Catconverter burn-up..

[fixkick]

Quick response before I have to step into work-  did a lot of reading through the the site yesterday, noticed that standard plenum vacuum at hot idle should be 20 inHg, mine is stable at 8..  so I may have a vac leak somewhere, probably contributing.  I have a new VSV2, and nothing under the hood is "custom" I've gone to great lengths to make all the mechanical components as original as possible.  Header was cracked bad, currently running a doug thorley, no funky tube, goes directly to Cat inlet.  Cat hangs from rubber grommets so I'm sure it is bouncing around a bit, also maybe contributing.  my scanner will log/save so I'll pull down the info and post.  thank you!!  I'll update again asap

19 OR 20" IS HOT IDLE,  800RPM AND NOTHING ELSE , not cold ,  not 8. SO RPM IS important here.
the engine cam must timed correctly and compression near 180 PSI, all 4,
then no melted cats, if melted the engine can not pump air, and can not have normal  vacuum.
the header can not be cracked or it sucks in air, and makes the 02 front go NUTS.
the Exhaust pressure pulse,  goes Positive then goes to slight vacuum  each PUTT . (AND CRACKS ARE NO GOOD HERE, NO CAR WITH EFI GOOD with cracks near O2)
was cracked, or is?.  so the Thorney has no EGR #4 port?  You say?, if yes, no port EGR will never work, ever. ((ahh funky means 90deg suzuki front tube, sure)

you  should do photos of what you  have so wild questions end ,  old cars, have wrong parts and bad parts and missing parts, endless , but yours is not. got it.


8" inches HG vacuum is NO GOOD ever,  (unless EGR sticks open or what told above)
vacuum wrong is big time serious.

on an normal engine, we see about 19" hot 800 idle
then blip the throttle and vacuum drops fast and recovers fast when released.
with a melted cat if car runs at all, some do not ( the vacuum acts very odd and very slow to recover,  unlike any good engine behaves.

is the cat sized for 1.6L or 3L/?  sizes matters, to get it lit off and keeping that  way, only correct sized cats work. 

ECT read 300 ohms hot engine, if not burn up cat you will, (ECU sees below 150f water temp for actual hot engine goes rich and is very bad. 180F is correct or more, 195f are sold.
some folks in EU have like 3 types of ECT and buy the wrong own, and pure hell ensues.

when p0400 pops we scan and get the freeze frame so we can see if EGR A or B test failed. one is cruise and other us cut fuel test. ( we see this with vacuum readings in the freeze frame)
but with 8HG vacuum the tests have no change for sure the cut fuel mode, EGR B test. hopeless....

cam timed right. (not using the 16v cam cog wheel false marks !!!)
spark timed right
compression at spec, 180psi at sea level, my compression page covers correction rules for folks at height altitude.
the vacuum at 19" HG hot. engine 800 rpm.

those are the basics on the engine, if not right, EFI can and will go nuts, the EFI adjusts for normal engine wear and 8" Vacuum is not normal at all, not even 1/2.