Catconverter burn-up..

[TomPrestin]

Hey All-

1996 X90, 16v G16b.  No Engine mods

I've had my x90 back running since early this spring and have burnt up 2 Catconverters now.  I've done all the EGR tests with success, no limp mode, but consistent P0400.  I'm leaning towards bad oxygen sensors but I wanted to check in here and get alternate insights before dumping $$$ into both sensors and another new Cat.  

Scanner says I'm getting OxySensor output voltage, but shows "FAIL" on these scanner tests:
Sensor time; [rich-lean] & [lean-rich] - Fail
Minimum sensor voltage - Fail
Maximum sensor voltage - Fail
Time transitions - Fail

Yes, shows failures so its seems like a no-brainer, but I don't know where the scanner is retrieving the tolerances for those tests and therefor don't know how reliable those results are, so it seems intuitive to inquire here also.

Here's what the scanner is showing generally at warm idle [783rpm average]

Fuel System1: CL
Calculated Load: 17.6%
Coolant Temp: 172f
Short Term Fuel Trim - Bank1: -0.8%
Long Term Fuel Trim - Bank1: 3.9%
Intake Manifold Absolute Pressure: 8.1 inHg
Ignition Timing Advance: 9.0 degrees
AirFlowRate from MAF: 0.3 lb/min
Oxy Sensor Output Voltage B1-S1: 0.740V
Oxy Sensor Output Voltage B1-S2: 0.545V
Short Term Fuel Trim - B1-S1: -0.8%
Short Term Fuel Trim - B1-S2: 99.2%


Any thoughts or insight on the subject would be very much appreciated!

[fixkick]

Hey All-

1996 X90, 16v G16b.  No Engine mods

I've had my x90 back running since early this spring and have burnt up 2 Catconverters now.  I've done all the EGR tests with success, no limp mode, but consistent P0400.  I'm leaning towards bad oxygen sensors but I wanted to check in here and get alternate insights before dumping $$$ into both sensors and another new Cat.  

Scanner says I'm getting OxySensor output voltage, but shows "FAIL" on these scanner tests:
Sensor time; [rich-lean] & [lean-rich] - Fail
Minimum sensor voltage - Fail
Maximum sensor voltage - Fail
Time transitions - Fail

Yes, shows failures so its seems like a no-brainer, but I don't know where the scanner is retrieving the tolerances for those tests and therefor don't know how reliable those results are, so it seems intuitive to inquire here also.

Here's what the scanner is showing generally at warm idle [783rpm average]

Fuel System1: CL
Calculated Load: 17.6%
Coolant Temp: 172f
Short Term Fuel Trim - Bank1: -0.8%
Long Term Fuel Trim - Bank1: 3.9%
Intake Manifold Absolute Pressure: 8.1 inHg
Ignition Timing Advance: 9.0 degrees
AirFlowRate from MAF: 0.3 lb/min
Oxy Sensor Output Voltage B1-S1: 0.740V
Oxy Sensor Output Voltage B1-S2: 0.545V
Short Term Fuel Trim - B1-S1: -0.8%
Short Term Fuel Trim - B1-S2: 99.2%


Any thoughts or insight on the subject would be very much appreciated!

the front sensor must work,  S1
and if not that causes limphome, and rich AFR,
the sensors has 2 parts, heater and the O2 cell.   both must work.(inside)
if you had  scan tool that would graph the o2 sensor out output, it must swing like , hunting for perfect air fuel rato (AFR)
like this.

blue trace bottom


and this hand held tool




more here.

https://fixkick.com/ECU/Authority/A_Full_OBD2_scan.html

[fixkick]

lets start over, who said the burned up 2 Catconverters now. by what measure, P0421 codes, or smog man or?

The P0400 means the EGR fails.....  in some way , if the cat GUTS broke up in pieces and went byebye EGR then fails too.  the cat must be there and must have normal back pressure or the EGR Modulator FAILs to work. (goes offline) and P0400 is the results. but is the effect not the cause, in this case. (or there are 2 problems, unrelated, and common on old cars)

did you fail a smog test or something, please advice  here.
thanks for posting !

