Since this rom works for all evo8's now, I figured I'd steer everyone's attention towards this! Thank you logic and others who have worked to get this solved! I am merely a tester and wanted to get the word out

We've already been able to get around the standard CEL that comes with a testpipe through an earlier patch that is now standard in Tephra's ROMs, but some of us have re-used the wiring harness running down under the passenger seat for a wideband and want to completely eliminate the rear o2. Without the following, you'll still get a CEL because the heater circuit will be broken.

Starting here in the IX rom thread:
https://www.evolutionm.net/forums/7302505-post266.html


Changed "4A0B" to "0009" (i.e. 0x0009) and that's it.

I tried it, it seems to work great! I have the rear o2 completely unplugged. I'll make sure nothing silly becomes of it over the next week but all seems fine for now.

 

There is another rear O2 heater CEL fix for this same ROM.

Address 2c61e, broken down into 8 bits using blob bits and you change bit 4 from 1 to 0.

Any idea what the difference between these two methods is? I'm using the OBD-II force pass with it and I do not get a CEL for the O2 being completely removed. I am also datalogging my wideband through the rear O2 channel. I just passed an OBD-II inspection as well using it.

 

Can anyone translate over to 94170014/15? It would be too much work for me to migrate over to 96530006.

 

honki24: See the link that scheides posted in the first post, I documented the patch for 9417015 there.

Also, the version that 03whitegsr is referring to (for 96530006) is here; I'd probably consider that a better long-term version than my original patch, since it means there's no "patching" per-se, just a toggle. (ie. You could add that to any old 96530006-based XML, and you're off and running.)

03whitegsr: the difference is that my original version just replaces the branch that jumps to the O2 heater routine with a NOP (ie. "do nothing"), while acamus' approach makes a more subtle change earlier in the code (similarly to how the baud rate is changed), such that you only have to toggle a single bit to make it work. I'd consider his to be "better", in that you don't need instructions to accompany it, hence it's easy to enable or disable for the lay-person.

 

logic, is there any functional difference between the two? With the stock hex code and the new hex code in the one in my first post, its about the same as a toggle switch as far as I'm concerned. It's not literally '0' and '1' but close enough

I may have to give the other code a try too!

 

Thank you Logic.

 

Functionally, they do the same thing. If you already have one that's working, might as well go ahead and leave it.

 

So the stock rear O2 sensor is purely for emission purpose?

 

Correct.

 

Will this work on a 94170008 rom?

 

Click the link, there are more rom id's listed in there, but you should be running tephra v7 and 96530006 anyways

 

So if you do this mod does it not effect the fuel trims ability fo function properly?

See this thread

 

Not so straigth forward,

MUT_60_Rear_O2_Trim_Low
MUT_61_Rear_O2_Trim_Middle
MUT_62_Rear_O2_Trim_High

Gives you an idea why mrfred's simulator is necessary.

 

You know, I've been using some variation on mrfred's rear O2 simulator for so long that the fact it was there completely slipped my mind.

My apologies, acamus is right: it has an effect on trims, unless you're running mrfred's rear O2 simulator. It comes with any of tephra's recent releases (5.10 and higher at least, possibly earlier).

 

has anyone wired in the heater circuit for the wideband through the rear o2 circuit? or does it look like it may draw too much amperage?