Sponsored
LSchicago
Well-Known Member
Well, plants breathe in CO2 and give us oxygen in return. Plant a tree and solve 2 problems.There you go. That is the best argument for removing the cats.
Co2 = bad........Right???
engineermike
Well-Known Member
From a 1998 book "Methods for Monitoring and Diagnosing the Efficiency of Catalytic Converters":
This agrees with my data during 90% of the drive cycle, except post-WOT where my exit temp is higher than the inferred cat temp.
This agrees with my data during 90% of the drive cycle, except post-WOT where my exit temp is higher than the inferred cat temp.
WildHorse
N/A or GO HOME
- Joined
- Jun 28, 2017
- Threads
- 217
- Messages
- 8,604
- Reaction score
- 6,668
- Location
- Home World: CLASSIFIED
- First Name
- ⓇⒾⒸⓀⓎ ⓈⓅⒶⓃⒾⓈⒽ
- Vehicle(s)
- '17 S550
- Vehicle Showcase
- 1
Option A: Go catless, get the rear o2 outta the stream w/ spacers & turn off COT.
Option B: Determine the melting points of the various catalysts used in the converter & raise when COT kicks in to match the lowest melting point.
But with everything being inferred, then do what Mike is doing but use a standalone COT system. Plum a couple nitrous line in or even washer fluid.. that shuts off when 'xx' conditions are met. It'll cool real fast & you don't have to worry about a over-rich condition in the engine.
Lots of ways to skin a cat if your willing to go that extra mile for something trivial.
Option B: Determine the melting points of the various catalysts used in the converter & raise when COT kicks in to match the lowest melting point.
But with everything being inferred, then do what Mike is doing but use a standalone COT system. Plum a couple nitrous line in or even washer fluid.. that shuts off when 'xx' conditions are met. It'll cool real fast & you don't have to worry about a over-rich condition in the engine.
Lots of ways to skin a cat if your willing to go that extra mile for something trivial.
Sponsored
markmurfie
Well-Known Member
The O2 sensors in the 18+ target ~110* colder tip temperature than the 15-17's do.From a 1998 book "Methods for Monitoring and Diagnosing the Efficiency of Catalytic Converters":
This agrees with my data during 90% of the drive cycle, except post-WOT where my exit temp is higher than the inferred cat temp.
The relationship in both is linear from 6% to 100% duty cycle. 0 to target temp F*. So it's easy to set a target tip temp.
You can try raising this target tip temperature to see how it effects COT lambda coming in and the inffered vs actual temperatures, as thats how the ECU uses the exhaust temp model and controls what it thinks the tempature of the catalytic converter and exhaust components are.
In a similar way to the MAF sensor with targeting a temperature in a hot wire and determining mass flow from the duty cycle needed to maintain that tempature. If they are hot, and have no duty cycle, the infered exhaust temp stays high until they cool down and duty cycle returns. Heat by its self moves slow, you need a good amount of moving mass to help extract the heat. No airflow in the exhaust, sensors will stay hot and not need duty cycle. Maybe some part throttle after a WOT will cool them quicker and get them back into a duty cycle for tempature sooner.
Not as unreliable and untrust worthy a system, as some may have you believeing, from what I can see anyway. Maybe you can log CAT B1S2 and B2S2, to have a comparison for your down stream temperature sensor.
IDK, still not sure if I would try raising the target tip temperature or lowering it first. Kinda leaning toward raising it.
Last edited:
- Joined
- Oct 23, 2014
- Threads
- 105
- Messages
- 2,408
- Reaction score
- 1,295
- Location
- Boostville
- Vehicle(s)
- 2015 Mustang(s)
Just fair warning, the cats fail on stock cars with enough abuse. Even at stock power levels.
Called the manufacturer and they said "oh you can't actually use these cats at WOT, they are only made for testing and normal driving. you should really take them off if you are going to be flooring the car".
