RoxyCarter

creating a tangent thread to the info we already have covered in the "Stock Cats" thread in the z06 section.

to catch everyone up, car's computers receive temp readings from the downpipe 02 sensors, and when these readings and other internal engine readings pass certain thresholds, the cars pull timing and run extra rich to try to cool the cats back down

this is a good And necessary program for those who have cats.

for those that remove their downpipe cats, via a norcal or AFE catless downpipe, or run catless LT headers, and wish to retain the Stock tune or who own a 2019 zr1, where tuning is not an option yet...

..then in all of these cases, the Stock tune pulls timing and runs rich, which is an unnecessary power limiting program, since there are no cats that need protecting.

the solution is to cap the exhaust o2 sensor temp readings to avoid COT.

we have theories on how to accomplish this, but wanted to double check and make sure we were not reinventing the wheel, and wanted to see if anyone else already has a working viable solution for purchase.

please understand, big daddy 02 sims do not kill COT from occuring, at least not in our observations.

Thank you

Amirns

What is a COT, I had the afe downpipes so i might be able to help if I know what it means

RoxyCarter

Amirns

I didnt record any data on for the COT when I had them on my car but I did use the bigdaddies 90 degree angled sensor and didnt get any codes. I drove the car very hard at times for 10-15 mins (canyon runs) and didnt feel the power go down at all, and for WOT on the straight the car picked up alot of power in the top end, for example there is a straight after a specific corner and I always hit 120 ish before braking but after the afe downpipe I would hit 135 to almost 140 mph

RoxyCarter

Thank you for the real life experiences. Were your afe pipes the high flow cat or the catless versions?

RoxyCarter

Sorry for all the spelling errors earlier... if you refresh the page, they are fixed.

don't text and drive

Amirns

Mine were the catless pipes but since I had a borla catless xpipe and the magnaflow mufflers they were REALLY loud and very droni so I took them off and put them up for sale here, but I bought a corsa system and once that gets installed on the car I might put the afe's back on the car since they say corsa's dont drone, because I absolutely loved how much power it gained and how noticeable it was, if I do put them on and they still drone then I will most likely buy the one with highflow cats from afe. If your thinking about pulling the trigger do it and dont waste money on the full exhaust

cajunboyz

Very informative

RoxyCarter

agreed, thank you guys for the input.

long story short, a circuit has to be made to limit the voltage readouts... or keep them above a certain voltage as i think the o2 are reverse scaled, and hot is lowest voltage.

all that said, while we speculate this will eliminate cot... it is still possible that the engine temps and wot durations may override things anyway....

and that is why I am searching for knowledge... it's not that we think it's impossible for us to do... We think it may be a waste of time, and fruitless, so we wanted to put out a feeler thread to see what others have already tried.

dar02081961

You may want to look into this a little further.
It is the general consensus that Cat Temps are calculated using algorithms based off of inputs from a variety of sensors.
I believe the 02 sensors are standard narrow-band 02 sensors which alone offer very little information related to temperature.

Not saying what you are proposing wont work, but it might be best to determine how much affect the 02 sensors actually have on CAT temps at WOT.
Not sure how you would go about this without affecting closed loop performance since the 02 sensor switching is key for fueling in closed loop. (assuming as you stated you don't want to alter the factory tune).

RoxyCarter

I do agree with you, and this is what I was speaking about above.

that being said, it is possible that the car has 2 separate programs, and only IF the o2 temp signals are missing, THEN it goes to the internal algorithms as a backup to calculate for COT.

we absolutely agree these algorythims are there that monitor engine temps and wot data, but we ALL seem to only know it is there AFTER the o2s have been disabled.

There is the slight possibility that the computer and tune, in the sections off limits to hp tuners... it is possible there is an OR situation in the programming, and once 02s are absent, it flips to the internal algorithms

most cars watch real time o2 for accurate cat temp data. It's odd to think Chevy would not do the same on the vette.

but again, you may be absolutely right, and it could absolutely all be a waste of time to cheat the o2s

Mikec7z

to the best of our knowledge, the o2 sensor is sensing both o2, and also heat... and we think it has 2 return signal wires, one wire sending back a signal for each. As you say, we would not want to mess with the o2 readings, just the temp readings.

Higgs Boson

dar is correct, it is a calculated/inferred value in the tune. you can easily disable or edit this in the Z06 but the ZR1 is still locked down.

