mgrotel

iTrader: (3)

interesting, good to know. seems like nissan would have wanted to use the faster, higher resolution ones all the time. interesting

tollboothwilley

iTrader: (8)

Well damn. It seemed like I had lower fuel mileage since I swapped to ART pipes...maybe this is why

The question I have is: If the rear O2 do function to control part throttle does un-catalyzed exhaust (throws a CEL) change the function of those sensors as well? Whether you block the CEL code or it is kicked from using test pipes does it throw off the sensors values for Stoich ?

djamps

iTrader: (1)

The P04x0 codes (catalyst) do not change the function of the sensors even if the codes are deleted.

psycobusa

I'm having the same problem on my 06 G coupe with ARTs.

So the answer I'm getting from reading this thread is to cut the bung extensions off of the ARTs and weld on regular bungs. When the codes pop up which state your cats are no good (the reason for the bung extension in the first place), get uprev to delete the codes.

This will stop you from getting lean codes and also shiddy mpg. Did I get all that right? Is there anything I'm missing?

djamps

iTrader: (1)

Assuming nothing else is wrong (cracks / leaks) yes that should solve the bad mpg and lean codes.

e30cabrio

iTrader: (30)

I have arts on a fully built stroker and have had no codes for over 2k miles.

The only codes I had were due to cracks in the extenders and failing 02s.

I get reasonable mileage and good power.

F2CMaDMaXX

iTrader: (2)

Interesting, other than the Nissan tech, do we have anything else confirming when the rear or downstream O2's are being used?

Is there anything in the UpRev tune than can just turn them off?

djamps

iTrader: (1)

My own experimenting and logs have confirmed it, even before I talked to a nissan tech.

BUT who knows how each year or ECU revision operates.. I'm only going off my experience with an 04.5, which is the 1st model with factory widebands.

Would be cool if others with different model year(s) and Cipher could do some tests like I did. Take some freeway cruising logs of your A/F and corrections, at least 30 min long one with and one without extenders/antifoulers.

Even without lean codes, it should be fairly evident in the A/F readings moving around more or less.

And no, there isn't any way to disable o2 sensor functionality -- just codes. You could try to remove the sensor if you don't want it being used. I don't know what other side affects this may cause though.

F2CMaDMaXX

iTrader: (2)

Ok well I have an 04.5 as well, you just want af and the the long terms?

djamps

iTrader: (1)

There's no long term trims in the logging options. But at a minimum..

a/f both banks
a/f correction % both banks
sensor 1 (volts) both banks
sensor 2 (volts) both banks

Reset your fuel trims before hand then take a good highway drive on cruise control at normal speeds like 65mph for at least 30 minutes on each log.

F2CMaDMaXX

iTrader: (2)

I could have sworn i saw long term when i last had a look round. However, i'm not so familiar with the Osiris just yet.

I can't do a 30 minute drive at the moment, but i will try and get some constant cruising in, are you only seeing the problem after 30 mins?

(We don't have 65 limits here )

What should i be looking for in the logs?

djamps

iTrader: (1)

The thing to look for is A/F to dip below 14 under light throttle conditions. It won't happen all the time, but is almost certain to happen once cruising at a steady light-throttle pace over 50mph for a while. Mine would slowly creep from 14.7 to 12-13 on a steady cruise, and the correction % would go over >100 at the same time (opposite of what it 'should' be doing). Goosing the throttle or accelerating would pop it back to 14 and corrections back to 100%.

F2CMaDMaXX

iTrader: (2)

OK, i'm gonna check them out soon, however, i thought this was interesting;

From the manual:

I cannot find the definition of "switched" and the so far as i understand the second part, it means it should never happen under the circumstance you're describing, either

djamps

iTrader: (1)

Ya... under 'normal conditions' but would you consider exhaust mods 'normal' conditions? The ECU sees different inputs than if you had stock cats. Don't forget this straight out the FSM:

stoichiometric happens under light load. Medium to heavy load would not be stoichiometric.

what I am thinking, is that 'normal' conditions may mean when sensor 2 indicates an expected range when compared to sensor 1. In the case that sensor 1 and sensor 2 aren't within a certain range of each other, the ECU will actually favor sensor 2 in bringing A/F to stoichiometric.

why the ECU would favor sensor 2 over sensor 1 in abnormal conditions... there could be many reasons... and we still don't know if this behavior is the same for newer models. Does anyone have newer FSM's that could compare the descriptions of sensor 1/ sensor 2?

Neimad

ECM has to keep emissions levels within spec and secondly keep the cats alive as long as possible. It will use whatever sensor makes most sense at that time and place to achieve these results. The AF sensors and the exhaust valve timing are used to reduce NOX so sometimes it's messing around with stuff too. It really is an amazing system when you consider how much power you get stock with all this crap fighting you.

mgrotel

iTrader: (3)

so, i think its safe to assume that strictly having test pipes and no cat at all, this would qualify as NOT "normal conditions". which means then the #2 sensors are defintely being used for engine control. next question, does the fact that there are no cats on the car affect how the #2 sensor is reading, and therefore how it adjusts the engine? are the test pipes throwing off their readings so far that it cannot adjust the engine like it was designed?

djamps

iTrader: (1)

So far I've only seen A/F control issues with sensor2 being completely out of the exhaust stream, not just the simple fact of deleting the stock cats.

Neimad

Of course, it's all pissed off and confused. If cat's are there and you are not WOT if is constantly going rich/lean/rich/lean. Cat has three elements inside, platinum, rhodium and the one I always forget on test day. Lean feeds cat 02 which one element holds, then the HC comes and the heat and other element burns it into somewhat harmless CO2. The other element is used to strip the NOX back into N and make more CO2. Engine with cat should have 14.7-15.2% CO2 and 74%ish N plus some trace crap that we don't worry about.

If you remove your cat's get a tune that ignores rear 02 function and uses AF sensors obtain ideal air fuel ratio for power production. I want a throttle cable too damn it.

F2CMaDMaXX

iTrader: (2)

I read it as, if there is a problem, i wouldn't necessarily think that normal conditions would change by removing the cat.

Remember, this is referring to sensor 1 (upstream), only if there is a problem there, does it switch to sensor 2 (downstream) for it's readings. Like i said, under normal conditions (for sensor 1) it doesn't switch to sensor 2.

Removing the cats or changing the exhaust will not change what sensor 1 needs to do.

djamps

iTrader: (1)

Keep in mind under WOT (open loop) the ECU ignores all o2 sensor readings and fuels blindly off compensation and target maps.

Unfortunately the stock ECU, regardless of tune, cannot be set to ignore rear o2 function in closed loop. You would need a standalone ECU like Haltech for that.

Fortunately, I have zero A/F control issues (other than catalyst codes which I deleted) as long as the rear o2's are directly in the exhaust stream.