Last set of "those" that I had a customer installed on a 800whp car... lasted about 30 min. They were very poor quality compared to something like an OEM hellcat cat. (Lucky when they failed, it didn't take out the motor, since I happened to be data logging it).
Called the manufacturer and they said "oh you can't actually use these cats at WOT, they are only made for testing and normal driving. you should really take them off if you are going to be flooring the car".
Gregory347
Well-Known Member
Are you referring to the GESI gsports or some other brand?
Grimreaper
Well-Known Member
What shows in the log when they fail or start to fail? Infered temp change or trims etc?
GR1MxREAPER
Well-Known Member
You don’t want to go with longtubes and catless midpipes I take it? Was your supercharger installed by roush and you have e a warranty or something or you just don’t want headers?
Sponsored
engineermike
Well-Known Member
The downstream o2’s start switching high/low at cruise.
markmurfie
Well-Known Member
The way I understand it,What's the proper measurement/logging procedure and how much of a fluctuation is considered normal? Appreciate a small knowledge share
The front O2's has a rich/lean switching rate that is directly from the engine operating conditions. Easily seens in the lamba PID. It changes rates with load and RPM. This switching rich/lean "depletes and fills" the catalyst of stored oxygen. Oxidation and reduction cycles of the three catalyzed reations.
To test the catalytic converter, they are concerned with its oxygen storage capacity. below a threshold of oxygen storage, and it gets reported as failed/ ineffecient.
To test this, steady state conditions need to be meet for long enough to run a test with fuel being controled by the rear O2 sensors. Theres a few steps and it will abort in the middle of any of them if conditions are not maintained.
When it controls fuel from the rear sensors, the switching should be slower the more oxygen the catalyst can store slowing the oxygen signal(transport delay) from reaching the sensors, so they overshoot lambda more than the fronts would. If this overshoot isn't enough, the catalytic converter is considered failed/ ineffiecent.
Attached is a picture of what im talking about. When they start to fail/ become ineffecient the switching becomes less noticable in the logs. Probably best to just wait for a MIL light and let the ECU do its job, rather than comb logs looking for early signs, which would actually be harder to notice the more ineffecient the catalytic converter becomes.
Of course if its temperature related and melting failure, you probably wont see signs of it in a log until after it happens and the car sounds, smells, and runs bad. Some failures they will crack first, then melt, but as far as I know when they melt, its quick with out advanced warning.
Last edited:
engineermike
Well-Known Member
See post #65 in this thread.What's the proper measurement/logging procedure and how much of a fluctuation is considered normal? Appreciate a small knowledge share
markmurfie
Well-Known Member
The problem with just looking at the rear sensors at any point in time, is they are not in control of the fuel and therefore the oxygen stored in the converter. When the fronts control the fuel, its much much faster than the rears can display, and so the rears show rich from the lack of oxygen, when really its just been bouncing around stoich. Maybe if you start seeing the rears looking exactly like the fronts, but i'm willing to bet the monitor test catch it losing effeciency long before you see that. Then typical people looking at logs will confuse lots of OL, DFCO, and PE commanded sources with a degraded converter.
Still saying this knowing you can remove them and drive a few hundred miles before the MIL is lit. Even more if you purposely avoid the staying at the steady state conditions for too long that the test runs under. Also knowing theres a second condition that can fail them, where the other precious metals lose their oxygen storage not just the cerium, which is the primary catalyst. I'll attach a pic showing good and failed, and what they look at. This is after the rears start looking like the fronts, but actual sniffer test still say emissions are good.
Then unless you had a miss for an extended period of time or some other problem know to skew lambda control to the rich side, shortening their life expectancy, the sensors are more likely to slow down and fail long before the cats become ineffecient.
Damage, like a crack, would be a really tough one, if not impossible, to spot in log. Like maybe looking at exccessive knock activity from it rattling. Nothing concrete that I can think of that is a dead give away. Mainly because it could still be functioning well enough.
Sponsored
Last edited: