Catconverter burn-up..

[TomPrestin]

fixkick pid='12318' dateline='1574168998']CAT 101 : basics (then covering beat to death CAT last)
when you start a cold engine the CAT gets a load of unburned fuel (HC) dead cold, and ECU is in cold start rich burn mode and the cat gets light off fast. (and must stay so)

then ECU goes to hot engine mode, and goes to STOICH,  14.7:1 AFR, and if the cat is too far from the exhaust header it can now go DEAD< a dead cat. (means not lit off)
then it sucks up fuel cold , and overheats at some point , mostly going fast. after the fuel soak up. (dead) (suckup , fry , suckup , fry repeat)

The goal is , A hot engine, and at every stop signal, (stop light /sign) the CAT stays LIT off, or it can overheat later, (imagine this endless cat torture if not working right)

The cure is get the cat close to the header. close as possible. IF You do the CAT can list 100,000 miles, even more. mine had 150k on it.
looking at examples:
see Modern V6 engines with 2 cats mounted at 45degree angle dead close, this is THAT and WHY. faster light off and stays so, is the reason.

one thing great on this Suzuki Drive line , no extra wasted parts, all parts on topic have  PURPOSE,  so here I will exhibit what parts do DOWN UNDER,

this was your car, before the hurricane. (stock car)

I pasted this photo of the SUZ EPC, parts cat, (official dwg)

parts 7 must be there.  if a custom cat , one must design there own mounts. if not? the cat beats it self to death from the  nasty 4cyclinder  huge vibrations.  and the monolith element inside cracks then breaks up to chucks then dust, (my jeep 88' did the same. and I made a custom mount, to replace the jeep mount that broke, every 10,000  miles (fixed and drove 250k more and I had 2 of those cars, one Pickup and one 4door SUV both failed. both cured.)


part 17 is to body frame rail, mount.
part #1 is what I call the funky tube. (some are double walled) if are and not upgraded it insides collapses.   <<<the TSB is here)

if your part 1:   can be missing, or not a 1996+ (Good one)  or 1992-95 bad one, then all this matters,  what matters is the the insides of pipe 1 is not collapsed.
other cards CAT's  are  with a pelleted  cat guts do not fail shook hard, (James Bond, shaken but not stirred)

now some more news.
SOME OBD2 DTC tests are skipped, if some tests before it failed. P0421 is that, if the 02 front fails it can not test the rear 421 test. so skips this.
that means fix 1 thing and 2nd error happens, see why? (called unmasking) OBD2 joys.

NO lie this cat is fragile,  that is a fact, some make huge rattling sound inside (the doomed sound) 
or buy a pellet cat,  for 1.6 to 2.0L and use that, end the pain of weak CATS.

TSB = suzuki technical service bulletins. ( on all cars read these first then turn the wrench)

and last good luck with your custom Kick,  and please put a human protect on that side crash bar mounts. (foam? wrapped?) IDK but a for sure knee killer.

Took pictures under the hood today- will post tomorrow after converting.  Did EGR test, seems good, does as your test suggest when opened, recovers quickly when released (closed).  

Considering how many times I've had this thing in pieces I am certain there is/never was (possibly removed by PO) the #17 body to frame rail mount for CAT, so something to look in to.  

I actually have a boost/vac gauge of the same set as currently installed, but not hooked up yet. I'll try to get that accomplished this weekend also and have constant eyes on actual VAC levels now that you've informed me scanner is not accurate direct vac reading.  (thank you)

Both 02 sensors seem to be doing what they should as I observe during regular driving, will still pull down info and post when I have time.  

forgive my ignorance, but I'm lost on the CAT "LIT" subject.  mostly because I don't know definition of LIT.  Searched site and couldn't find it in the jargon area.  

On the high idle-  Apologies for the location confusion, I'm in Minnesota.  vehicle was originally a Florida car (where I found it) but now resides in MN, so winters are cold.  first cold was 10-20 overnight, a few weeks ago.  Started as expected ran 1600rpm until warm then dropped to 800.  recently warmer (last week and this in the 40's) but idle surging on start up to 2800rpm, holding there until warmup then dropping down to 800.  possible IAC or ISC just need cleaning?  or indicator of vacuum issues waiting to be tested/visualized.  Again- I don't see any places with cracks or damage that could be causing the vac leak, but certainly not going to stop looking.  

On the subject of headers-  as stated I have the Thorley, which you are correct the EGR port is not well designed.  Alternately the gasket they send for mounting is a softer compression gasket which I have to imagine could EASILY press into the machined EGR passage and block it partially or completely simply with installation.  IF I'm following correctly- EGR test good suggests all EGR passageways operating reasonably?  For sake of convo; if the EGR exhaust port were blocked, could it be a contributor to the CAT burnup issue?

More to come when I can make time!   Thank you!!

Pictures finally