Mikec7z

we agree it is in the tune, and a calculated value when the o2 sensors are disabled or absent... but are we 100% certain that when they are reporting, the ecu is not utilizing their readings in real time?

Similar to closed loop vs open loop... its going to utilize the best reading it has, but if the best is not there, it falls back on the lesser accurate reading/calculation in case customers cars o2 sensors go bad, etc, as in real world failures.

Do we KNOW that the car does not look for o2 sensors readings, first?

dar02081961

Mike I understand your angle.
However I don't believe our 02 sensors deliver any temperature information.
They only deliver a voltage reading between .1 and .90 volts. That is all it does.

What I am getting at is this.

As far as I can tell our 02 sensors are standard 4 wire sensors.
The wires are: 2 for the 02 heater, 1 for the ground and 1 for the switching signal the PCM uses.

This being the case the only temperature information these sensors can give you if any at all must be derived from the switching signal.
In other words they don't detect temperature at all but the information they provide is likely used in conjunction with other info from other senors to extrapolate a cat temperature. The 02 sensor itself has no way to tell you what the temperature of the exhaust or CAT is. It isn't wired to do so and it isn't a temperature sensor by design.

If this is in fact true (and I believe it is) this means your theory of the 02 sensors being THE primary player in CAT temp calculations cant be true.

Any tampering to/with the 02 sensor may or may not help you to your goal of fooling the PCM into thinking the CAT temp is lower than calculated and thus keep you out of COT protection.
BUT regardless if your approach does or does not work it will likely affect the 02 signal during closed loop as well.
Therefore unless your approach is only active at WOT and leaves the normal 02 signaling unaltered during closed loop operation its not a viable approach to achieve your goal.

JMHO

HessViper

what you just said was our first assumption, but a head tech at a dealership kept insisting to us that they do report temp.

We sat back and started counting wires ourselves.

What we came back with was, the only way they can measure heat is if, 1 wire is ground, 1 wire is hot, and the 2 return wires are 1 for o2 and 1 for temp... and it would have to have a built in mechanism to turn on the "heater" if it was below a certain temp.

Otherwise, we agree with you, others have insisted that we are wrong that they could not measure heat, so we are starting to explore that angle also, just to be sure.

Thank you for the input, and if you can absolutely say that is the case, and provide the evidence/understanding for us, then we will appreciate it greatly.

Higgs Boson

if you consider that you can disable COT by lowering the temperature values in the inference table when leaving the O2 sensors in and functional it stands to reason that the tune values are not safety/fall back values and are the primary driver in what the ECM thinks the cat temps are. it works the same way with ford and dodge, range rovers, mercedes, etc. there is really nothing to figure out in this regard, it's just how it works.

the four wire sensor uses one wire to send a voltage signal (for the rich/lean situation), one wire to ground the sensor, one wire to power the heater, one wire to ground the heater.
the O2 sensor is heated so that it works (accurately) faster and can be placed in a wider range of locations (doesn't have to wait to get hot by the exhaust and placed specifically to maintain a specific temp to work accurately).

has nothing to do with reporting any temperatures (in fact an O2 sensor doesn't even report directly to the ECM anyways) and if you know a technician, especially a head one, that thinks it might.......run.

ronsc1985

I think part of the confusion with this has to do with what is called ground. On long signal runs with small voltage swings it is common to use two wires, one for the signal and one for the reference level. I may be called ground but actually the signal is sensed deferentially between the two wires. The wires are either twisted par or close to each other such that any magnetic field or capacitive coupling to these wires hopefully affects both wires the same such that the difference between the two is not affected much if at all.

I have no idea if this is how the oxygen sensor is wired but for a critical signal like this it would be best practice to do so.

The long and short of this is ground is not the same level throughout the system and for signals with rather small magnitude relative to other signals differential sensing is appropriate.

Mikec7z

the way you describe the programming, leads me to believe you are correct and that the o2 sensors do not play a role in cot.

I will however, just to be certain, propose at least 1 more scenario (i might think of more later also, so forgive me), and let me know if I am incorrect on this first one.... and I realize you already went over it above, but i really want to be sure we are not just assuming and this has actually been tested thoroughly.