[TomPrestin]

I have a graphing tool- S1 swings from .055 -.755, S2 swings from .035 - 0.075. Visualization suggests both sensors working correctly, which is why I'm confused about the test "fails" and why it seems to be having excessively high exhaust temp (Assumed thus the cat burn-up)

[TomPrestin]

lets start over, who said the burned up 2 Catconverters now. by what measure, P0421 codes, or smog man or?

The P0400 means the EGR fails.....  in some way , if the cat broke up in pieces and went byebye EGR then fails too.  the cat must be there and must have normal back pressure or the EGR MODulatopr FAILs to work. (goes offline)

did you fail a smog test or something, please advice  here.
thanks for posting !

first one was obvious.  header turned dark from over-heat, lost all power slowly and dramatically, pulled the cat and it was melted to a rock.  I'm getting same subtle indicators now again. mostly progressive vibration from the cat as it sounds audibly to be deteriorating.  I'm in Minnesota so no smog test. 

no P0421, only P0400 that is incessant.  I clear the code, drive for a bit comes back, but no clear circumstance.   Sometimes first drive, sometimes second.  sometimes on first start up, sometimes at random while driving.  

New EGR, tested ISC good.  decent gas milage so not in limp, ego exhaust port should be open as the engine/header only has about 8000 miles on it after total rebuild.

only other bit of information I left out of original post is recently it has started to hiccup a bit.  at cold idle worst, or low throttle, not with open throttle.  not a full misfire, seemed almost like it had bad gasoline, but I'm on tank 3 from different locations and same issue.

fuel pressure is stable and good.

[fixkick]

lets start over, who said the burned up 2 Catconverters now. by what measure, P0421 codes, or smog man or?

The P0400 means the EGR fails.....  in some way , if the cat broke up in pieces and went byebye EGR then fails too.  the cat must be there and must have normal back pressure or the EGR MODulatopr FAILs to work. (goes offline)

did you fail a smog test or something, please advice  here.
thanks for posting !

first one was obvious.  header turned dark from over-heat, lost all power slowly and dramatically, pulled the cat and it was melted to a rock.  I'm getting same subtle indicators now again. mostly progressive vibration from the cat as it sounds audibly to be deteriorating.  I'm in Minnesota so no smog test. 

no P0421, only P0400 that is incessant.  I clear the code, drive for a bit comes back, but no clear circumstance.   Sometimes first drive, sometimes second.  sometimes on first start up, sometimes at random while driving.  

New EGR, tested ISC good.  decent gas milage so not in limp, ego exhaust port should be open as the engine/header only has about 8000 miles on it after total rebuild.

only other bit of information I left out of original post is recently it has started to hiccup a bit.  at cold idle worst, or low throttle, not with open throttle.  not a full misfire, seemed almost like it had bad gasoline, but I'm on tank 3 from different locations and same issue.

fuel pressure is stable and good.

the first cat did burn up,  from engine super rich, that is what cause burn up , the CEL lamp also flashes when the ECU knows it is rich, the flash means ( go  slow or cat burns up)
the 2nd cat IDK,  why , same reasons? who knows.
but lets talk 2 things here, first off there are 2 causes of rich, (gross rich and simple rules)
it is in limphome ,  for many reasons, even 02 front dead,
or the ECU is lost.
lets do lost,  (02 dead,front means injection rates are now lost,  no real controls only the MAF output, and is purposefully rich, so you dont burn up exhaust valves from too lean.

Injectors can leak, or fuel pressure way too high, FPR bad and causes this, or 02 sensors is bad or reads wrong (exh. leaks near it)

the only way to prove closed loop is to see the scan tool show CL, for closed loop ,noT OL open loop cruising. (and at idle hot)
or scan the 02 and plot it. it must swing and swing on a 0.45v center. 
the can be no exhaust leaks near the front 02 or it goes rich, AFR super rich, max.

if the new cat broke up EGR is not the worry, the CAT must be good to get EGR working, EGR uses that CAT to gauge full engine load, and run EGR flows based off of that.
if the CAT melts, (engine goes weak cant pump air) then EGR overflows wrong, due to huge CAT back pressure and causes even more power loss...
maybe the second cat got hit by road debris.  or vibrated too hard and broke up, had a jeep do that 3 times,  (made a mount for the cat to keep it from vibrating and was cure.

is there not a frame mount for the cat? on this car, IRRC.  I forget, but will  look that up in the AM.

