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O2 sensor reading on Bank 1 vs Bank 2

44K views 356 replies 27 participants last post by  Final GTS 
#1 ·
I'm going through the process of having my car tuned via SCT, and now 12 tunes into the process we are at gridlock with a sensor reading issue. Basically, the driver side bank reads way differently than the passenger side, and the verdict that it's Bank 1 that's the anomaly is, fuel table values match the sensor on Bank 2, but not Bank 1.

* 2001, 5# Roe, factory heads/cam.

* Belanger headers, RT ceramic cats, Dynomax 3" bullets, side exhaust.

* O2 sensors are factory Bosch ~ 2 years old with 5K miles, installed in the single tube spot that Belanger headers come with.

* Years ago when I put the headers on I started throwing P0135 (Bank 1 preheat) all the time. Whether the sensors are in the single tube like Belanger made them, or in the bung I added to the merge collector. Code P0135. For whatever that may mean.

* Plugs are a few months old with ~ 2k miles.

* Wires are AB's ~ 5 years old w/ 14K miles.

* Coils are factory original w/ ~ 53K miles.

* Exhaust - manifold to head: no audible leaks or visible carbon tracing i.e. signs of a leak.

I list all of those things as they have been brought up to be suspect in this O2 sensor imbalance. I can't look at any particular one as "the one," or one that is more suspect than the other.

So, in ignorance of it all, my only plan would be to replace it all. Plugs, wires, sensors, coils and so on, without knowing for sure if that will even fix it.

Any suggestions or similar experiences?

Short of tuning fuel enrichment on acceleration as well as higher throttle inputs approaching WOT, the car actually does run pretty well. Those lacking areas have simply not been given any attention yet in the tuning process.

This last log that I did shows the difference between the 2 banks. You can see the disparity clears up as the rpms increase.

 
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#52 ·
Got it...just as you said...your relay shouldn't be affecting anything. So now your back to verifying that the resistance between each leg of both o2 circuits match. Looking at the diagram...I would Ohm out leg 30 of the ASD relay to the dark green / orange feed wire at the harness connector of each sensor. They should match. Measure resistance again with the system powered and make sure the resistance matches.
 
#53 ·
Yes, I do plan on checking the resistance of each wire to each connector. Probably do it both before replacement of the connectors, and then again after. Just to be thorough and drink beers :cheers:
 
#54 ·
....if the resistance checks are good on the feeds energized and not energized then I would measure resistance between the black and light blue wire from harness connector to harness connector (shared sensor ground. Should hover at 0 ohms energized or not.) If that checks out then I would bet a bucket of beers that the issue lies within the k241 circuit. It runs from Pin 24 of the C1 connector to the light green / red wire of the bank 1 o2. The resistance of the k241 circuit should match the resistance of the k41 circuit which runs from pin 26 of the C1 connector to the black / dark green wire of the bank 2 o2 sensor.
 
#55 ·
I want to thank everyone that has donated blood recently at their local collection point. Not sure how many pints I lost yesterday during 6 annoying hours of undoing the sensor wire relocation from 2008, but during the process of figuring out my air intake from the front bumper to the throttle bodies needed to come off, then the power steering cooler, my custom header heat shields, both hoses from the AC compressor removed, all to get the fucking wire harness to the point I could work on it, I did not have a fun day. Short of the fact it's now undone and done right during the undoing.

Soooooo, if anyone was to approach me now about moving my sensors again, or anything else oxygen sensor related, I'd probably mumble something that if played backward at 33-1/3 rpm, would resemble, kiss my ass!




I checked all the wiring from the connectors back to car, both with the old connectors and new ones. All were fine. About 0.3 ohms or so, which is what all three of my DVM's read when you touch the leads together.

* Heater circuit B+ was checked back to the ASD relay itself. Pulled the relay and probed the pin socket in the PDC.

* Heater circuit ground was checked to the main chassis ground under the PCM.

* Sensor ground checked back to the PDC. Pulled the connector and probed the socket.

* Sensor signal; ditto as the ground.




I put back in the Bosch sensors I'd been using to log with since I started the tuning, and went for a drive.






Then I put the new OEM NTK sensors in and went for a drive.

