California ECU's (Exhaust Gas Tempature Sensor)

UNISA JECS · Post by **UNISA JECS** » Fri Jan 23, 2009 3:23 am

Hey Matt I was wondering why doesnt Nistune have a display for this, is this somehting that can be added/found? Asking only because Cali ECU's feed a signal to teh ECU from this sensor.

Thanks

kenbam · Post by **kenbam** » Fri Jan 23, 2009 8:48 am

Wouldnt matter anyway. Its not measuring EGT's as much as its measuring the cat temp, which can show upto a 20% increase in temps after the cat as compared to before it.

UNISA JECS · Post by **UNISA JECS** » Sat Jan 24, 2009 6:40 am

kenbam wrote:Wouldnt matter anyway. Its not measuring EGT's as much as its measuring the cat temp, which can show upto a 20% increase in temps after the cat as compared to before it.

Who knows how good it would be anyways but actually on a KA24DE its a EGR Temp sensor its basically sampling the EGT before the CAT not after the CAT.

The SR20DET is different its more closer to a real EGT sensor than the KA24DE EGR Temp sensor. Im not sur eof teh placement on the SR20DET EGT sensor, however I know its located on the CAT, not sure weather before or after its not clear to see from my source (NISSAN FAST).

SR20DET EGT sensor:

PL · Post by PL » Mon Jan 26, 2009 3:38 pm

This is very interesting. If the sensor is a K type thermocouple then we could use it as an EGT display for tuning.

This really would be a very good thing and would add another dimension to our tuning efforts.

I've seen these sensors on the factory cats and I've seen the signal line into the ECU many times. Just never thought it through. I am an idiot!!

PL

GZ@hybridka · Post by **GZ@hybridka** » Mon Jan 26, 2009 8:12 pm

The KA/SR20DE EGR sensor is a thermistor. A resistor bias circuit is used on the ecu similar to the other thermistors (CLT, IAT in some cases).

The non-california model ka24de ecu does have the pcb layout for the eg sensor but the circuit is not populated and the ADC input is pulled to ground with a jumper at c202 (capacitor is only used on the populated circuit > cali ecu). This is unlike the ka24e ecu which all have the circuit populated, but only the cali version using the sensor and associated code functions.

All ka24de ecu code have the ADC configured for this input and it can be found at ram byte &H4218. It is an 8 bit ADC with a 5v reference.

EDIT: Actually, it is a 10 bit ADC converted to an 8 bit count via ecu firmware.

The ADC input can be used as an EGR sensor, or alternative thermistor (IAT), or even as a generic 0-5V ADC without the bias circuit (map sensor, etc..)

GZ@hybridka · Post by **GZ@hybridka** » Mon Jan 26, 2009 8:20 pm

Unisa Jecs, to answer your question, only the cali ecu has the variable included in the consult stream table. Yours and most other ecus do not support this without some hacking of both the hardware and firmware.

PL · Post by PL » Tue Jan 27, 2009 9:01 am

Didn't think they'd bother with a thermocouple amp. Oh well...

PL