Seen one china clone maf used that run way too high and the eCu could not trim it down so high and ran rich, full time. o2 could not correct this error.

mGP on my 96 5sp was 28mpg, that is possible. tad less in town.

if the O2 hunts at light cruise say 40 MPH, the ECU and 02 are ok,  it must hunt around 0.45volts just like the scope views show.  no stuck high ,low or offset.
this and short turn true at same time also tells me what is up,

do the EGR stall test, and live test yet? 1996, up, the live test is rear wheels off the ground and 1mph or faster, no 0mph,
per my gen2, EGR page. and FSM rules on same.
my guess is the stall test passes, (exh paths all good)  and is vacuum issue, CAT blown out is top of list. for EGR death.

[TomPrestin]

lets start over, who said the burned up 2 Catconverters now. by what measure, P0421 codes, or smog man or?

The P0400 means the EGR fails.....  in some way , if the cat broke up in pieces and went byebye EGR then fails too.  the cat must be there and must have normal back pressure or the EGR MODulatopr FAILs to work. (goes offline)

did you fail a smog test or something, please advice  here.
thanks for posting !

first one was obvious.  header turned dark from over-heat, lost all power slowly and dramatically, pulled the cat and it was melted to a rock.  I'm getting same subtle indicators now again. mostly progressive vibration from the cat as it sounds audibly to be deteriorating.  I'm in Minnesota so no smog test. 

no P0421, only P0400 that is incessant.  I clear the code, drive for a bit comes back, but no clear circumstance.   Sometimes first drive, sometimes second.  sometimes on first start up, sometimes at random while driving.  

New EGR, tested ISC good.  decent gas milage so not in limp, ego exhaust port should be open as the engine/header only has about 8000 miles on it after total rebuild.

only other bit of information I left out of original post is recently it has started to hiccup a bit.  at cold idle worst, or low throttle, not with open throttle.  not a full misfire, seemed almost like it had bad gasoline, but I'm on tank 3 from different locations and same issue.

fuel pressure is stable and good.

the first cat did burn up,  from engine super rich, that is what cause burn up , the CEL lamp also flashes when the ECU knows it is rich, the flash means ( go  slow or cat burns up)
the 2nd cat IDK,  why , same reasons? who knows.
but lets talk 2 things here, first off there are 2 causes of rich, (gross rich and simple rules)
it is in limphome ,  for many reasons, even 02 front dead,
or the ECU is lost.
lets do lost,  (02 dead,front means injection rates are now lost,  no real controls only the MAF output, and is purposefully rich, so you dont burn up exhaust valves from too lean.

Injectors can leak, or fuel pressure way too high, FPR bad and causes this, or 02 sensors is bad or reads wrong (exh. leaks near it)

the only way to prove closed loop is to see the scan tool show CL, for closed loop ,noT OL open loop cruising. (and at idle hot)
or scan the 02 and plot it. it must swing and swing on a 0.45v center. 
the can be no exhaust leaks near the front 02 or it goes rich, AFR super rich, max.

if the new cat broke up EGR is not the worry, the CAT must be good to get EGR working, EGR uses that CAT to gauge full engine load, and run EGR flows based off of that.
if the CAT melts, (engine goes weak cant pump air) then EGR overflows wrong, due to huge CAT back pressure and causes even more power loss...
maybe the second cat got hit by road debris.  or vibrated too hard and broke up, had a jeep do that 3 times,  (made a mount for the cat to keep it from vibrating and was cure.

is there not a frame mount for the cat? on this car, IRRC.  I forget, but will  look that up in the AM.

Seen one china clone maf used that run way too high and the eCu could not trim it down so high and ran rich, full time. o2 could not correct this error.

mGP on my 96 5sp was 28mpg, that is possible. tad less in town.

if the O2 hunts at light cruise say 40 MPH, the ECU and 02 are ok,  it must hunt around 0.45volts just like the scope views show.  no stuck high ,low or offset.
this and short turn true at same time also tells me what is up,

do the EGR stall test, and live test yet? 1996, up, the live test is rear wheels off the ground and 1mph or faster, no 0mph,
per my gen2, EGR page. and FSM rules on same.
my guess is the stall test passes, (exh paths all good)  and is vacuum issue, CAT blown out is top of list. for EGR death.