An interesting note that I made when I was changing the sensors. I let the car sit for about 20 minutes or so after the first drive with a fan blowing at the front. When I pulled the passenger side sensor, with leather work gloves on, it was still so hot I could only back it out one turn at a time before I had to take my hand off of it because of the heat. The driver side I twisted all the way out at once without burning my hand.

Why some 20 minutes later was the Bank 2 sensor still so hot? Hmm.

Anywho, the data below, is now how and where the sensors are going to stay. And there is obviously still a disparity bank to bank. Does anyone know what the difference between those bank values actual means? Like, it may be (15) bank 1, (-10) bank 2, but from a trim amount, what does that mean?







Short of comments or advise from any and all, my plan from here is to pull plugs on the cylinders with the sensors, and maybe a few to each side. And check header to head fasteners for tightness.





Also, at some point as a list of things to check gets worked off, is the potential of realization that this may just be the way it is, i.e. there is nothing to fix, as, um... it's just the way it is with my sensors. Not there yet on that thought, but the damn car sure does run good seeing as we're still just tinkering with basic fuel trims.
 
#56 ·
I want to thank everyone that has donated blood recently at their local collection point. Not sure how many pints I lost yesterday....Soooooo, if anyone was to approach me now about moving my sensors again, or anything else oxygen sensor related, I'd probably mumble something that if played backward at 33-1/3 rpm, would resemble, kiss my ass!...

:lol:
So now is a bad time to talk about power-steering cooler! :D
 
#60 ·
Dave,

I'm not an expert yet with the viper but here are a few things that work.

Go for a good ride in the car get everything up to normal operating temperature, then get someone to hold the car at about 2000 rpm.

Using an IR gun check the temperature of each header primary a couple inches from the head. write the temps down.

Then try again at 3500 rpm.

Just saying you might find something interesting... there should be very little temperature difference.
-----------------------------------

Might want to poke around with an IR gun a few different places on the car compare the sides, etc.
______________________________________

Second thing I was thinking about is its fuel related.

If you havn't done so pull your manifold and fuel injectors maybe one bank is starving b/c of crap in a fuel rail?

---------------------------------------------

No pinched or broken vacuum lines or something stupid right...
You can use ether or carb cleaner, or WD-40, to find those.

Hopefully something above helps.
 
#61 · (Edited)
The above post(s) are actually a few good ideas to try and confirm that what the sensor is seeing is real, and not induced by the sensor itself, or being caused by an actual cylinder issue.

Getting everything back together and tested, while not as fruitful as I would have liked, has still gone a long way towards crossing items off the list of potential issues here.

I see the following items as remaining things to test:

1. Confirm that one side of the engine is indeed "running differently" than the other.
1a. I can supply a tune which turns the trims off totally, and then using an IR gun without any interference from a "chicken or egg" scenario is possible. This would also make easy identification of a major fueling or ignition problem by individual cylinder. Granted, it cannot determine the cause, but at least could isolate a bank and/or cylinder issue.
1b. Performing a leakdown/compression test would show any major structural/condition differences between the cylinders. Not always conclusive, but enough to help us here in a big way.

2. Confirm that the PCM is actually controlling the heater correctly.

3. Confirm that you have normal fuel, spark on the affected cylinder, and normal plug condition.


To boil it down, if you had a bank to bank difference that was steady at ~10%, I could live with that. However, the simple fact that when sitting at idle, that trim seems to "run away" is very, very suspect. Something is causing trouble with sensor heat or is causing a misfire at low loads.

Dave6666 said:
Anywho, the data below, is now how and where the sensors are going to stay. And there is obviously still a disparity bank to bank. Does anyone know what the difference between those bank values actual means? Like, it may be (15) bank 1, (-10) bank 2, but from a trim amount, what does that mean?
The value is simple, it is percentage of fuel added or removed from base.
 
#62 ·
Getting everything back together and tested, while not as fruitful as I would have liked, has still gone a long way towards crossing items off the list of potential issues here.
Seeing as Step 1 was to test the wiring (by a simple ohm meter test), then replace the wiring with new and retest (by a simple ohm meter test), followed by repeating a previous log file (re-logging the old sensors with the new wires), followed by installing the new sensors and testing them (logging), what fruits did I miss in all of that?
 
