O2 sensors, what is wrong with this pic

[metroplex]

http://www.crownvic.net/ubbthreads/user_uploads/1028615-short_term.jpg

Why is the driver side (bank 2) primary O2 sensor showing about 5%-10% leaner than the passenger side (bank 1) primary O2 sensor?

o2 sensor voltage readings are about the same for both banks.
Thanks in advance.

[TripleTransAm]

Could be anything... injectors out of balance on one side, exhaust leak on one bank, intake leak at the gasket to the head on that side, etc.

[metroplex]

These are the stock injectors.

The leak would have to be between the head and the first o2 (which means leak at the log/cat seal) and should be pretty obvious (loud, exhaust smell in engine compartment).

I was told that a deviation of 2%-4% between the banks is ideal but up to 10% is heard of, and my deviation is about 8%.

[dwasson]

Spray some propane around the lean side intake manifold and look for the RPM to increase. That would show you an intake leak.

[TripleTransAm]

The leak would have to be between the head and the first o2 (which means leak at the log/cat seal) and should be pretty obvious (loud, exhaust smell in engine compartment).

Why couldn't it be at the head-to-intake gasket area?

What is meant by injector balance is that injectors can age differently, and all it takes is for one injector to behave differently to PCM stimulus and that would throw off the behaviour of the entire bank.

One more thing I forgot to mention: when diagnosing "lean" conditions, sometimes it isn't a matter of too little fuel but sometimes too much air. Sounds the same, but in reality the O2 sensor is just that: an O2 sensor, so if a combustion doesn't happen cleanly, even if there's tons of fuel in the exhaust, the O2 sensor will just detect the unburned oxygen and will call a lean condition. You would think that OBD-II would catch such excessive misfiring, but I have no insight into Ford's engine management philosophies at that low level. In any case, in this 'too much unburned air' scenario, the cause is usually a bad injector or bad ignition.

[metroplex]

From the data, I'm guessing that the O2 sensors look 100% from the voltage transitions....

For an exhaust leak to occur it would have to be between the cylinder head and the upstream O2 sensor - putting it at the exhaust manifold/head seal or the up-pipe and exhaust manifold seal. It'd be quite obvious because I should smell a lot of exhaust in that area, right?

[TripleTransAm]

For sure, the O2 sensors results will look okay... that's what the PCM is trying to achieve. And to get the O2 sensors balanced like this, it looks like it's having to richen up one bank over the other. If the O2 sensors were still skewed, the PCM wouldn't be doing a good job of trying to achieve a good mixture.

Mating surface issues at the head-to-intake interface would admit extra air into cylinders just on that bank, no?

[MENINBLK]

I have one question ?

Do you have a "Check Engine Light" ?
The CEL will only light if the spread between the two
is large enough to be OUT OF RANGE.

So if the CEL is off, don't worry about it.

...and O2 sensors also age and give false readings...

[metroplex]

The intake manifold gasket seals are made of silicone, so they would "form" to slight imperfections in the surfaces.

There are no MIL codes, but my gas consumption is out of whack. Turning on the rear O2 sensors causes severe power loss. My O2s are 22k miles old.

[Fast4Door]

I see by your sig that you have changed heads and cams.
Have you actually measured the cam events?
A difference in cam timing bank-to-bank can give you these results. There could be some tolerance stack-up or manufacturing deviation going on.

Just a thouhgt.

[metroplex]

the heads are still stock but the cams are not. I don't have quantitative data to prove otherwise, but I recall checking out short term trims and comparing the bank data 3 years ago - before the cams and other mods. If I recall correctly back then the gas mileage sucked just as bad and there was some noticeable deviation between the banks.

I'm going to disable the O2 for bank2 and see how it runs.

[KilledKenny]

I see that you have short trim, do you have a graph of the long trim? That may also give some clues on how much the PCM has adjusted over time. I usually don't focus alot on the short trim unless I'm looking for a major vacuum leak.
Its usually the long trim that will show a problem. If long trim fuel goes either + or - 15 to 19% thats when I start to look for a concern.

[metroplex]

I was told to use short trim with adaptive off for tuning the maf transfer function, so I generally look at short trim only. Plus whenever I flash the PCM the long term gets erased IIRC.

Update:

Bank 2 cats almost caught fire... They were glowing red hot and the entire garage was filled with smoke. I shut it down for further evaluation.

Data logger shows BOTH O2 sensors for Bank 2 active. WTF? I disabled the rear O2 sensors but Bank 2 sensor 2 still showed voltage readings. Bank 1 Sensor 2 was disabled as expected.

As both cats on bank 2 glowed red dot, I noticed Bank 2 Sensor 1 (upstream of cats) stuck at 0.035V displaying the same short term trim as Bank 1 Sensor 1.

