Great, think I understand now. So, one side. P0174 at the beginning. You should swap left and right upper HO2S sensors only, do a hard reset (battery) and watch the trims evolve at idle. If it shifts banks, you have your problem. On MAF, did you happen to get the value at WOT?

As an aside, the upper HO2S sensor may not be as difficult as you think with the rental tool from OReilly/Autozone/Advance. Especially while you bask in the glow of swapping the engine...

 

My reader is telling me that the bank 2 number 2 sensor (downstream) is giving ZERO volts (photo above). The ECU seems to be trying to trim fuel but can't due to bad readings from the downstream sensor?

Should I be focusing on replacing the downstream sensor?

 

No..the downstream sensor has nothing to do with the ecu fuel trim adjustments, it is there to monitor the cats only.
You need to concentrate on the upstream sensors. S1 B1 and S1 B2 from your swap of sensor from B1 to B2 the indication is that you have a bad sensor 1 on bank 2.

 

I will, think I did already and the numbers on bank 1 went up to 19.5 and 25%... I guess I'll do it again for good measure after the reset.

So the voltage reading I'm seeing above has to do with the upstream sensors even tho they are labeled (obd label) as bank 2 sensor 2...? If so, in the mean time I guess I'll go ahead and buy sensor Denso 234-9016
​​​
Like the looks of this.​​​​​

 

I dont know why the voltage reading is showing 0v but it's not showing readings for your upstream sensor
Like i said, i dont use Torque Pro so dont know about setting it up to read the correct SAE PID's for the o2 sensors

I use obd Fusion and if you dont select the correct SAE PID's for the o2 sensors it will show 0v or no activity.

This is a Quote from an OBD forum...(it is disappointing that torque is not capable of detecting basic sae pids, try downloading and install the free torque scan, this may add more pis's to support reading 02 sensor 1) Un Quote...

You could try the obd fusion app about $5 from the apple store to read all the o2 sensors







The above photo is my obd fusion dashboard showing all o2 sensors,
as you can see the downstream S2 are shown in Volts and the upstream S1 are not
All car makes have an equivalency ratio for wideband sensors (upstream sensors) this helps make sense of the amps

The stoichiometric for upstream sensors is 1.00 and a working sensor will move up and down from this in small increments.

The stoichiometric for downstream sensors is 0.450 and a working sensor will move up and down from this in larger increments
any where from 0.100 to 0.900

If you could read the upstream sensors it would give more confidence before spending the big bucks on the upstream sensor.

 

In addition to XXR-Day's good advice, if the bank 2 trims went to zeroish while bank 1 went toward infinity after the upper connector swap, that's a good sign it's the bank 2 upper sensor as noted above. And it's good evidence that the sensor circuit for bank 2 to the ECM is fine. If so, there's some probability that it's a broken sensor wire given the circumstances. If you make the scanner work for the upper sensors, that's one bit of helpful information on the problem, also I'd examine the connector and as far down as I could on the sensor wire (hopefully to the sensor) and see if there is a break and if it can be fixed before using the new one.

 

Got ya both. I'm going out to give it a try...

Nutts and bolts, I'm good, but this kind of thing freezes my brain. Don't know why,,, just the way I'm made, I guess. Gotta get it figured out!

 

So I just came back and tried to read all that was posted but im sure I probably missed some things. Sitting in the car looking forward, bank 1 is on the right. Bank 2 on the left. Just saying this bc its a weird setup in my mind and I would’ve thought it was the opposite but it’s not. No the sensor that’s reading zero votes is bad. You should be reading an oscillating I’ll put going above and below zero like the other one. So you need to fix that first or else you’re never going to get into close loop mode with any sort of meaningful results.

just a warning I have to do the smoke test you can get some of that oil into cylinders which will mess up your plugs would you cause you to have misfires that should go away if you drive the car and burn that stuff off so don’t think about the misfires did you get right after you do a smoke test because you caused him but they shouldn’t be permanent.