#66 ·
I'm going to pull my passenger side heat shield off (which was not part of the wiring process and 3 pints of blood lost; just the driver side), at which point getting the IR on the tubes as well as pulling plugs for a reading, will propagate itself into more fun. With hopefully no more bio transfusions to the surrounding work areas.

I really did have to take the garden hose to the driver side heat shield after I finally removed it, to clean the blood off of it.
 
#68 ·
*Plug Readings*

Driver side. Plug to far left is front of engine, next one - second from left - has sensor. did not pull plug all the way toward back of engine.

X - SENSOR PLUG - X - X - DID NOT PULL



Rolled over, same order.



Closeup of sensor plug; in the middle.



Passenger side.

DID NOT PULL - X - X - SENSOR PLUG - X



Rolled over, same order.



Closeup of sensor plug; in the middle.







Short of additional opinions... they all look the same, like the plugs in the sensor cylinders look the same, left bank to right bank. If that cylinder in the driver side bank had any problem up stream of the head to exhaust manifold connection (header), how could it be that the plug reads just like the others?
 
#76 ·
*Plug Readings*

Driver side. Plug to far left is front of engine, next one - second from left - has sensor. did not pull plug all the way toward back of engine.
Maybe I missed it, but I would pull the rear plug to verify it's not fouled out. You probably know this but the two rear plugs on each side of a Roe S/C engine run richer due to the manifold design.
 
#79 · (Edited)
After I saw that plug I thought about pulling the next one, but as Dan already pointed out, it is not related to solving this. I'm sure before it's all over they will be inspected.

Based on what I see on those plugs, there is nothing out of the ordinary there. However, I will say that gapping appears questionable on some, I would certainly re-check they are all @ .035
I rechecked all the ones that were out. #2 was slightly open past 0.035.

I'm sure you're aware that because they weld that damn electrode on "tall," that by the time you bend it down to the desired gap it's well past 90*, and the actual measured gap is at one side of the center electrode, matching the end of the angled bent electrode.

I would also NOT strike off a crossed plug wire or crossed injector driver. As long as the firing order is rather close, most people wouldn't notice such. Its always worth a quick trace to make sure they are correct. Just because an issue was not noticed before, does not mean it was never there.
The injector connectors are very difficult to access for the most part, but with some needlenose to pull and a screwdriver to pop the latch, I got the one off of #3. I ohmed the driver wire out to the PCM connector; all is good. I did not check the ASD 12V+ as that is common bussed in the harness to all of the injectors right?

Plug wire #3 was traced to the correct location on the coil pack. I did not pull the cowl so access to any others was limited.

No, the IR test should be at a hot steady idle...
That is a much easier task at that RPM and I will do that in the next day or so.

Regarding the injectors; The issue here is not so much crossed wires, as much as it is a potentially lazy injector driver. Swap the injector driver from Cyl. 3 and 4 [even temporary is just fine] and run the engine, see if the error jumps to the other side of the engine. An out of time injector will not cause much running change once it stabilizes due to transient fuel balancing out anyway. The only fuel issue this will not locate is a potentially lazy/sticky injector.
If I am following you correctly here, I will need to jump the harness from the passenger side to the driver side and visa versa. The harness will not reach, so I will need to get extenders made. Can you do that? Also, I cannot access the #4 injector connector w/o pulling the fuel system on that side. PITA...

To check and make sure all injectors are properly pinned, you can check that simply by unplugging one at a time until CEL pops a code. The code will tell you which injector the ECU thinks it is. Or, you can just apply voltage to the ASD, and ground each ECU connector pin for the injector and feel for a "click". [after running with fuel pump relay pulled of course as not to flood] If these are out of order, it would definitely be a factory mistake. The injector wire length really does not allow for that kind of mistake... but pinning from day1 could. Tracing the wire color also works. I have actually seen this once before.
Pretty sure I covered the suspect cylinder with my driver continuity check @ #3. Is there value in pulling my fuel system off to gain access to all the others to check them too? PITA...




Also of interesting note ref. I made the comment about the O2 sensor being so much hotter on the passenger side. Remember when I said my extended sensor harness wires that ran along the frame rail to the collectors (before I shortened them back to stock length / location), that the loom on the passenger side melted, but the driver side where the sensor was cooler, the wire loom did not melt? Same distance from the header in each case, and the loom was fastened in the same spot on the frame rail on each side.

