2011, 06:54 AM
#78
Not going to happen. I don't care about dyno numbers, and there aren't any other 5.5 gen Org members in my area. However, if there were another modded 5.5 gen around here, I would love to compare this and a number of other things. Thank God for the Org... sometimes I feel like I live on an island.
