Questions that I think should be asked are; how can I confirm this vehicle came with 2 or 4 cats originally?
Maybe I'm misunderstanding something, didn't you say this car was the group .3185 that came with 4 cats?
EDIT: I think I see what you're gett ing at. You want to verfy it. I went to Walkera's exhaust catalog and it shows 2 cats in the diagrams and only lists .3185 family but in the converter catalog it specifies a right rear and left rear but no fronts. Alldata also shows only 2 cats, but like you said, ARB site indicates 4, so WTF? Big help I am! Does the motor or mitchell guide say anything?
EDIT AGAIN: The EO doesn't change the cat configuration or number of cats required if that's what you were asking.
EVAPONLY, Do you know what the front cats look like on a 4.8 or 5.3L LS motor? If not and you haven't ever seen them you aren't looking close enough. On the ALLDATA picture you posted the other day I circled them. On the 6.0L they are somewhat more obvious but still just a slight swell in the pipe, not a normal looking cat. Same with the Jeep 4.0L that has two cats. The front one is just a swell in the pipe where it crosses the oil pan.
People are usually shocked when they find out I'm not a very good electrician.
Yes some of these 2001/2002 Chevy and GMC 5.3L had 4 cats and some had 2 cats.
I haven't seen any on the 2001 models , but seen many on the 2002s.
Not the same as the 6.0L that can share the Big Block 8.1L exhaust.
On the 5.3L with the 4 cat exhaust, the Front Cats are bolted right up to the exhaust manifold and part of the Header Pipe. The Front Cats are small Pre Cats about 5 or 6 inches long. One on each side.
They look like the Header Pipe is just a bit Fatter for that 5 or 6 inches.
Have never seen aftermarket replacements for the Front Cats.
Have never seen em on a 4.8L.
If those small front cats blew out and went downstream, don't think most techs would catch it unless the Rear Cats failed Restricted as a result.
But isn't that from a 2004 savanna 4.8? Not challenging you or second guessing, I'm just trying to get my head around this whole 4 cat 2001 suburban thing. I haven't found anything on it beside ARB "4" designation.
In that diagram, I never would have identified those as CATs without your help!
Thank you so much for posting! Again, I never would've ID'd those as CATs without your help, especially considering the lack of clear and collaborative reference. Still, I would have done as OP and pass it (after sweating the conflicting info, like I often do).
Funny how the usually-welcomed presence of a VECI complicated things!
Shoutout None for posting an actual pic to show us. Personally I learn better with visuals. Here’s an example of one that requires 4 cats on a 01 suburban 5.3, engine family 1GMXA05.3185. Pretty easy to miss if you don’t know they’re suppose to be there. Especially since Motor book will say 2 and Alldata does not clarify. You can see the small pre-cat following into the main catalyst.
Does anyone here have a scan of the 4 oxygen sensors at idle and 2000 rpm? What's interesting is that B1S1 and B2S2 are positioned after the warm up cats. I'd be curious to see what scandata looks like.
Why make it simple, when it will work equally as well complicated.