I'm mostly city driving, getting around 26mpg which is why all the CAT results are a little odd.  I can't do the live test because I have GPS vss., also I don't have all of the "idiot" lights (original gauge indicator lights worked out yet) so CEL is always on.. maybe because of this, maybe because of all kinds of craziness.  Long story short all of the dash is missing, including gauge cluster.  (flooded in Florida hurricane and then abandoned outside for 11 years, everything destroyed)  info Im getting is from scanner and aftermarket gauges (high quality).  I'll attach picture so you can see the extent of this project.  

       

[fixkick]

lets start over, who said the burned up 2 Catconverters now. by what measure, P0421 codes, or smog man or?

The P0400 means the EGR fails.....  in some way , if the cat broke up in pieces and went byebye EGR then fails too.  the cat must be there and must have normal back pressure or the EGR MODulatopr FAILs to work. (goes offline)

did you fail a smog test or something, please advice  here.
thanks for posting !

first one was obvious.  header turned dark from over-heat, lost all power slowly and dramatically, pulled the cat and it was melted to a rock.  I'm getting same subtle indicators now again. mostly progressive vibration from the cat as it sounds audibly to be deteriorating.  I'm in Minnesota so no smog test. 

no P0421, only P0400 that is incessant.  I clear the code, drive for a bit comes back, but no clear circumstance.   Sometimes first drive, sometimes second.  sometimes on first start up, sometimes at random while driving.  

New EGR, tested ISC good.  decent gas milage so not in limp, ego exhaust port should be open as the engine/header only has about 8000 miles on it after total rebuild.

only other bit of information I left out of original post is recently it has started to hiccup a bit.  at cold idle worst, or low throttle, not with open throttle.  not a full misfire, seemed almost like it had bad gasoline, but I'm on tank 3 from different locations and same issue.

fuel pressure is stable and good.

the first cat did burn up,  from engine super rich, that is what cause burn up , the CEL lamp also flashes when the ECU knows it is rich, the flash means ( go  slow or cat burns up)
the 2nd cat IDK,  why , same reasons? who knows.
but lets talk 2 things here, first off there are 2 causes of rich, (gross rich and simple rules)
it is in limphome ,  for many reasons, even 02 front dead,
or the ECU is lost.
lets do lost,  (02 dead,front means injection rates are now lost,  no real controls only the MAF output, and is purposefully rich, so you dont burn up exhaust valves from too lean.

Injectors can leak, or fuel pressure way too high, FPR bad and causes this, or 02 sensors is bad or reads wrong (exh. leaks near it)

the only way to prove closed loop is to see the scan tool show CL, for closed loop ,noT OL open loop cruising. (and at idle hot)
or scan the 02 and plot it. it must swing and swing on a 0.45v center. 
the can be no exhaust leaks near the front 02 or it goes rich, AFR super rich, max.

if the new cat broke up  EGR is not the worry, the CAT must be good to get EGR working, EGR uses that CAT to gauge full engine load, and run EGR flows based off of that.
The cat is part of EGR, (backpressure)
if the CAT melts, (engine goes weak cant pump air) then EGR overflows wrong, due to huge CAT back pressure and causes even more power loss...
maybe the second cat got hit by road debris.  or vibrated too hard and broke up, had a jeep do that 3 times,  (made a mount for the cat to keep it from vibrating and was cure.

is there not a frame mount for the cat? on this car, IRRC.  I forget, but will  look that up in the AM.

Seen one china clone maf used that run way too high and the eCu could not trim it down so high and ran rich, full time. o2 could not correct this error.

mGP on my 96 5sp was 28mpg, that is possible. tad less in town.

if the O2 hunts at light cruise say 40 MPH, the ECU and 02 are ok,  it must hunt around 0.45volts just like the scope views show.  no stuck high ,low or offset.
this and short turn true at same time also tells me what is up,

do the EGR stall test, and live test yet? 1996, up, the live test is rear wheels off the ground and 1mph or faster, no 0mph,
per my gen2, EGR page. and FSM rules on same.
my guess is the stall test passes, (exh paths all good)  and is vacuum issue, CAT blown out is top of list. for EGR death.

