Luxor

iTrader: (15)

I am trying to figure out why both of my banks fighting each and running rich/lean opposite of each other. Can someone please take a look at my pictures and tell me what the snap shots mean and what could be causing this?

Also whats the difference between "SHRTFT1" and SHRTFTB1S1"?

One picture is at idle and the other is holding the throttle at a steady 2K RPM.

Specs:
-Stock 2JZGE engine with NA-T 70mm turbo
- AEM FIC 6 wired with plug and play Boomslang harness (already tuned by professional tuner)
-550cc injectors and Supra TT fuel pump
-all o2 sensors connected to downpipe (I have 02 sensor spacers on both (post cat) sensors)

Ali SC3

iTrader: (10)

I want to say your car came with 3 or 4 o2 sensors. one was bank 1 sensor 1 for 3 cylinders, another was bank 2 sensor 1 for the other 3 cylinders, both of these are pre-cat. the third o2 or 3rd and 4th on some cars are post cat for seeing if the catalyst is working, these would be "bank 1 sensor 2" and "bank 2 sensor 2" depending on how many the car came with.

basically in a nutshell, I think you spaced out the wrong 2 o2 sensors. so to say bank 2 is the post cat one would be incorrect, and if you put a spacer on this one that could make sense why its trying to add fuel on bank 2 when its trying to pull fuel on bank 1. space out the correct ones and it should all work again. its easy to mix up especially if you didn't mark them before removing the stock exhaust manifold, they are all right next to each other. thats what I think anyways, you need to have both bank 1 sensor 1 and bank 2 sensor 1 like right next to each other on the downpipe, with no spacers whatseoever.

you were sort of saying bank 1 is used for fueling adjustment, and bank 2 is used for checking if the cat is working (so you spaced them).
In fact the toyota numbering bank 1 sensor 1 and bank 2 sensor 1 are used for fueling adjustment, and bank 1 sensor 2 and bank 2 sensor 2 are used for checking if the cat is working.

so you can see how spacing out bank 2 sensor 1 was a bad idea, cause its used by the ecu for fueling the car.

the third/fourth o2 should be in the factory position under the car post cat or on the midpipe with a spacer if you have no cat. again the third o2 sensor is not the one you are seeing up there because there is no fuel trim from the third o2 sensor and the scanner does not show that on the same page If your car had 4, then the same thing is true for number 4 and they are each probably just right after each of the cats (if there was 3 it would be further down where they merge together). The sticker on the hood will say how many it came with originally.

so right now from what I am reading the ecu is taking fuel away from 3 of the cylinders, and dumping fuel into the other 3 cylinders, which would make it run badly and likely misfire.
once this starts happening it probably even further gets thrown off cause the sensors are now reading the chaotic fueling that is coming out of the the motor now and making even further wrong adjustments so all 6 cylinders would be off instead of just 3 after a few seconds of feedback.

the difference between "SHRTFT1" and SHRTFTB1S1" is that the first one is an average of all the sensors on bank 1 and the second one is telling you what sensor 1 on bank 1 is reading. it just so happens on the way the inline six is setup where 3 cylinders is a "bank", that there is only 1 sensor on each bank that affects the fuel trim. the second sensor on each bank is only for checking catalyst efficiency.

I don't know why toyota decided there were 2 banks on the same side of an inline 6 engine, and that sensor 2 on each bank is the catalyst sensor, but it was probably some sort of precedent from the earlier inline motors. I am going off memory here so if I am a little off then yeah, but I think i am pretty close.

this picture of an obd2 ggs300 stock echaust should make it clearer.
notice the one after the cat is labeled bank 1 sensor 2. this is the one you should space out.
the one above that is not circled is bank 1 sensor 1, and is the one that does the fuel trims.
the other exhaust runner will have the exact same setup of 2 sensors on it but will be called "bank 2"
so the top pre-cat ones should have stayed in the downpipe, and the bottom post cat ones should be spaced out at the least if not extended to the midpipe and then spaced out.


Also to note with the FIC, i think it can simulate values for the post cat o2 sensors if you have issues with the spacing out not doing the trick.

the earlier SC's did not have as many cats or post o2 sensors, but they still had 1 pre-cat sensor for each set of 3 runners, i think this one shown below is a 92, the cars that had the older exhaust like this but still had to have the catalyst check would have 1 third post cat o2 sensor on the midpipe.

Luxor

iTrader: (15)

Thank you very much for very detailed and informative post. The SHRTFT1 vs SHRTFTB1S1 made sense to me and now I know which one to monitor for live direct data of my primary sensors.

I think you misunderstood the part about which sensors have the spacers on them. I meant to say that I have both post-cat sensors spaced out (B1S2 and B2S2) which is why it confuses me that both banks of fighting each other. I have already replaced my B1S1 sensor with a new OEM sensor thinking it was a bad sensor but that didn't fix my problem.

Also, I did an experiment...I disconnected my B1S1 and B2S1 and even though the all the STFT were reading 0, the LTFT were both reading opposite values when I revved my engine to 2K RPM. The LTFT for bank 1 was at -32% while the LTFT for bank 2 was at a positive 22%.

Does this mean that I may not have a O2 sensor problem since I bypassed (disconnected) them?

Ali SC3

iTrader: (10)

thought I had found it that would have been an easy fix. still double check you didn't mix up any of the 4 connectors.

long term fuel trims do not change frequently and are stored in the computer until it is reset completely by a scanner or pulling the battery for a while, meaning even though you disconnect the o2 sensors that only affects the current short term trim and the computer will still use its old values for the long term trim (cause to set the long term trim the ecu has to observe the short term trim average in a certain direction for a certain amount of time), hence why they did the long term fuel trim if you have an o2 that suddenly goes bad the computer isn't way off due to the long term fuel trim stored. but that is also why people with bad o2 sensors can get by until their ecu is reset sometimes, its hard to tell anything is wrong cause of the old long term trim from before it went bad, but after its reset to zero people tend to notice a bad sensor then cause the short term will be wrong and there will be no long term trim to help the ecu guess. obd1 only had 1 trim I think, the short term and long term are obd2 fancy stuff.

if you reset the ecu completely, or clear it with a scanner, and try it with the o2's disconnected it shuld have zero in there and the car should actually start running fine again.

If its hooked up right and its doing that, I would say most likely that one or both of the main 2 o2 sensors are bad, or the signal wire is broken or pinched or grounding out somewhere. you said you replaced b1s1 but according to the data that one looks ok its the b2s1 that looks fishy to me, good chance its lazy and failed in the low voltage position which says lean and confuses the ecu into a positive trim. most of the time the car runs rich and has a negative trim, so that stands out to me with the info you have given.

that is assuming though you don't have a mechanical problem like a faulty injector on that bank delivering less fuel, or some ignition component causing a misfire that would allow the o2 on that bank to read lean all the time. I would try and zero the long term fuel trims and see where you are after that at this point, and possibly replace that second main o2 sensor.