bump

 

I'm having the exact same problem as the op but with bank 2. Sometimes bank 1 code will pop up. My best guess is that it has to be an exhuast manifold leak most likely stemming from excessive vibrations on the exhuast from not having a cat brace installed on my HFC's. I have since removed my HFC's and replaced them with ART's and I still get the code. There were no signs of exhaust leaks on the cat gaskets. I really don't want to remove the manifolds. I've heard it's a PITA.

 

It definitely is a PITA, and I wouldn't recommend it except as a last resort. If that's what you think it is, take a close look around them and look for carbon residue or anything else that could be indicative of a leak. I'm looking forward to getting back home and tackling this thing, and I'd love to hear if you make any progress with this thing between now and then. Any help to point in the right direction would be huge.

 

Found my P2A00, or at least part of it.




Behavior:
- Clear fuel learning
- Drive ~50 highway miles
- P2A00 comes on
- Drive another 25 to 50 highway miles
- P0420 comes on

Logging with Cipher
- Just after clearing fuel learning, AFR on both banks look constant
- After driving on highway (closed loop condition), passenger bank will start to go rich
- Further inspection of logs show that the narrow band wasn't switching (stayed 0v) as frequent as driver side.
-- My Crazy Conclusion: In a closed loop condition, the ECU will continue to dump fuel into the cylinders to make narrow band emissions happy despite what the wide bands were reading. Since the passenger side narrow band was being fooled by the crack in the cat (which is located right next to the sensor), the passenger side bank went rich triggering P2A00. P0420 lit up because of the excessive fuel.

Fix
- Weld that bad boy up!

 

This is correct, the ECU does indeed make long term corrections based on the lower narrowband sensors. When I had a set of non foulers installed (to combat P04x0) I had the same issue with one or both banks wandering rich over time. I removed the non foulers and disabled P04x0 instead. Drives like a new car.

 

Hi Guys,
I have the same problem. Seen in closed loop running- idle or at cruise. One bank rich, one bank lean.
My car is a PNM35 Stagea. Just think of a wagon version of the G35x with different styling. It has a VQ35de.
My car was running fine, until recently when I installed a HKS single turbo kit. All four sensors are used in the kit- in the turbo dump pipe. What my car does is retain the 14.7 or thereabouts AFR, but achieves it by pulling fuel from one bank, and adding it to the other. I have Uprev tuner. I can only see the imbalance in the inj pulse widths- not the bank afrs, as the sensors read the same gass flow.
Again- I can clear learned fuel settings and it goes away, only to be learned and come back in 40kms. Car is currently running stock pump and injectors while I sort the issue.
I found if you disconnect one O2 sensor, it will force the car to run in open loop, and the car drives much nicer- but obviously I'd rather fix the problem.
So, I hope that my problem having all 4 sensors in the one gasflow will eliminate some thoughts such as exhaust leaks O2 sensor failures etc.
Anyone else had any sucess recently with this?

 

You will always see differing correction from bank to bank... mine is anywhere from 5-10% between banks at a given time. You say that the ECU is able to correct to 14.7 on both banks so I don't think you have a major issue other than maybe a vacuum leak closer to one bank.

The main topic of this thread is that the ECU makes *wrong* corrections causing the actual AFR to go too rich. This can be caused by issues like exhaust leaks, bad o2 sensors (antifoulers, wiring fault, ect), cam issues, clogged cat, the list goes on.

Either way, you can smoke test exhaust and intake to get a clue where the leak is.

 

Hi djamps,

First, thanks for the work you have been doing with uprev tuning- I have been reading for quite a while now, and enjoying the info.

To go through- There are nil vacuum leaks, there are nil exhaust leaks. The Cat is brand a new HKS unit.

What I am getting it seems is this-
My correction varies- agree, I have seen 5-10% and thats not a worry, that even happens on open loop. I have also seen it max out at 125- 75% bank to bank. As I have all 4 sensors in the one gasflow, they do not read the separate banks any more. The ECU is cycling each bank, looking for the slight increase in fuelling and trimming based on that. It doesn't see the difference in fuelling since the sensors are all in the one place. Therefore it increases the severity of the cycle until it either its maxed out, or it sees a differential.