I now know why i smelled something burning... I had been driving around for the past month or so with the cats always glowing red hot. :eek:

[KilledKenny]

Its possible that the Bank 2 sensor 1 quit working and the PCM adjust the fuel trim rich on that bank trying to get the O2 sensor above .5 volts which would be why the converter is red hot.

[metroplex]

It looks more and more like Bank 2 Sensor 1 is most likely contaminated/dead.

[JMan]

Charlie,
Firstly, the short term fuel trims are just a reflection of the oxygen sensors. Typically, as the ST trims vary substantially from near zero, the long term trims will make an adjustment to bring them back to a normal range. I.E. the LT trims are what you need to look at to gather overall trim data. A 6-8% variance from zero either way on ST trim is reasonable but will vary with conditions (e.g. load, speed, temp., rpm, canister purge, et.al.) Yes, the fuel trims are all reset when you flash the PCM.

Secondly, looking at your sweeping ST trims only, I would venture to guess that both O2 sensors are working nearly equally. A high speed graph of scan data on the upstream sensors would probably confirm this.

Thirdly, if your LT trims are similarly skewed, your problem would most likely be upstream of the S1 sensors and downstream of the throttle body. Ford's fuel scheme treats each bank separately as its own fuel system. So you can rule out MAF, EGR, fuel pressure or unmetered air leaks in the intake before the throttle body.

Having said all that -

1. Check the LT trims after fully warming the engine (Don't melt the cats!). If bank two is being enriched at idle similarly to what you're seeing on the ST, raise the rpm up to ~2000 for two minutes and watch LT again. This will only serve to narrow down the problem. If the LT trims start to return to near zero or mirror the "good" bank, your problem is likely a vacuum leak at the intake or a clogged injector(s). A quick manual injector balance test (Don't try this at home, closed course - professional driver!) will gain you some direction on which one(s) are at fault. Simply disconnect the injectors on that bank one at a time and see what changes occur in the O2 sensor reading in the 1st second or two. Each one should immediately bury the O2 low (Below .100v. for a couple seconds.)This will set codes (P015x)but I'm sure you have resources to clear them afterwards. You will likely have to shut the car off after each injector is tested because the Ford OBDII computer will not return that function to the injector after about five seconds of open circuit. Don't do this unless you need to!

2. If the LT trims remain skewed or worsen at 2000 rpm. You may have a bigger problem. As mentioned before: cams or cam timing on one bank; A faulty O2 sensor (Not likely due to the equal activity B1>B2): An exhaust leak drawing air in upstream of S1; A substantially clogged injector(s); A blocked or cracked up B2 convertor(s); Mechanical sealing problem (Burned or sticking valve, seat, piston, ring etc.).
I realize scenario two is pretty ugly but you've complained of the horrid fuel economy in the past. Your fuel trims should give you some insight on that, eh?


Where's that disclaimer when you need it?:eek:
J

[SergntMac]

Great replies, eh, Charlie? And just when you thought no one here liked you.

[metroplex]

How long will it take for the LT data to settle in?

Regarding #2:
cams or cam timing on one bank; A faulty O2 sensor (Not likely due to the equal activity B1>B2): An exhaust leak drawing air in upstream of S1; A substantially clogged injector(s); A blocked or cracked up B2 convertor(s); Mechanical sealing problem (Burned or sticking valve, seat, piston, ring etc.).

I'm suspecting a blocked B2 converter namely because I have felt a severe loss of power about a week ago and intermittently before that. In the morning, my exhaust sounded funny (like something jammed up there and died) and the car had absolutely no power. It smelled like something was burning. Gas mileage was 12.5 mpg instead of the usual 14-14.5 mpg.

I've logged about 10k miles on these cams and about 5k on the PI intake (I Realize this isn't a marauder, but OBD-II is OBD-II...) and the O2s only have 22k miles on them (factory originals).

[JMan]

How long will it take for the LT data to settle in?

Regarding #2:
cams or cam timing on one bank; A faulty O2 sensor (Not likely due to the equal activity B1>B2): An exhaust leak drawing air in upstream of S1; A substantially clogged injector(s); A blocked or cracked up B2 convertor(s); Mechanical sealing problem (Burned or sticking valve, seat, piston, ring etc.).

I'm suspecting a blocked B2 converter namely because I have felt a severe loss of power about a week ago and intermittently before that. In the morning, my exhaust sounded funny (like something jammed up there and died) and the car had absolutely no power. It smelled like something was burning. Gas mileage was 12.5 mpg instead of the usual 14-14.5 mpg.