The upstream O2 sensors are the ones that really are used to determine short term fuel trims they do work along side the downstream O2 sensors Soooooo you need to monitor all four. And the photos below is what you want to watch.

also important to remember is that with all 4 O2 sensors functioning correctly they are going to read the current state of affairs and start making adjustments to try to keep the mixture at an ideal air to fuel ratio so it will take some time for things to settle down. so don’t just look at them for 10 seconds and quit. you need to look at them for a good 20 minutes to an hour as they start making adjustments. they won’t fully complete making adjustments sometimes for days so sit there and watch these things and watch the direction that they start to move and that will give you a good indication as to whether or not it’s trying to get towards zero. But at no time do you want a constant zero. The voltages and currents should flip up and down above and below zero as shown in my photos


Signals from top to bottom:
O2 sensor 1, bank 1 (upstream) current
O2 sensor 1, bank 2 current
O2 sensor 2, bank 1 (downstream) voltage
O2 sensor 2, bank 2 voltage

O2 sensor 2, bank 1 voltage
O2 sensor 2, bank 2 voltage
Stft bank 1
Stft bank 2

 

Good Morning, Acuda - all!

Thank you. I also was under the assumption that the pairs of up and down stream sensors worked together (upstream being dominate played in trimming but not sole) to adjust fueling. As opposed to independently. Now I'm confused. I've been confused.

So, I just went out and did the hard reset. Swapped the up stream sensor plugs (only) and I think I noticed that the high positive values moved from the LH to the RH side. The car ran terribly. So much so that the check engine light started to flash which to ME says that things are OFF enough to damage the CATS at which I shut it off and called it quits. I had to shut it off before it fully warmed up due to flashing CEL.

Just to say - I drove the car last night. The running (not right of course) and it functioned in closed loop (not open) the entire drive. ECU trying to find balance.

My suspected wire damage (if there is any that came with engine swap) is to the downstream wires, not the upstream. The upstream weren't touched/squished buy the motor or trans case .

I also found monitor readings for bank 1 and 2 LT and ST fuel trims. Then, separate readings for voltages (similar to acudas) for the voltages at the bank 1 and 2 downstream (?) sensors... One, bank 1, seemed to be reading (OVER 1 VOLT) mostly, I think reading excess fuel, and the other was still stuck at zero. These, the downstream, sensor plugs were not moved today.

Yeah, I'm confused. I don't know what I'm seeing. Swapping plugs seems to add more troubles and skew info more than help.

​​​​​​Super interested in what folks think

 

I think the problem with ONLY swapping upstream sensors (leaving the downstream sensors) is that the ECU will see information that makes NO sense because the downstream sensors are reporting such different information... If the upstream sensor is reporting X, Y and Z value and the downstream sensor (which is plugged into it's appropriate CAT and side on the loom) is expecting A, B, and C, then I would imagine that the degree of contradictory information would drive the ECU nutts...

 

Yes agreed/confused..
Sorry if the plug swap has not helped in any way other than make things worse/confusing
Put all the plugs back to original and try to get your obd app to read all sensors upstream/downstream
Some cars do use the downstream sensor to help in a small way with fuel trim but im sure the early xk8 dont, i take it you have not had cat codes with this downstream sensor not working
Hopefully you can get the obd app to see the upstream soon..

 

So this tells you three things
1. Downstream left works when you have the 'potentially problematic sensor' assigned to the right.
2. Downstream right works when you have the problematic sensor on the left.
3. The problem is highly likely to be upstream left.

Note: You also know a fourth thing: Upstream right is okay from the original trims.

 

I would like to be as certain... Engine was running so badly, wasn't able to bring it up to operating temps and the ECU (I'm imagining) was confused - so I can't feel confident in any of the readings.

I've gone ahead and order the downstream sensor for the LH side as well. Fingers crossed. Hoping my new fangled O2 sensor tool will be all the rage... Rage - no pun intended...

Should help with the space between sensor and fire wall. Cheap money,,, too! We shall see...

 

Sounds like your removal technique with the twisting of the wiring, ended up tearing the wiring and now you are getting no O2 reliable connection. It’s a real pain to check continuity but I don’t believe you can avoid doing that

Z

 

My fear. That's if you're talking about wiring IN the loom? The harness, having been jostled and moved around in the engine swap, Ive been fearing that a covered/wrapped section of wiring has gone wrong, which will mean a terrible chase. Again, fingers crossed!

