Secondary O2 sensor needed for Cruise control?

[mad_sb]

Originally Posted by CBR600RR

13.2 isn't "rich" mid to low 12's or 11's or 10's is rich and getting richer.

13.2 is pretty spot on IMO

not at idle.. should be targeting 14.5 - 14.7

.. some of the 32bit wrx's have similar issues even with the 02 checks turned off in the rom... hope that is not the issue... resistor packs did not solve the problem for them.

[mad_sb]

Originally Posted by DJCarbine

For pure gasoline 14.7 is Stoic, but with ethanol added (common 10% ethanol fuel) the "stoic" ratio is less. However, I still believe that the ECU has a target AFR of 14.7:1 at idle/cruise in closed loop operation

As far as I know, all cars shoot for Lambda = 1 in closed loop... unless some are compensating for 10& ethanol in their fuel, which would be around 14.2:1 stoic which may explain my "rich" readings

E10 will still show 14.7 at stoich because stoich for any fuel is lambda 1.0 and the rom is calibrated to translate that to gasolilne afr so 1.0 - 14.7.

Originally Posted by DJCarbine

Lots of good info in this thread.

Does any of the tuners on here familiar with this platform specifically know what the target lambda/AFR is during closed loop operation?

Also this is my first drive-by-wire car, so I did not expect cruise control to be disabled if there is a DTC code present... but it makes sense in a way.

This car has a closed loop target afr table set that is as low as 14.2 in some places... the actual target (easily logged with ecutek or brzedit) varries from 14.2 to 14.7 depending on a number of things (like some emissions strategy based on cat temp etc). I posted the table in my openloop / fuel trims thread a couple days ago.

[StormTrooper]

Should still be able to disable cels..... Mine and a friends 11 wrx's both ran catless and with multiple tuning solutions disabled the o2 cel.

[mad_sb]

Originally Posted by StormTrooper

Should still be able to disable cels..... Mine and a friends 11 wrx's both ran catless and with multiple tuning solutions disabled the o2 cel.

Yes, that is 100% true. Did you or your friend notice any changes to your afr? I read a bunch of stuff about the rear 02 issues etc. I assume you could adjust for it once you disable the checks etc.

@DJCarbine did you pull the codes yet just to be sure they are not unrealted? Code numbers might also help the tuner know exactly what needs to be disabled.

[DJCarbine]

Originally Posted by mad_sb

Yes, that is 100% true. Did you or your friend notice any changes to your afr? I read a bunch of stuff about the rear 02 issues etc. I assume you could adjust for it once you disable the checks etc.

@DJCarbine did you pull the codes yet just to be sure they are not unrealted? Code numbers might also help the tuner know exactly what needs to be disabled.

My tune disables/modifies the secondary catalyst checks, it ran great with no CEL for around 2K miles.

I know there is a bunch of talk in the subaru community about removal/relocation of the rear O2 sensor causing strange fueling issues, but I saw a thread on here where a member disproved this. The subaru guys seem fairly convinced that newer Denso ECUs do NOT like the rear O2 disconnected/moved out of the exhaust stream.

The codes are for O2 sensor heater circuit and no sensor activity from what I remember....

I will double check and grab the exact DTCs in an hour or so when I get home.

If all else fails, I can just run the Innovate narrowband output to the ECU, but I wanted to avoid splicing into the factory harness

[xjohnx]

You're going to need to talk to your tuner either way.

Disabling the CEL for low catalyst efficiency (which most tunes do in order to work with aftermarket headers/cat removal) does not disable the codes that will be thrown when the sensor is missing all together.

[DJCarbine]

Originally Posted by xjohnx

You're going to need to talk to your tuner either way.

Disabling the CEL for low catalyst efficiency (which most tunes do in order to work with aftermarket headers/cat removal) does not disable the codes that will be thrown when the sensor is missing all together.

I can always just plug the sensor back in and keep it out of the exhaust stream (ziptied out of sight), but there might be fueling issues according to the other subaru guys....

However, the secondary is just a switching O2 sensor, so as long as it reads leaner than the primary it should be fine.

I will do testing tonight and report back

[Jesse]

Originally Posted by FRS-Chief

Its probally a fail safe, the O2 sensors are heated and and the car will stay in open loop mode until warmed up. In this case it can't read the second 02 so it stays in fail safe not allowing cruise and running rich.

this seems on point with my thoughts.

[DJCarbine]

So with an ECUtek tune and no secondary O2, the car is actually in closed loop.
The ONLY DTC code was for an open O2 heater circuit, nothing else.

I have my O2 sensor plugged in and ziptied out of the way for now to get rid of the CEL. I am going to look into fooling the ECU with a high watt resistor for the heater circuit so I can get rid of the second sensor completely.

AFR target is 14.7 at idle, and I was hitting that.... I need to recalibrate my wideband, as it is reading off from the factory wideband

[mad_sb]

Originally Posted by DJCarbine

So with an ECUtek tune and no secondary O2, the car is actually in closed loop.
The ONLY DTC code was for an open O2 heater circuit, nothing else.

I have my O2 sensor plugged in and ziptied out of the way for now to get rid of the CEL. I am going to look into fooling the ECU with a high watt resistor for the heater circuit so I can get rid of the second sensor completely.

AFR target is 14.7 at idle, and I was hitting that.... I need to recalibrate my wideband, as it is reading off from the factory wideband

you should be able to turn off P0030, 31, 32, 37, 38 with ecutek, I have them in brzedit so i assume ecutek does as well.

[StormTrooper]

We left the sensors plugged in just deleted the cel.

[DJCarbine]

Just ordered a 6ohm 50watt resistor. Its got an aluminum body with small heat fins. I am going to try that.

[StormTrooper]

Do you have a catted midpipe? maybe buy longer cables and go around that cat vice the header one??

[DJCarbine]

Originally Posted by StormTrooper

Do you have a catted midpipe? maybe buy longer cables and go around that cat vice the header one??

No cats at all, and catalyst efficiency DTC is removed in my tune. I would just rather not weld in another bung when I have a perfectly good one that is taken up by a useless sensor lol

The resistor should do the trick, service manual says the heater circuit resistance is between 5 and 7 ohms or thereabouts. 6 ohms should trick the ECU