I've logged about 10k miles on these cams and about 5k on the PI intake (I Realize this isn't a marauder, but OBD-II is OBD-II...) and the O2s only have 22k miles on them (factory originals).

Your suspicions may be on the mark! A quick and easy test for clogged cats is to hook up a vacuum gauge -
1. Note vacuum at idle (Does not have to be accurately calibrated.)
2. Note vacuum at ~1500 rpm
3. Note vacuum at ~2500 rpm

The vacuum on a well breathing engine should increase when the engine speed smoothes out at each higher rpm level. If it does not, you have blockage or sealing issues. For instance, if the vacuum at idle is around 20", then I would expect to see 21-22" at 1500 rpm and 22-23" at 2500 rpm after the engine levels off at those speeds.
Of course the other tried and true method of finding a broken-up cat is to bang on the exhaust system when it is cold with a rubber mallet. If the cats rattle . . . [hear "Taps"].

Good luck with it.
Oh, by the way, I drive a waiting to be painted yellow, airport passenger picker upper, too!:D

J

Oops.
How long will it take for the LT data to settle in?
After clearing codes it will take a drive cycle of 5 to 15 minutes of varying conditions. At any given engine speed, after closed loop is under way, instantaneously!

[JMan]

How long will it take for the LT data to settle in?

Regarding #2:
cams or cam timing on one bank; A faulty O2 sensor (Not likely due to the equal activity B1>B2): An exhaust leak drawing air in upstream of S1; A substantially clogged injector(s); A blocked or cracked up B2 convertor(s); Mechanical sealing problem (Burned or sticking valve, seat, piston, ring etc.).

I'm suspecting a blocked B2 converter namely because I have felt a severe loss of power about a week ago and intermittently before that. In the morning, my exhaust sounded funny (like something jammed up there and died) and the car had absolutely no power. It smelled like something was burning. Gas mileage was 12.5 mpg instead of the usual 14-14.5 mpg.

I've logged about 10k miles on these cams and about 5k on the PI intake (I Realize this isn't a marauder, but OBD-II is OBD-II...) and the O2s only have 22k miles on them (factory originals).

Your suspicions may be on the mark! A quick and easy test for clogged cats is to hook up a vacuum gauge -
1. Note vacuum at idle (Does not have to be accurately calibrated.)
2. Note vacuum at ~1500 rpm
3. Note vacuum at ~2500 rpm

The vacuum on a well breathing engine should increase when the engine speed smoothes out at each higher rpm level. If it does not, you have blockage or sealing issues. For instance, if the vacuum at idle is around 20", then I would expect to see 21-22" at 1500 rpm and 22-23" at 2500 rpm after the engine levels off at those speeds.
Of course the other tried and true method of finding a broken-up cat is to bang on the exhaust system when it is cold with a rubber mallet. If the cats rattle . . . [hear "Taps"].

Good luck with it.
Oh, by the way, I drive a waiting to be painted yellow, airport passenger picker upper, too!:D

J

Almost forgot . . .
How long will it take for the LT data to settle in?
After clearing codes a 5 to 15 min. drive cycle with varying conditions. Without clearing diag. data, instantaneously after closed loop is achieved.

[metroplex]

Update:
I turned off adaptive fuel on a hunch that the cats were FINE but the O2 sensors were FUBAR'D.

Here are the results:
Long Term Fuel Trim: no data
Rear O2 sensors are disabled, but Bank 2 sensor 2 is still somehow active
ECT was run from ambient to 210F.

http://www.crownvic.net/ubbthreads/user_uploads/1029247-o2_voltage2.jpg
http://www.crownvic.net/ubbthreads/user_uploads/1029250-short_term2.jpg

Unless the intake manifold somehow sealed itself on bank 2 and leaked on bank 1, or the cams/cam timing changed over to bank 1, etc...

The cats did NOT glow red this time! There was a lot of water/steam from the exhaust, there was no burning smell, etc...

The only thing different now is adaptive learning is disabled.

There was no LT fuel data, I let it idle and revved it a few times in the garage for about 10 min but nothing appeared.

I hope this information helps.

[metroplex]

I wasn't lazy by not trying to swap the O2s. I tried but none of my sockets and wrenches fit the bank 2 sensor 1 O2 sensor. My O2 socket is too tall, and I need a 23 mm ? or 7/8" open ended wrench to do it, which I don't have.

The Bank 2 front O2 harness connector is way the heck up behind the LH cylinder head, which requires removing the wiper cowl assembly or hiring a contortionist. - the other 3 O2s should be a walk in the park.

[Marauder2005]

I think I might know the problem, its a Vic...

[metroplex]

I think I might know the problem, its a Vic...