 

So, you know that probably did not happen in the harness since the harness remained the same, yet the swap of left to right changed the trim results. You've pretty much isolated it to something to the sensor connector to sensor side of the left upper sensor.

 

Wiring is funny. 5-6 months ago I removed the entire top end of my XJS. Fuel injection, coils, ignition, vac etc etc to do cam covers, fix oil leaks and replace gaskets - a refresh. Put everything back together and it ran like crap and I couldn't figure it out. Eventually I learned that I had harmed a connection in common with A and B coils, the ignition amps and the tach. No fun. Basically it was about disturbing a set of wires that was still in place, but just messing around with them built up what already had to be high resistance in a wiring job that PO had done,,, to point critical. One of the ignition amps was killed in the process, tach was going mental and ignition was all out of wack on 6 of the 12 cylinders... No fun. Found the "spot" where the wiring had gone south, resoldered and ran some new wire and BAM. Everything back to normal and exceeding what it was.

Like now, and I'm ashamed to say and I do have work to do, on 2 of my LH cylinders 1 of the 4 wires to the coil is cracking with wire exposed. Little bits of wire showing thru BUT that little bit is discolored and not a fresh clean copper. I just don't know where to get either new pigtails or all of the clips and such to reuse what I have. What I'm imagining is that further up in the loom there is another area of cracking or something that got disturbed when I pulled all of an the wiring away from the engine bay to pull and place the engine. Never know. It's been a worry since I did the swap..


This was it... All under wraps...

 

Yeah,,,,, something ain't right.
I hope like cuss that these O2 sensors will do the trick.

 

Just to mention that if the upstreams are wideband then they are current-sensed and you do not want to be looking at their voltage even if a tool reports it.

Also, that on many Jags of this sort of era the downstreams do take part in fuel trims but not a big part, as well as being used to check the cats for correct functioning.

If an upstream is not working (or say the wiring somehow was swapped) then expect major grief. Commonly you get one or more codes.

 

yes I believe the 2002 has the lambda sensors in the upstream and the later ones like mine are wideband.

I found this on the both the earlier and later cars (helps a little here maybe. Idk)

The following information taken from Jaguar and Denso technical papers applies to the Denso Lambda/Oxygen Sensors fitted to the X206 STR, I would therefore assume it applies to other Jaguar V petrol engines fitted with the same.

Overview:

Lambda Sensors work together with the vehicle’s fuel injection system, Catalytic Converter and the ECM (Engine Control Module) to help achieve the lowest possible output of environmentally harmful engine emissions:

The Lambda Sensor monitors the percentage of unburned oxygen present in the car’s exhaust gases.

According to whether the oxygen content in the exhaust gas is too high (a lean mixture) or too low (a rich mixture) the Lambda Sensor transmits a fast-changing, fluctuating voltage signal to the ECU.

The ECU responds to this information by adjusting the air/fuel mixture entering the Catalytic Converter. The goal is to keep the air/fuel ratio very close to the ‘stoichiometric’ point, which is the calculated ideal ratio of air to fuel entering the Catalytic Converter.

Theoretically at this ratio, all of the fuel will be burned using almost all of the oxygen in the air. The remaining oxygen must be exactly the right quantity for the Catalytic Converter to function efficiently.

One of the first Lambda/Oxygen Sensors introduced was the Zirconia Lambda Sensor which was placed upstream of the Catalytic Convertor.

Sometime later another Zirconia Lambda Sensor was placed down stream of the Catalytic Convertor to monitor that it was functioning correctly.

But due to the increasing stricter lower emissions outputs required of petrol engines the upstream Zirconia Lambda Sensor was replaced with the Wide Band Sensor.

The difference between Zirconia Lambda Sensors and Wide Band Sensors is that the latter is more sensitive and efficient than conventional Zirconia Lambda Sensors.

This is because of the way each type of Sensor measures the air/fuel ratio and the different output signals they produce to indicate the result.

Short Tech Info:

Wide Band Sensors indicate the exact air/fuel ratio value. This means that the engine ECM knows how far off the air/fuel ratio is from Lambda 1.00, and therefore also knows how much it needs to correct the fuel injection. This allows the engine ECM to correct the injected fuel quantity to achieve, and maintain Lambda 1.00 almost immediately. It outputs a small current between -10mA and +10mA, where the output is a stable value proportional to the air/fuel ratio.

