What is Cat OverTemp Protection?
Copy & Paste Moderator
Joined: Apr 2002
Posts: 9,764
Likes: 208
From: Eastern MA
Re: What is Cat OverTemp Protection? If I remember correctly, an engine running rich runs cooler than an engine running lean. So it makes sense that the Cat Overtemp Protection would dump more fuel into the engine.
--VIP1
--VIP1
Staging Lane
Joined: Aug 2002
Posts: 55
Likes: 0
From: Plano, Texas
Re: What is Cat OverTemp Protection? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by VIP1:
<strong>If I remember correctly, an engine running rich runs cooler than an engine running lean. So it makes sense that the Cat Overtemp Protection would dump more fuel into the engine.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Agreed, specifically, exhaust gas temperature.
<strong>If I remember correctly, an engine running rich runs cooler than an engine running lean. So it makes sense that the Cat Overtemp Protection would dump more fuel into the engine.</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">Agreed, specifically, exhaust gas temperature.
Staging Lane
Joined: Aug 2002
Posts: 55
Likes: 0
From: Plano, Texas
Re: What is Cat OverTemp Protection? </font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">In Team-ZR1@y..., "Team ZR-1" <teamzr1@t...> wrote:
....The most I can find in GM manuals is :
Converter Protection Mode: The PCM constantly monitors the engine operation through inputs such as the oxygen sensor, and estimates conditions that could cause the catalytic converter to reach excessive temperatures. If the PCM determines that a converter overheat condition may occur, the system returns to open loop, and enriches the fuel mixture which, in turn, cools the converter.
Thus if you use your scanner and see the PCM go out of the norm of being in closed loop ( once engine is at normal operating temps) then you know COT has been triggered and then I would suggest tuning COT table, if you do not see a switch to closed loop I would not muck with COT for it could cause damafe to cats.
I researched FORD and found :
Catalyst Temperature Model
A catalyst temperature model is currently used for entry into the catalyst and oxygen sensor monitors. The catalyst temperature model uses various PCM parameters to infer exhaust/catalyst temperature. For the 1998 MY, the catalyst temperature model has been enhanced and incorporated into the Type A misfire monitoring logic. The model has been enhanced to include a misfire-induced exotherm prediction. This allows the model to predict catalyst temperature in the presence of misfire.
The catalyst damage misfire logic (Type A) for MIL illumination has been modified to require that both the catalyst damage misfire rate and the catalyst damage temperature is being exceeded prior to MIL illumination. This change is intended to prevent the detection of unserviceable, unrepeatable, burst misfire during cold engine start-up while ensuring that the MIL is properly illuminated for misfires that truly damage the catalyst.
Thus it is misfire damage they are concerned about and use COT to save the cat from damage.
JR
Team ZR-1 Consulting Services
http://teamzr1.com/main.html
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">
....The most I can find in GM manuals is :
Converter Protection Mode: The PCM constantly monitors the engine operation through inputs such as the oxygen sensor, and estimates conditions that could cause the catalytic converter to reach excessive temperatures. If the PCM determines that a converter overheat condition may occur, the system returns to open loop, and enriches the fuel mixture which, in turn, cools the converter.
Thus if you use your scanner and see the PCM go out of the norm of being in closed loop ( once engine is at normal operating temps) then you know COT has been triggered and then I would suggest tuning COT table, if you do not see a switch to closed loop I would not muck with COT for it could cause damafe to cats.
I researched FORD and found :
Catalyst Temperature Model
A catalyst temperature model is currently used for entry into the catalyst and oxygen sensor monitors. The catalyst temperature model uses various PCM parameters to infer exhaust/catalyst temperature. For the 1998 MY, the catalyst temperature model has been enhanced and incorporated into the Type A misfire monitoring logic. The model has been enhanced to include a misfire-induced exotherm prediction. This allows the model to predict catalyst temperature in the presence of misfire.
The catalyst damage misfire logic (Type A) for MIL illumination has been modified to require that both the catalyst damage misfire rate and the catalyst damage temperature is being exceeded prior to MIL illumination. This change is intended to prevent the detection of unserviceable, unrepeatable, burst misfire during cold engine start-up while ensuring that the MIL is properly illuminated for misfires that truly damage the catalyst.
Thus it is misfire damage they are concerned about and use COT to save the cat from damage.
JR
Team ZR-1 Consulting Services
http://teamzr1.com/main.html
</font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">