I'm mostly city driving, getting around 26mpg which is why all the CAT results are a little odd.  I can't do the live test because I have GPS vss., also I don't have all of the "idiot" lights (original gauge indicator lights worked out yet) so CEL is always on.. maybe because of this, maybe because of all kinds of craziness.  Long story short all of the dash is missing, including gauge cluster.  (flooded in Florida hurricane and then abandoned outside for 11 years, everything destroyed)  info Im getting is from scanner and aftermarket gauges (high quality).  I'll attach picture so you can see the extent of this project.  

you are just like me at 15.5years old building cars from the dead . (best way to learn is this, no better hands on why) cheers to you brother !

seems with that custom car, not having  real scan  tool,, is the problem. (partly sure)
a real scan tool can log data,  as you drive on any USA made,  (market) 1996 or newer card.  by law, OBD2, rules.
see the other persons post here with logs, for 2.3L engine in sidekick and overheats(cure custom radiator) he post huge log files in CSV  format.  (Using Excel from MS office)
The logs show what happens as you cruise. (but  will not show what CAT does, unless code p0421 pops)

if you did that we'd see how it  messes up. as  it surely   does.  

the cat needs to be close to the exhaust manifold , what manifold is there stock or not stock.(photo?) love photos... very helpful and thanks.
the now cat close to the exhaust header, keeps it LIT OFF. and working. 
and the cat must not bounce and beat itself to death. (if it rattles, IT DID)

if not kept lit off, the Cat acts as huge HC sponge, (raw fuel) and then when car goes fast or up hills the CAT wakes up and lights off, and overheats.
HC= hydrocarbons.
we know this too because one guy in LA, calif, failed smog endlessly, and exhaust was all custom, not one suzuki part there. and failed.
it failed for 1 reason, NO LIGHT OFF. CAT.  (or too big cat) in his case the cat had to be moved closer to the exhaust header end.

what suzuki did back then in the 16valve, G16b, was they had cat front neck pipe that is double walled, this helped get hotter HC gases hitting the cat, the inner wall glowing red.
The problem was, that wall, inside, melts twists and plugs the walled pipe, and kills the engine dead or near. (blocking exhaust) and SUZUKI had to recall the PIPE with TSB (have it do)

This car has complex EGR3 class setup, it has extra VSV valves, for extra EGR testing.  seen here. vsv 1 and vsv2 is gen3, 1996 added vsv 2, vacuum solenoid valve.
the new valve helps see if EGR is suck on or off.






The new EGR on this car does 2 EGR tests, (and failures tests) the 2 P0400A and P0400B tests are cruise test, and cut fuel (like going fast and foot of throttle to say stop sign test)
the system can also flag errors or dead or stuck EGR, using vsv2

i still have to look up your cat mounts... next (so it can not beat it self to death)

[fixkick]

the 1996 does not have the failing double wall CAT header pipe, but told that story only to convey the fact that CAT light off is problem on G16s.   for sure  custom exhaust end to end,
CAT to front.
what ECU do you run,  96 MT?  dash -71E11?

all this starts at ECU, then sensors,  correct sensor or wrong sensors or missing, tops list of 2nd act. (old cars or custom cars)
then CAT and last EGR. (fix EGR last or go batty)

but to do that many times I have to defeat the EGR (make it stay closed) to test all other non EGR things.  (also your custom vss must not click , not moving) or EGR will go wonky?
I think you have at least 2 problems.
1: cat NOT STAYING LIT OFF.
2: CAT BOUNCING  ISSUES, (MOUNTS MISSING FOR IT)
3: POSSIBLE egr issues, (p400 never lies) so is valid,  we can find it, for sure.  the stall test is first. do you have a hand vacuum pump? (gauge) to test vacuum devices, ?

did you know the ECU on this car even purposely sends un burned fuel to the CAT, just to keep it LIT off? yah there is that. (and tells you things, just how hard it is to keep it going and lit off )
more soon.

[fixkick]

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.