• Welcome to the Contour Enthusiasts Group, the best resource for the Ford Contour and Mercury Mystique.

    You can register to join the community.

Disabling the rear O2

B

ButtonPuncher

Veteran CEG'er
Joined
Aug 15, 2002
Messages
536
Location
Southeast WI
Under Scalars->rear_O2_sensors

Do I need to set heater_bank_1_downstream and hego_configuration both to zero?

Right now I'm getting a P0420 CEL. It also runs INSANELY rich at startup on the "Premium" tune that Brenspeed sent me.

I want to disable EGR and the lower O2 on the "Stock" tune and give that a shot.

Thanks,
BP
 
Well there is a swtich to turn off the rear O2s, then there is a separate switch to turn off the rear O2 heaters also.
Also in a separate section of the scalars is the EGR type switch. Setting it to 2 or 3 shuts it completely off.
If you don't shut all of them off you can still get CELs
 
warmonger said:
Also in a separate section of the scalars is the EGR type switch. Setting it to 2 or 3 shuts it completely off.
If you don't shut all of them off you can still get CELs
Click to expand...

2 or 3? I wonder of setting the EGR to 0 is causing the CEL. Why wouldn't 0 be off and 1 be on? More SCT weirdness.

Why would anyone want to keep the heater on but disable the sensor? I guess you could cut the wires to the PCM and run them to an AFR gauge but its after the CAT so that's useless. Again, more SCT weirdness.

Thanks,
Ben
 
ButtonPuncher said:
2 or 3? I wonder of setting the EGR to 0 is causing the CEL. Why wouldn't 0 be off and 1 be on? More SCT weirdness.

Why would anyone want to keep the heater on but disable the sensor? I guess you could cut the wires to the PCM and run them to an AFR gauge but its after the CAT so that's useless. Again, more SCT weirdness.

Thanks,
Ben
Click to expand...


Because the numbers indicate types of egr systems, not On/Off. This way the switch type (pretty sure its 3) just tells it the system doesn't exist.

The reason you have a separate switch for the heaters on the rear O2 sensor is so you can disable the sensor even though they may be left in the car. A non heated O2 sensor will be ruined if left in the exhaust. So you can disable the sensor while it is in the car...maybe for diagnostics or something and not ruin it.

But in most cases people pull them out. I just shut all the switches off for the rear O2s if someone wants them off.
 
warmonger said:
Also in a separate section of the scalars is the EGR type switch. Setting it to 2 or 3 shuts it completely off.
If you don't shut all of them off you can still get CELs
Click to expand...

Elaborate a little? I went through all the scalars and found nothing that mentioned EGR switches. I have all the heaters and switch in the rear o2 scalars turned to 0, so I believe I am still tripping a CEL because of this EGR switch.
 
posthuman63t said:
Elaborate a little? I went through all the scalars and found nothing that mentioned EGR switches. I have all the heaters and switch in the rear o2 scalars turned to 0, so I believe I am still tripping a CEL because of this EGR switch.
Click to expand...

Go to Scalars>System Switches>EGR_Type_Switch then select 2 to turn it off.
 
OK, I just flipped through my SCT manual and it also says 2 to disable EGR.

Is it something Contour specific that requires it to be set to 3? Or is just that anything 2 or over shuts it off?


BTW, that makes sense about the number being the EGR type. With it set to zero, I can still feel a little bit of surging like it's trying to activate the EGR. Not the major surging like having it set to 1 though. :)

Thanks,
Ben
 
I removed it a long time ago in anticipation of a new intake manifold for my turbo. Things have now changed and I'm going to be using a supercharger, but either way the EGR won't be used.

I also removed it because it was gunking up my intake. After removing it, I noticed a nice boost in throttle response.

BP
 
It's primarily for emissions. It also is supposed to be able to reduce knocking.

I don't see how routing 500+ degree exhaust gasses back into the intake can help anything. I guess by filling the cylinder with gasses that have already been burned (and can't be burned again), that you make the new "mixture" harder to burn. Therefore increasing your octane. Also, by not burning an entire cylinder's worth of air fuel mixture, it must reduce the cylinder temps. BUT it's all used at part throttle, and it would be a b!tch to plumb so....it had to go.

I don't want something that is GAURANTEED to gunk up my high preformance intake, just so that I might be able to reduce some part throttle knock. Knock whick I willl see on my J&S and be able to tune out later. ;)

BP
 
ButtonPuncher said:
OK, I just flipped through my SCT manual and it also says 2 to disable EGR.

Is it something Contour specific that requires it to be set to 3? Or is just that anything 2 or over shuts it off?


BTW, that makes sense about the number being the EGR type. With it set to zero, I can still feel a little bit of surging like it's trying to activate the EGR. Not the major surging like having it set to 1 though. :)

Thanks,
Ben
Click to expand...

Okay, I think it is 2, not 3. I just couldn't remember the exact number when I was posting and 99cougar put out the right number.
 
It may be 3. I just uploaded a new tune last night using 2 and it was the same as using 0. I still get a little surging after letting off the gas after hard acceleration.

I'm going to try 3 if it throws that 0420 CEL again.


BP
 
ButtonPuncher said:
It's primarily for emissions. It also is supposed to be able to reduce knocking.

I don't see how routing 500+ degree exhaust gasses back into the intake can help anything.
Click to expand...
Perhaps the fact that the cylinders are twice that temperature. The exhaust gas does cool by the time it reaches the actual exhaust pipe much less once it is routed back into the manifold via the EGR.

Also something nearly everyone forgets is that if you eliminate the EGR, via actual removal or inoperation, you have to change the timing & fuel curves. The stock setup is programmed to shut off the injectors and spike the timing when the EGR opens. Thus must folks can't figure out why they get a stumble on throttle tip in or release yet never think about the stock programming. There is a lot more going on in the code then just some simple timing and fuel curves and their associated multipliers and scalars. Hence why datalogging is a must to do anything right.
 
Argh. I should have known that disabling the EGR wasn't going to be as simple as one switch. :nonono:

I'ts going to be a couple/few months before I can afford a wideband to tune this properly.


BP
 
You must log in or register to reply here.
Back
Top