It's also OBD-II/EEC-V, same as your 03-04 Marauders. Your Marauder has cats, O2 sensors, injectors, etc...

I'm looking for tech help here.

I cannot drive the car if there is a chance of a vehicle fire (which almost happened) and will most likely find a way to fix it one way or another (last resort is just driving the '81 T-bird for awhile until I buy another car). Any help would be appreciated.

[metroplex]

The Cliff's Notes version of what went differently yesterday:

Same short term trim deviation, EXCEPT Bank 2 is now normal and Bank 1 is excessively lean. Prior to yesterday, Bank 2 was excessively lean and Bank 1 was normal.

Intake manifold leaks, Exhaust manifold leaks, Injector balancing issues, etc... should not hop from bank to bank.

I will need new tools to remove the O2 sensors as my O2 socket is too tall to work properly on the driver side front O2 sensor. Maybe I need a 23mm open ended or 7/8" open ended wrench?

[StevenJ]

I don't know the emission laws for Michigan but why not just get rid of the back two cats and replace them with straigh through pipes and insert new rear O2 sensors? If you did that and you still have problems, it would rule out your rear cats being clogged. You'd still gain extra power.

[cyclone03]

This may be dumd and I may have missed something but are you sure the O2 sensor harness' are not crossed up somewhere?


B1 F to B2 R for example or somehting like that?

May not Fix the problem but may help find it.

[metroplex]

I couldn't even reach the connector for Bank 2 Sensor 1 (it's behind the LH cylinder head under the wiper assembly). None of my tools would fit the O2 sensor. I'll have to get yet another special tool to remove the O2 sensor...

My Vic has 4 cats (2 heaters near the logs and 2 rear 3-way cats). I'm not so sure the cats are clogged, because I'm getting "equal" exhaust flow with lots of water spitting out the tailpipes.

I'm not sure its the cats or O2 sensors. It could be bad gas. :help: I'll try switching gas stations or filling up on 94 octane for awhile. I've been using 87 octane (no pinging though).

[StevenJ]

I couldn't even reach the connector for Bank 2 Sensor 1 (it's behind the LH cylinder head under the wiper assembly). None of my tools would fit the O2 sensor. I'll have to get yet another special tool to remove the O2 sensor...

My Vic has 4 cats (2 heaters near the logs and 2 rear 3-way cats). I'm not so sure the cats are clogged, because I'm getting "equal" exhaust flow with lots of water spitting out the tailpipes.

I'm not sure its the cats or O2 sensors. It could be bad gas. :help: I'll try switching gas stations or filling up on 94 octane for awhile. I've been using 87 octane (no pinging though).

You sure you car is dialed in right? I know you do a lot of complaining here and especially at CV.net! You should take your car to a dyno shop and make sure that everything is set right. I really doubt you should be running regular considering all the custom engine work you had done with custom cams and the alike. Either way, throwaway the rear cats like yesterday's garbage. Replace em with straight pipe and just drill slots in em to install O2' sensors. You should gain 10-15 hp easy.

[metroplex]

I may just end up taking the car over to Lidios for a dynotune if the car runs "fine" this week. I suspect it may just be bad bad gasoline. I would like to keep the cats or just upgrade to high flow cats but the direct-fit units are backordered for months.

Plus if I chop the rear cats, what do I do about the front cats?

[StevenJ]

I may just end up taking the car over to Lidios for a dynotune if the car runs "fine" this week. I suspect it may just be bad bad gasoline. I would like to keep the cats or just upgrade to high flow cats but the direct-fit units are backordered for months.

Plus if I chop the rear cats, what do I do about the front cats?

Leave em on. I have a four cat system now but I will drop it to a two cat system later. It only cost around $200 to do so anyway. You leave the front cats a lone. If you want, you could go the fancy route, remove all four cats and buy two new custom high flow cats like the Magnaflow cats. I know people with Marauders, personally, that run with just two cats and they do fine. Then again, I don't know what the emissions rules for Michigan are so you may want to check with your state before you do anything with the cats. Do they have emissions checks in Michgan? If not, then I'd say definitely do it. If they do, well even then I still say you should go for it. Worst thing you can do is keep all four of your original cats in a box and save em just incase you need to do a emissions test.

[metroplex]

The other day I mentioned that I recorded Bank 2 Sensor 1 readings and the short term showed Bank 2 was about 10% leaner than Bank 1. The cats on Bank 2 turned red hot/transparent.

The other day, this condition switched over to Bank 1 Sensor 1 and this morning my cats on Bank 1 were red hot.

What is going on?
Bad O2 sensors?
Bad gas?

I also noticed that this morning my car was sluggish and it felt like something was clogged up in my exhaust.

The burning smell is the insulation above the cats heating up.