I believe and agree that the parameters that you are able to edit in HP tuners, do affect the internal algorithms, but have you ever edited these parameters, and then left the o2 sensors in, and kept them active in the vehicles decision making and COT turned on? (it seems most people when they tune the vehicles, disable the o2's and/or cot, is this correct?) anyway, you see where I am going with this.

And i had a mental laps earlier to not discuss the 4 wires better. The lead tech I am friends with, ironically has the opposite stance that you do, and I have even ran your thoughts past him AGAIN (as your thoughts are identical to my original thoughts were a few months ago) And he says the wires and their functions are as ronsc1985 mentions, more than meats the eye, and that one is a heat/temp signal wire back. Anyway, the tech friend of mine, swears that this IS how o2 sensors measure heat, and most brands do it, and he specifically pointed to the hellcat, and to the demon, and said both utilize the o2 sensors first to calculate for cot, and only if something is disabled, or not responsive, does it then internally calculate for cot.

I am not trying to prove i know more than you, ironically, you and I agree on this, but due to his persistence, I feel it is a stone that we should not pass by without making 100% sure we turn it over and really test to see if he is correct.

IF he is correct, this WILL be a game changer for "tuning" vehicles moving forward, and not actually cracking the tune... nor voiding warranty...

Reason being, we can utilize the signals that INITIATE COT, and have that signal wire from the 02, pass through a 3rd party controller, like the crawford racing controller or a holley, etc, and as power adders are added to a stock tune vehicle, and IF the stock tune vehicle ever begins to run lean, THEN we can program the crawford racing control unit or holly to initiate the signal to the stock ecu, which initiates cot, and then the car will drop a 1.5+ afr points as a result... and run more rich from where it was a moment earlier... we can literally use COT ON/OFF to have 1.5 afr CONTROLLABLE swing in AFR... without ever using HP tuners or voiding the warranty of a vehicle.

...

now you might start to fully appreciate the magnitude of how important this is to fully investigate... as the c8, may not be able to be cracked by hp tuners, and us solving this now, would make it so that we don't HAVE to crack the c8 stock tune, to be able to run larger turbos or change the waste gates and BOV on their turbo setups... we can tune the car's afr by lying to it when it does and does not need COT, and we remove the cats so that our lies dont hurt the cats and clog the exhaust, and instead only swing the AFR's in our favor, to keep the car close to 12.5, and do so on our command.

Mikec7z

where do the o2 sensors report to, and how would the ecu absolutely NOT get their temp signals, if they did happen to be sending them?

I appreciate you taking the time to explain all of this to me, I've been busy with other projects, and have not had time to investigate all of this myself yet.

I'm just the outside the box idea guy... and then we attack the ideas to see if they are viable, and i truly appreciate your help attacking.

Combine this with a map readout manipulation, and a MAF manipulation, and i feel it is possible to tune a car, with a 3rd party box... where all of these signals go through first. We may even figure out a way to middle man fool the trans and the engine and ecu from communicating correctly, so that demanded torque values can all be mapped and skewed as well. Sure it will be a total bitch nightmare to do it all this way, but those of us smart enough to do it, will be the heros when cars can no longer be "tuned" if GM has their way.

Worst case, we figure out an alternative to the current procedures of tuning, and we just offer a second option where a person can pull it all back off their car, and GM, never knew the car was making 1000 hp a day ago. 500 torque can be code for 1000 torque, but as long as everything that would report 1000 torque instead reports 500, then how would the car ever log 1000? The hacking the transmission and working with people like crawford and weapon X after the transmissions and TC are hacked and organized and easy to tune by a non mad scientist... will open a new world of possibilities.

Worst case, a person just installs an aftermarket built trans which can be pre loaded with all the necessary reduced ratios of power reported back to the stock ECU.

We can add the fueling via port injection, etc. The trick is in keeping the car from knowing it is actually making the power it is making. Sounds bizarre, I know... but i do believe it is all possible.

There will eventually come a point where GM and other manufacturers start charging so much premium for even 100 more HP, and the aftermarket community wont be able to do anything to compete because the cars ecu will be so well locked up tight with encryption

So while all of this may sound very expensive, understand, the alternative the manufacturers will offer will be much more expensive. Look at the price gap between a z06 and a zr1... for 100 more HP. This price gap is only going to continue to increase as manufacturers feel confident no one can make their z06 level model as fast or faster than their zr1 models, so to speak.