Melted side, one more time...



Anywho, that happened 6 years ago. So this heat disparity, whatever it is, for whatever it means, is a 30,000 mile old problem more than likely.

Hmm. I wonder if it's my heat shields lol. They are pretty functional.
 
#72 ·
As we are in the early development of tuning i.e. base fuel maps, I would venture to guess timing is just at a basic setting and has not been optimized yet. This is also the first time I've pulled the plugs, so Dan has not seen them either. Anywho, back to timing, Dan can comment on if that is a later down the road aspect of how he tunes.

Regarding logging, my laptop with PCMScan software is also real time per the OBD port. I would assume that the frequency of yours is likely the same as mine, which is highly limited by the OBD itself to maybe 10hz or so. But yeah, shag your ass up to Fort Worth and lets go log :D
 
#73 ·
Based on what I see on those plugs, there is nothing out of the ordinary there. However, I will say that gapping appears questionable on some, I would certainly re-check they are all @ .035

Regarding timing, everyone needs to remember this car is only tuning base tables right now, there has been virtually no heavy loading at this point, and certainly no WOT. The plugs are also rather new, they arent going to show any long term easy to read bands.

I would also NOT strike off a crossed plug wire or crossed injector driver. As long as the firing order is rather close, most people wouldn't notice such. Its always worth a quick trace to make sure they are correct. Just because an issue was not noticed before, does not mean it was never there.
 
#74 ·
OK. Per our email communication I will do the IR test on the primary tubes at 2K & 3.5K rpms. The neighbors will just have to KMA lol. But how long do I need to hold at said rpm before starting to take measurements? Based on videos I've seen of headers glowing on the dyno, give it 10 to 15 seconds?

I'll trace the plug wires out, but they are the way they came from the factory. I have replaced them more than once, but each time was one wire at a time fully placing it in the holders etc before moving on. So any mistake there originates back to the order CAAP built the car to.

Regarding the injector sequence, not sure how that would be possible to get out of order. At least without further explanation. The chassis side harness connectors are of course from the factory as installed on the car to feed the injector harness, and my injector harness is the one you modified for me to fit the ID1000 injectors. The individual injector wires as they branch out of the harness you supplied go in that order up and down the cylinder bank. So once again, from the injector harness back is CAPP factory original, and the injector harness itself is Dan / VSP. Please further explain how I need to troubleshoot this, or what the potential problem areas could be.
 
#75 · (Edited)
No, the IR test should be at a hot steady idle while the "issue" is actually occurring. We know that everything stabilizes at the upper RPM's anyway. we are looking for confirmation that the sensor is seeing a real problem, and then trying to isolate that problem. A "trims off" file in open loop will cause all injectors to fire at the same PW, and effectively "ignore" the sensor. If the temps are balanced, the sensor is suspect. If the temps are way off, then it confirms the sensor is indeed seeing a real problem starting upstream somewhere.

Ignition Wires/Spark: Check to make sure all wires are on proper coil points. Check spark with a spare spark plug while car is idling [disconnect injector] and compare spark energy between cylinders, or look for missing sparks, etc.

Regarding the injectors; The issue here is not so much crossed wires, as much as it is a potentially lazy injector driver. Swap the injector driver from Cyl. 3 and 4 [even temporary is just fine] and run the engine, see if the error jumps to the other side of the engine. An out of time injector will not cause much running change once it stabilizes due to transient fuel balancing out anyway. The only fuel issue this will not locate is a potentially lazy/sticky injector.

To check and make sure all injectors are properly pinned, you can check that simply by unplugging one at a time until CEL pops a code. The code will tell you which injector the ECU thinks it is. Or, you can just apply voltage to the ASD, and ground each ECU connector pin for the injector and feel for a "click". [after running with fuel pump relay pulled of course as not to flood] If these are out of order, it would definitely be a factory mistake. The injector wire length really does not allow for that kind of mistake... but pinning from day1 could. Tracing the wire color also works. I have actually seen this once before.
 
#81 ·
Obviously its a bad PCM.
It's on the list. Really. I made a list :)

As this goes on, I thought it would be useful to capture all the ideas. And as all brainstorming sessions go, there are no bad ideas, so I went back through this thread sand got them all. There may still be some from me and Dan's emails missing, but this covers this thread so far.

