EGT is on a model look up map (simulated exhaust gas temperatures) which was pre calibrated using actual egt probes pre production then information added to the map code.
As soon as a sports cats get fitted the simulated exhaust gas temperatures become incorrect.
As snippet from on of my function files. Auto translated from tech German
The simulated exhaust gas temperatures and tabgm tabgkrm (f for SY_TURBO = 1) and catalyst temperatures and tkatm tikatm be used:
1. When Katalysatoru ¨ monitoring. Falls below its starting temperature of the catalyst, then this catalyst ° F are erroneously identified as defective.
2. In the lambda control on the probe after cat This rule is only activated after the start, when the catalyst light-off his u ° is exceeded.
3. F for the sensor heater control after engine start. If the simulated dew point temperature exceeded, the probe heating LinkedIn ° can be turned on FULLY.
4. In monitoring the probe heating ¨. Via the exhaust temperature falls below for example 800 ° C is then the probe heating
off, so that the probe is not too hot.
5. Fu ¨ r ¨ ftersteuerung the Motorlu.
6. F for switch-protection components.
This function provides only a rough approximation to the curve of the exhaust gas temperature and catalyst temperature, by the application especially the four ¨ monitored area (Taupunktverla ¨ UFE in the exhaust, Katalysatoru ¨ monitoring, probe heating mode or switch-off and high temperatures fu ¨ r component protection ) should be viewed critically.
1. Basic function
Stationary temperature (tatmsta): The same applies for takrstc
With the N / RL map KFTATM the stationary ¨ re exhaust gas temperature is set before catalyst.
Corrected, this temperature over ambient temperature or Umgebungstemp.Nachbildung characteristic ATMTANS
in shear with the fixed value TATMSA,
catalytic converter heating at the fixed value TATMKH in Katwa ¨ with the fixed value TATMKW, with the ignition undwinkelwirkungsgrad map KFATMZW Preheat temperature = f (ML, ETAZWIST) with the lambda setpoint map KFATMLA Temperature = f (ML, LAMSBG_W) and
with a cold engine block (TMOT - TATMTMOT) with TATMTMOT = 90 degrees C. The Kattemperatur (exotherm) is corrected with
Temp elevated heights with the characteristic KATMEXML or KATMIEXML = f (ML)
Temp decrease with KLATMZWE or KLATMIZWE = f (etazwimt) Closed · ndwinkeleinfluß with KLATMLAE or KLATMILAE = f (lambsbg_w) Lambda influence
Temp set to TKATMOE or TIKATMOE at tabgm <TABGMEX or B_sa = 1
F for tikatm the temperature in the catalyst and the temperature after the catalyst tkatm kó · can different temperature increase by exothermic reactions and cooling and also different be applied Closed · ndwinkel and lambda corrections.
The temporal influence of the temperature before Cat:
Using a PT1 filter (filter time constant ZATMAML) the dynamics of the exhaust gas temperature and is reproduced with the PT1 filter (time constant ZATMRML) the dynamics of the tube wall temperature.
With the distribution factor FATMRML the exhaust gas temperature and the tube wall temperature is weighted.
The Kattemperatur is tkatm tabgm from gas temperature along with the PT1-filter (filter time constant ZATMKML) was calculated.
Via three filters (time constant ZATMIKML) is out of the exhaust gas temperature, temperature in catalyst tabgm modeled tikatm
(Principle Wa ¸ rmetransportes). In shear, there are hung by the small air mass flow in the catalyst, a the Potential Abgastemperaturerho ° by the large ¨ Full-Size Effect of temperature on the monolith by stro ¨ Mende exhaust. This increase in Temperaturerho ¨ thrust can be modeled by B_sa is initialized with the positive edge with a temperature which is composed of the Kattemperatur tikatm and eı'nem offset TATMSAE.
The time constant of PT1 filter ZATMIKML are shown with luftmasseabh-dependent characteristics.
The initial values fu ¨ r exhaust and catalyst temperature can be calculated from the temperatures at engine start at the parking and the run-time. The initial values fu ¨ r exhaust and catalyst temperature should correspond to a few minutes about the downtime required tube wall temperatures at the probe insertion points.
The filter for the exhaust temperature is stopped at B_stend = 0. The filter fu ¨ r is the tube wall temperature stopped
is to B_atmtpa = 1. Only when B_atmtpk = 1, the filter for is released, the catalyst temperature.
