For some reason I cannot get this to work, Maybe I have the wrong resistor its a 10kohm (1 megohm) 1/4 watt resistor. Any suggestions? USDM EVO9.

 

resistance of the rear 02 sensor is around 20 ohm and according to mitsu service manual the ECU will trigger an error if the current is under 0,2 amp (corresponding to 14 volt in a 70 ohm resistor)
What I have in my car is a 47 ohm resistor 5 Watt model (5 watt is manadatory otherwise the resistor will blow) . Take care to put the resistor away from anything that can burn because its getting hot)

 

x1000000

 

So why was it stated by the O.P. to use a 10kohm 1/4 watt resistor? So if I put a 47ohm 5 watt resistor in there I should be good to go?

Thanks for the help.

-George

 

ECU needs to see O2 sensor heater current to keep CEL happy. When O2 heater current falls below certain level ECU assumes that O2 sensor heater is not functional or disconnected. To simulate O2 heater current you need to use adequate load. 47 ohm resistive load keeps ECU happy in most cases. I=U/R so at 12V the load pulls 0.25A of current and at 14V 0.3A. P=U*I so at 14V the resitor will dissipate roughly 4.2W of power. It will get hot. Using a 5W rated resistor is this case is not a good engineering practice. A resistor should be derated by 50%, so use 10W ceramic resistor. It won't cost more than 5W but live a long happy life. Electronic components needs to be derated. This is how we design all of our electronics.
BTW you can also connect two 22 ohm 5W resistors in series. The wattage rating will double and 44 ohm load will keep the ECU CEL happy.

 

^^^ Good info! Thanks for the informative post.

-George (On his way to RadioShack )

 

I found a 50 ohm 10 watt ceramic resistor, Will this work fine?

Thanks,

-George

 

Bumper for my questions above ^^^

 

47 or 50 ohm. Pretty much same animal since those resistors are 5% or 10% tolerance.
This is only taking care of O2 sensor heater load. You also need to give the ECU right O2 sensor signal.

 

Sounds good just wanted to make sure before I try it. I beleive the code changed in the .xml file should take care of the 02 sensor check.. I hope

Thanks Zeitrnoix!

 

Thanks to zeitronix

 

im about to upload the code to turn the rear O2 off...heres hoping

 

soo im digging through this thread and i noticed that some had said earlier that you wont pass emissions if you do this mod. i just wanted to confirm this, i have an usdm 05 evo 8 if that would make any difference. thanks!

 

No one that I am aware of has tried to pass emissions. Theoretically it wouldnt pass the readiness tests, though I still see the voltage from the rear O2 sensor. It would be interesting if someone had a "guy" that could do the OBD test and see without having a full test done.

 

It wouldn't pass emissions. To see for yourself, just use Scantech to look at the readiness tests.

Most states won't pass you if your cat efficiency is not ready.


Eric