With a Wide Band Sensor, the engine ECM will notice fractional changes in air/fuel ratio even in changing conditions. The ECM is therefore able to make precise adjustments, considerably reducing any under or overshoot in fuel. This results in optimal gas conversion inside the Catalytic Converter resulting in cleaner air, lower fuel consumption and better driveability.

Zirconia Sensors indicate whether the air/fuel ratio is either above or below Lambda 1.00. The engine ECM alters the fuel quantity step by step until the Sensor indicates that the mixture is wrong again. At this point the ECM starts correcting again, step by step in the other direction. This method results in a relatively slow and constant ongoing correction around Lambda 1.00, never able to exactly maintain Lambda 1.00. A Zirconia Sensor outputs a small voltage between 0V and approx. 0.8V, switching from low to high at around Lambda 1.00.

Overall especially in changing conditions (sudden accelerations or decelerations) systems with a Zirconia Sensor will have an under or overshoot in fuel resulting in a less efficient Catalytic Converter.

Long Tech Info:

Wideband heated oxygen sensors(Upstream O2 sensors or O2 Sensor 1) are located before the catalytic converters and are commonly called Wide Range or Linear sensors. These sensors expand on the principle of the Zirconium Dioxide sensor by incorporating a second chamber the ‘Pump Cell’. With the addition of the Pump Cell the sensor is actually two sensors in one. The cells and heating element are housed within ceramic layers comprising a Diffusion gap, Sense Cell, and an Air Reference Chamber.

The purpose of the Pump Cell is to counteract the change in voltage of the Sense Cell and keep it at 450 mV. The Pump Cell is in contact with the exhaust stream; at vehicle start up the Sense Cell will read 0V and the Pump Cell will read 0 micro Amps. As the exhaust oxygen content decreases, oxygen ions will begin to decrease in the exhaust stream and the voltage on the Sense Cell will begin to increase.

The ECM responds by providing a negative current flow to the Pump Cell, which reverses the flow of oxygen ions and limits the voltage rise on the Sense Cell. As O2 ions begin to flow away from the Sense Cell, the voltage begins to decrease and the ECM responds with a positive current to the pump cell by reversing polarity, which moves the oxygen ions back towards the Sense Cell bringing the Sense Cell voltage back up to 450mV.

The ECM monitors the current changes to the Pump Cell and will adjust the air/fuel ratio at the same rate; this adjustment is known as fuel trim’

Expected current readings from the Pump Cell will cycle above and below 0 Amps, with expected maximum readings of +2mA to -2mA. If there is zero current flow on Sensor 2, the air/fuel ratio is at equilibrium (14.7 to 1 stoichiometric), referred to as LAMBDA 1 or Oxygen Sensor Equivalence Ratio 1.

Wide range O2 sensors require a temperature of approximately 750° C to operate properly. They are fitted with internal heaters to decrease warm-up time and maintain sensor temperature. The heaters are controlled by the ECM with a modulated ground signal.

Zirconium Dioxide Heated Oxygen Sensors(Downstream O2 sensor or O2 Sensor 2) are constructed with 2 platinum electrodes with a zirconium dioxide element between them. The ceramic sensing element acts as a miniature catalyst to support reactions in the incoming exhaust gases.

Before engine start up, the oxygen content surrounding the exterior of the downstream O2 sensor and in the exhaust pipe is approximately 21%. When the engine is started, exhaust gas will begin to displace the oxygen in the exhaust stream.

The difference in oxygen content causes a catalytic reaction to occur between the platinum surfaces and the zirconium dioxide, which will result in oxygen ions flowing toward the exhaust stream. This oxygen ion flow produces current, which causes a rising voltage to be transmitted to the ECM.

The ECM compares the O2 sensor signal to a fixed 0.450V reference voltage. When the signal voltage rises above 0.450V, the exhaust oxygen level is considered low (rich); when the signal voltage falls below 0.450V, the exhaust oxygen level is considered high (lean).

Because an O2 sensor will not produce voltage until the sensor temperature approaches 316°C internal heaters are used to decrease warm-up time and maintain sensor temperature. The heaters are controlled by the ECM with a modulated ground signal.