Only way to stop it is unplug a O2, and run it in open loop.

Question- where do the US single turbo kits place the O2 sensors, and do they run in closed loop?

Another thing to ponder- Do your test pipes / HFC or whatever you guys run alter the position of the O2 sensor enough for the computer to receive different signals to what it expecting?

 

ok guys!! i think i have finally found out what the problem is, and why we cant fix it. ready..??
ok so first, this is all having to do with drivers side bank running too rich in closed loop.
+ car was throwing c/e lights for 02s, replaced a.l.l. o2's. didnt help.
called osiris-they threw some ideas, replace o2's and ecu.
+replaced ecu...nothing same problems..
called osiris-tried keeping it in open loop, no luck...
luckily we have a lead nissan tech at the shop and he did his thing and figured out the wiring circuit was bad

what the problem is, when the o2 wiring circuit goes bad. it fries the ground plugs in the ecu for the o2/o2 circuit

the fix:replace ecu, and fix all the wiring. after this is done the ecu is muuuch happier and will even out both banks.

setup
sts single turbo,deatschwerks 301 pump, w/ deatschwerk 600cc injectors, tuned with uprev.

 

Hmmmmm...

 

Winner winner chicken dinner?

 

That is an expensive fix.

 

ya, and a ******** reason for it failing. I'm glad they put quality wiring systems in this car.

 

Pretty much any shorted circuit will fry the ECU outputs...sucks but fact of life. Seen it happen often with bottomed out exhausts taking out o2 sensors... also an issue for vortech kits with the bank2 cam wiring getting weed-wacker'd by broken belts.

 

UPDATE:

So now that I'm finally back and have my car to work with, I decided to go back and re-test this part in a new way. After all, the possibility of the narrowbands causing the ECU to make corrections is something that I had ruled out in the past after doing research.

So yesterday, I went ahead and just unplugged the sensors from the harness, zip-tied the cables in place, and put some friendly duct tape over the connections. The hypothesis here being that if these are indeed the cause of the malfunction, then the problem and my ability to replicate the symptoms will disappear when I do this.

Sure enough, they did.

I have driven the car about 60 miles or so, doing everything I originally would to replicate the problem, but nothing. The car is running great, and the Cipher datalogging software is showing me that for all intents and purposes, the problem is gone.

Now it may seem premature to call it a game, given that it's only been 60 miles. But I can say with about 95% certainty, after all I did to replicate the issue, that it was the rear O2 sensors causing the problem. Thank God! Really. I'm thankful that not only is the issue solved, but that it's probably the cheapest solution available.

Where to go from here?
I wish I could just disable the codes I'm getting from having the narrowband sensors disconnected, I would. If someone knows how to do this with Cipher or by some other feasible method, please let me know. For the time-being, I'm going to leave it all unplugged until I can find a happy solution. Happier, I mean. I am happy.

 

^^ glad you got it sorted. You will need to use ROM editor to turn off codes, which requires a full uprev tuner license ($500+cable, or got to a pro-tuner for $300+labor) to load a new ROM with codes disabled.

 

onagao, do you have test pipes with non foulers? if so, just reweld the bung so the O2 is in the exhaust stream like djamps did. glad you finally figured this one out.

 

This is something that should work, correct, he does have ART pipes, so yes to anti-foulers, but the tune will need to disable the cat code.

However, onagao, i'm interested if unplugging the sensors caused the system to run in open loop?

 

Also, what would we say is now the easiest way to repro this condition. I'm also running ART pipes, if the anti-foulers are the root cause, then i'd like to confirm if i need to change anything.

Sorry, just read through the word doc, seems the best way is to go WOT when stationary and release the throttle immediately.

I'll try and give that a go soon and let everyone know.

 

Doesn't the ART pipes have built-in antifoulers? How would we go about with this issue then?

My car pre UpRev tuned didn't have any sensors/codes disabled. My mpg was fine.

After UpRev tuned + disabled sensors/codes or w/e, my mpg went horrible. Bank2 was fed more and more fuel.

Also disabling the code = it will never show up and throw a SES light? (emission purposes in TX)