DONE (in chronological order)

Swapped old Bosch sensors from side to side and relogged.
Checked sensor wires before replacing connectors.
Replaced sensor connectors and shortened wires back closer to factory length.
Verified sensor heater controls are wired to upstream sensors.
Checked O2 sensor ground wire at AC compressor.
Checked sensor wires after replacing connectors.
Relogged old Bosch sensors after connector replacement.
Installed new OEM NTK sensors and logged.
Pulled plugs 1 thru 8 to inspect and confirmed gaps @ 0.035 while they were out.
Checked #3 injector driver wire back to PCM.
Checked #3 plug wire back to coil pack.
Checked #3 header bolts at head for tightness.

NOT DONE YET

EXHAUST
Look for exhaust leaks at collector area by disassembly.
Replace header gaskets at head / inspect.
Check all header bolts.

ELECTRICAL / WIRING
Trace all injector driver wires.
Swap O2 sensor harnesses side-side.
Swap the bank 1 and bank 2 sensor heater controls.

IGNITION
Spark check cyl #3 with extra spark plug.
Trace all spark plug wires.
Replace spark plug wires.
Replace coil pack(s).
Look for little balls of metal on the plug electrodes.

TUNING
Replace PCM.
Tune with a wideband.
Log O2 sensor voltage via PCMScan.
Use Megasquirt.
Confirm that the PCM is controlling the sensor heaters correctly.
Install wideband and compare against factory sensor.

OTHER
Leak down test.
Compression test.
Shoot headers with IR at hot idle.
Shoot headers with IR at hot 2K & 3.5K rpms.
Pull fuel system apart to look for crap in it.
Confirm normal spark and fuel on cyl #3.
 
#83 ·
Put the plugs back in, swapping #'s 3 & 4 side to side, took a little drive to log that, and shot the headers and sensors with the IR.

First the temp measurements. The reading jumped around quite a bit so it was a bit of a judgement call what the number was. It may have been the reflectivity of the header coating. Dunno. Here's the data.

1) 590 2) 520
3) 740 4) 680 <- sensors
5) 750 6) 710
7) 670 8) 670
9) 540 10) 680

Sensor) 270 Sensor) 310

I shot the tubes from a few inches away about mid tube bend @ the port. I shot the sensors right off the wrench hex.

Regarding heat in the area of the sensors, especially with my heat shields on, the driver side sensor on the Belangers has more room around it. The passenger side is more compact in the cluster of tubes. My driver side heat shield does not blind, or hide the header tubes as much as the passenger side does; it hugs the tubes well.

Anywho, I'm thinking of wrapping the sensors with header wrap for a test, and maybe a with and without my heat shields test. That still just bugs me how those wires tried to melt 6 years ago on the passenger side.

Driver side sensor viewed from above:



Passenger side:



I also swapped plugs 3 & 4 as I installed them and went for a neighborhood drive. No highway so the log has less activity up the rpms.

The previous run with before switching the plugs (which included hiway):



Then swapped plugs 3 & 4. Think it might be another good test to put in a set of factory SRT Champions instead of the dual heat range NGK's?

 
#159 ·
Plugs 3 & 4 were swapped a while back. Scroll down.

Put the plugs back in, swapping #'s 3 & 4 side to side, took a little drive to log that, and shot the headers and sensors with the IR.

First the temp measurements. The reading jumped around quite a bit so it was a bit of a judgement call what the number was. It may have been the reflectivity of the header coating. Dunno. Here's the data.

1) 590 2) 520
3) 740 4) 680 <- sensors
5) 750 6) 710
7) 670 8) 670
9) 540 10) 680

Sensor) 270 Sensor) 310

I shot the tubes from a few inches away about mid tube bend @ the port. I shot the sensors right off the wrench hex.

Regarding heat in the area of the sensors, especially with my heat shields on, the driver side sensor on the Belangers has more room around it. The passenger side is more compact in the cluster of tubes. My driver side heat shield does not blind, or hide the header tubes as much as the passenger side does; it hugs the tubes well.

Anywho, I'm thinking of wrapping the sensors with header wrap for a test, and maybe a with and without my heat shields test. That still just bugs me how those wires tried to melt 6 years ago on the passenger side.

