Question about Resistor Mod for EGR delete
05-08-2010, 06:18 AM
#1
Question about Resistor Mod for EGR delete
i am throwing a EGR code on my 4th gen after a DEK swap..
I have a 95 SE 5spd ECU installed.. that eliminated the IACV codes but my EGR code is still triggering the CEL
I did a bit of research and i found that the 240sx guys did a resisitor mod for the EGR delete.
I want to know if there is a resistor mod for us 4th gen.. if there is. please chime in and spill some info.. If not then i have no choice but to install my EGR back into my max and call it a day.
I need to clear the CEL before NOV for my inspection..
experts, time for you guys to shine again
I have a 95 SE 5spd ECU installed.. that eliminated the IACV codes but my EGR code is still triggering the CEL
I did a bit of research and i found that the 240sx guys did a resisitor mod for the EGR delete.
I want to know if there is a resistor mod for us 4th gen.. if there is. please chime in and spill some info.. If not then i have no choice but to install my EGR back into my max and call it a day.
I need to clear the CEL before NOV for my inspection..
experts, time for you guys to shine again
05-11-2010, 06:16 AM
#3
Unfortunately, I don't think you can just replace the temp sensor with a fixed resistance.
The resistor mod works for the knock sensor because the sensor itself has a resistance, and the ECU checks that resistance periodically to make sure the sensor is connected, and there is no short or open in the circuit. Just plugging in a resistor in place of the KS will never generate a knock signal, and it will keep the ECU satisfied that the circuit is operating correctly, keeping your timing advanced.
The EGR temp sensor is a resistor that changes value with temperature in a predictable way (a thermistor). However, the ECU will look for different values depending on whether or not it is telling the EGR valve to open. A higher temperature will produce a lower resistance (negative temperature coefficient). In other words, if the valve is closed, the ECU will expect a high resistance, while if the valve is open, the ECU will expect a lower resistance. So just putting in a fixed value will make the ECU think that it is reading a constant temperature, and it will turn on the MIL because as the ECU tells the valve to open or close (even though it's not there) it will expect the temperature to change.
The only work around I could see for deleting the EGR is to hook up a relay to the power for the EGR solenoid valve and use that relay to switch between different resistances to trick the ECU into thinking that when the valve is open, the resistance is lower (EGR open, hot condition) and, conversely, when the valve is closed, the resistance is higher (EGR closed, cold condition). Because the solenoid directly controls the valve, it will have a direct effect on the resistance of the temp. sensor. What values to use would have to come from a measurement of the resistance of the temp sensor in a working system: one reading from when the valve is open, and one from when the valve is closed.
Nonetheless, there is one caveat to deleting the EGR. Even though your MIL would be off, your NOx emission may be high enough to fail. I think each state is different in how they test emissions so you might want to check to see if they physically sample the gasses from your exhaust.
The resistor mod works for the knock sensor because the sensor itself has a resistance, and the ECU checks that resistance periodically to make sure the sensor is connected, and there is no short or open in the circuit. Just plugging in a resistor in place of the KS will never generate a knock signal, and it will keep the ECU satisfied that the circuit is operating correctly, keeping your timing advanced.
The EGR temp sensor is a resistor that changes value with temperature in a predictable way (a thermistor). However, the ECU will look for different values depending on whether or not it is telling the EGR valve to open. A higher temperature will produce a lower resistance (negative temperature coefficient). In other words, if the valve is closed, the ECU will expect a high resistance, while if the valve is open, the ECU will expect a lower resistance. So just putting in a fixed value will make the ECU think that it is reading a constant temperature, and it will turn on the MIL because as the ECU tells the valve to open or close (even though it's not there) it will expect the temperature to change.
The only work around I could see for deleting the EGR is to hook up a relay to the power for the EGR solenoid valve and use that relay to switch between different resistances to trick the ECU into thinking that when the valve is open, the resistance is lower (EGR open, hot condition) and, conversely, when the valve is closed, the resistance is higher (EGR closed, cold condition). Because the solenoid directly controls the valve, it will have a direct effect on the resistance of the temp. sensor. What values to use would have to come from a measurement of the resistance of the temp sensor in a working system: one reading from when the valve is open, and one from when the valve is closed.
Nonetheless, there is one caveat to deleting the EGR. Even though your MIL would be off, your NOx emission may be high enough to fail. I think each state is different in how they test emissions so you might want to check to see if they physically sample the gasses from your exhaust.
Thread
Thread Starter
Forum
Replies
Last Post
bryants95max
4th Generation Maxima (1995-1999)
10
10-02-2015 12:52 PM