Driver side sensor viewed from above:



Passenger side:



I also swapped plugs 3 & 4 as I installed them and went for a neighborhood drive. No highway so the log has less activity up the rpms.

The previous run with before switching the plugs (which included hiway):



Then swapped plugs 3 & 4. Think it might be another good test to put in a set of factory SRT Champions instead of the dual heat range NGK's?

 
#84 ·
Hey Dave,

Can you check the following:

1. Let the car sit and idle when hot, and just keep on idling. Can you confirm that once the STFT hits around 20%, is stays there? Or does it keep creeping all the way to 33%?

2. I will send you a Trims Off file, and repeat the IR check with the fueling balanced at the injector with no feedback loop.

It looks like misfire is out, but now we need to determine why it *actually* is demanding higher fuel PW. Lazy Injector or driver, or O2 heater seem to make a bit more sense here.
 
#85 ·
OK. Send me the Trims Off file. I will also need to know if I am to drive around with the Trims Off file to heat up the car and then shoot the IR, or drive around with my normal tune file (#12 is being used for all of this), and then stop and load the Trims Off file simply to do the IR test.

I do see the idle cell creep when I have been logging and then stop the car at a light or whatever. It is obviously populating and averaging that idle cell with various values throughout the drive, with a differing value at extended idle. Which could be creep or not.

I will take a romp tonight to heat the car up and then pull to a stop and start monitoring the idle cell to see if it creeps. That will eliminate any data in that cell from normal driving.
 
#86 · (Edited)
Sent.

Warm everything up, drive, etc, then kill and load the T. O. file. Start up, and wait for it to stabilize after a few minutes, and see where she stands.

[Separate Test] Rather than checking the Table [which averages], check the Data View instead. That will give you a real-time display of the PID, not an averaged one.
 
#87 ·
I love these threads, everyone learns.

I'd also like to follow up with stating you are in awesome hands with Dan (you obv know this or you'd be somewhere else). He did the SCT tune on my GTS remotely and his given his time very selflessly to me on numerous occasions. It hasn't and won't be forgotten.

Enough nutswinging and on with the progress, I'm excited to see the outcome here.
 
#88 ·
Fronts 1&2 are probably a little colder b/c the fan was running or more airflow etc.

What I was really looking for was a colder or warmer plug in the middle. What your results sort of weight out is an exhaust leak and miss fire rich condition on 3-10, with the exception of 9. (then again 9 might have better air flow)

9 could be colder or a richer exhaust which is sort of seen in the sensor (maybe...).

Its not enough temperature difference to say anything with certainty.
Might want to try again at higher RPM and see if the temp diff between 7 and 9 increase. (injector leaking by or whatever reason)
 
#89 ·
Higher RPM is going to stabilize the temps and severely skew the results we are looking for. This is a problem that is specific is lower loads and lower RPM. The test was also done with active trims, which means a "problem area" may be overruled by the adaptive trims, and is effectively being hidden.
 
#90 ·
Higher revs on a sticking injector or bad spark will stabilize exhaust temps?

I understand adaptive trim but he is not trimming per primary correct its per bank.

So if with higher compression and RPM the combustion chamber pressure increases and the spark may fail more often. Then allow more unburnt gas through the primary cooling the mix in the primary but making the exhaust richer. Then adaptive trim should reduce the fuel to this bank and all primarys.
This would make those sparking hotter while still keeping the bad spark cool.
Power wouldn't be effected that bad at first b/c your leaning the bank...

etc
etc
etc
 
#93 ·
Higher revs on a sticking injector or bad spark will stabilize exhaust temps?

I understand adaptive trim but he is not trimming per primary correct its per bank.

So if with higher compression and RPM the combustion chamber pressure increases and the spark may fail more often. Then allow more unburnt gas through the primary cooling the mix in the primary but making the exhaust richer. Then adaptive trim should reduce the fuel to this bank and all primarys.
This would make those sparking hotter while still keeping the bad spark cool.
Power wouldn't be effected that bad at first b/c your leaning the bank...
Higher revs on an injector that is sensitive to low PW or is lazy under low PW ABSOLUTELY would be hidden by higher RPM. Thats the problem.

And technically, in this case, he IS trimming by cylinder as the sensor is only reading one cylinder, and the trims do affect that cylinder directly. All other bank cylinders are irrelevant for the moment.

If you look at the tables, you can see plain as day that this is a problem that is HELPED by larger PW and higher engine speed, and is primarily a low speed/low load problem. What you describe will do nothing but cloud the problem- it would be like looking for an intermittent condition only in situations where it never occurs.
 
#92 ·
I can tell you that plugs,wires,coil,injectors will not fix your problem, barking up the wrong tree, as for you problem I would lean towards a bad computer,due to all of your checking and have not bumped into anything. anybody have one you can at least use to see if it changes values on a screen?
 
#95 ·
Yesterday's tests. A few for Dan, and one that I had been pondering. I'll probably do the STFT off idle test today. Need beer; that will get the car warmed up :cheers:

First was the O2 sensor heater circuit swap where the heater controls from Bank 1 were wired to Bank 2 and visa versa.

Made this harness out of old parts. Senor wires were soldered, heater controls crimped.



Logged it for a neighborhood drive. Bank 1 - 2 disparity still there IMO.



Then I found a shade tree and pulled over to do an idle creep test whereas as soon as I stopped I started a new log file and went for 5 minutes. No throttle input whatsoever during this log.

Chart of trims read every 30 seconds.



It was then time to hit the beer store. As I pulled away I noticed everything had shifted on the trims; leaned out. The engine has not been shut off at any point here; last thing to happen was the 5 minute idle, then motor on.

Here is a brief log file of my drive away from the 5 minute idle. Compared to the longer drive log above, WTF?



^^^ That, gave me all the motivation I needed to wrap the driver side header / sensor. What I have been wanting to test. So I did.

BTW, while the car was in the air wrapping the exhaust... THE SENSOR HEATER CONTROLS WERE RETURNED TO NORMAL WIRING.

Wrapped the shit out of it, and sadly, could not reach my beer when under the car doing this :cursin:





Went for a neighborhood drive. It had been several hours since the previous drive / logs, and why did everything get leaner? Same disparity span, but everything shifted. It is Texas and it did get hotter out if that matters.

it does not appear that wrapping the sensor altered the bank gap.



Repeated the 5 minute idle test.

Boom. Driver side sensor creep at idle gone. For whatever that accomplishment matters lol.



Raw data from sensor idle tests.



I am having fun yet. I am having fun yet. I am having fun yet. I am having......
 
#96 ·
DONE (in chronological order)

* New Items

Swapped old Bosch sensors from side to side and relogged.
Checked sensor wires before replacing connectors.
Replaced sensor connectors and shortened wires back closer to factory length.
Verified sensor heater controls are wired to upstream sensors.
Checked O2 sensor ground wire at AC compressor.
Checked sensor wires after replacing connectors.
Relogged old Bosch sensors after connector replacement.
Installed new OEM NTK sensors and logged.
Pulled plugs 1 thru 8 to inspect and confirmed gaps @ 0.035 while they were out.
Checked #3 injector driver wire back to PCM.
Checked #3 plug wire back to coil pack.
Checked #3 header bolts at head for tightness.
* Swapped plugs between cyl 3 & 4 upon reinstall after inspection.
* Relogged after plug swap.
* IR temp measurement of headers and sensors at idle after log drive above.
* Swap sensor heater controls side to side.
* Idle creep test
* Wrap header / sensor on driver side

NOT DONE YET

EXHAUST
Look for exhaust leaks at collector area by disassembly.
Replace header gaskets at head / inspect.
Check all header bolts.
* Do back to back logs with header heat shields off and then on.

ELECTRICAL / WIRING
Trace all injector driver wires.
Swap O2 sensor harnesses side-side.

IGNITION
Spark check cyl #3 with extra spark plug.
Trace all spark plug wires.
Replace spark plug wires.
Replace coil pack(s).
Look for little balls of metal on the plug electrodes.

TUNING
Replace PCM.
Tune with a wideband.
Log O2 sensor voltage via PCMScan.
Use Megasquirt.
Confirm that the PCM is controlling the sensor heaters correctly.
Install wideband and compare against factory sensor.

OTHER
Leak down test.
Compression test.
Shoot headers with IR at hot 2K & 3.5K rpms.
Pull fuel system apart to look for crap in it.
Confirm normal spark and fuel on cyl #3.
* Swap injector drivers cyl 1 & 3.
 
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