P013b popped up with check engine ... :-(

[budwich]

Well... forget the alignment "study" for now ... Driving the other day, check engine light popped up, figured initially was perhaps fuel cap issue as I don't always crank it til I get lots of "clicks".... checked / turned it a few clicks. Anyways, since it wasn't going out after a "few restarts" (probably about 10 times), I got out the "torque app", read the code, P013b... slow responding o2 going from lean to rich...hmmm. Anyways, cleared the code. Light stayed off for a few more "drives" but then popped up again... :-( Different this time though, after about 4-5 starts, light goes out. OK. Not!.... about 2-3 times later, light pops on again. Get the torque out and same code.

So now the hard part, figuring out what the heck is it complaining about. So of course, the top of the "list" indicates potentially a bad o2 sensor (unlikely but maybe). Picked up another Acdelco and dropped it in, cleared the code / reset the pcm via fuse removal. Things seemed to be fine... not!... about 5-6 starts later, code pops again. :-( During the o2 change out, the old looked fine (now a spare), cleaned the throttle body, checked the connections (vacuum wise)... maybe the gasket on the "out" side of the throttle body could be changed as it maybe is less than well sealed (it sits in a "receiver groove" in the port to the intake).

Looking thru torque, in the test results "tab", the tests associated with the o2 sensors seems to be passed / checked including the response time one... ???

One set of tests that don't seem to be working / running is an evap test for .040" (whatever this is... the .020" is successful) and the cap test.

I don't notice much / any drive issues at this point... maybe a slight mileage decrease but hard to tell with changing weather conditions and mostly city driving.

Sorry for the "long story", I guess the questions are... where do I look next? and what's up with the different evap tests / cap test ... perhaps they don't apply to trailblazers / chevy.

Thanks for any comments and guidance. Hopefully, I can get this addressed before it does a tune on my cat. One other thing, GM did replace my exhaust manifold under the recall 2 years ago. It still appears to be intacted (fingers crossed) so I don't think its an exhaust leak.

One other thing that perhaps I noticed from looking at some of the freeze frame data, is that the speed was around 50mph the couple of times that I looked at the data.... kind of strange that it was in the same general speed as city driving typically doesn't get you in that area except in certain surface road areas.

 

[budwich]

it looks like the .040 evap test doesn't apply so that's good.... not sure about a cap test. I suspect that it doesn't apply as chevy uses the results of the evap test to light a p0455 (large leak) to highlight an "issue" in the tank area including cap. Not sure where that leaves me... I guess maybe looking at fuel pressure. Looking at mis-fires, there are ones pegged "here and there" (ie. 1 on a couple of cylinders), but certainly not running away with misfiring counts.

 

[Sparky]

Bank 1 sensor 2 is the downstream not upstream sensor... seems a weird code to have since that sensor should be fairly level lined if the cat is operating properly.

At least I'd think so anyway.

 

[budwich]

yikes... your comment actually open my "stupid eye".... I was looking at the wrong sensor. Never even considered the back sensor as I thought it doesn't do much other than complain about "stink"...

You are right that it is strange but maybe my cat is done... original equipment and 160kkm. I am not sure about operation though. In "older" systems, the back sensor was supposed to just monitor cat efficiency and stay relatively stable. In newer ones, my reads seem to indicate a "slight wandering" is the "norm" and they do some form of feedback to fueling / air.... but just my limit readups.... not sure if its right or applies.

 

[budwich]

hmmmm.... looking somewhat suspicious. I see from some "googles" that there may be some "tsb" in the area for ecm updates. Not sure how / if those were done or are a "cost to user" type update. :-(

This is one that I came across for 2008 trailblazer -> PIP-4361B

 

[Sparky]

Rear sensor has no impact on fueling. There will naturally be some wander when you gas it hard or let up off the gas for example, but if it is constantly wandering then I'd be starting to think something is up with the cat. Although, you have a spare sensor now, so stick it in place of the current one and see if it still continues. If it does, then that is starting to point at the cat. If it clears up, your downstream sensor was being stupid.

 

[budwich]

sounds like a good plan.... hopefully the pigtail will reach.
searching on the "tsb", it appears to be across a number of platforms. The "one line" description is somewhat vague although some seem to point to pcm update. Its (TSB) in a "funny category" -> exterior lighting.

 

[mrrsm]

If THIS unit misbehaves... it will throw that unusual code... and if it is doing it randomly... the plug or wire harness may have a loose wire there, too:

AC-Delco MAP Sensor:



http://www.partsgeek.com/catalog/2009/chevrolet/trailblazer/fuel_injection/map_sensor.html

 

[budwich]

ok... will take a look at that .... its on the intake "snoz" from the air filter box... right? can it be cleaned?
Its wet here today so I haven't tried replacing the o2 bank2 sensor as the truck is wet under neath but the light went out by itself during start/drive today.

 

[djthumper]

Take the MAP sensor out and clean it, I would also inspect and maybe even clean the Throttle body.

 

[budwich]

yes I did the throttle body cleaning as I was looking for leaks. In the past vehicles (eg. ford), I have cleaned the MAF sensor which I think is a similar sensor... hopefully the cleaning method is similar in terms of caution and cleaner.... although the MAP doesn't look like it "disassembles" as much to get at the component parts.

 

[mrrsm]

Knowing how "Electronically Astute" you are from reading your other post installments... I'm a bit hesitant to suggest that you have not already done this...but just in case it is another base to check...from about 2.10 on... this guy has some great information about the MAP Sensor and How to make a diagnosis on the unit:

 

[budwich]

good stuff, simple... thanks. I will take a closer look at that as it hasn't ever been "serviced"... who knows what it looks like / functions... it can only help in the long run.

 

[mrrsm]

This is a "Spot On" Video on Where it is located and How the R&R is Done... Certainly easier to work on during a Rainy Day than the O2 Sensors:

 

[Mooseman]

First of all, could you give us the proper code? P031b is incorrect. The "b" should be a number. Maybe a 6?

 

[budwich]

could be... I am going by what is output to my tablet from torque. My eyes ain't the best but the "b" certainly does not look like a "6"... where are my glasses...

If you look at the tsb that I listed, I do believe the code is exists with some correlation to a TB... at least it is "googleable".

Anyways, either way, it appears to point towards sensor 2.

 

[Mooseman]

You're right. First time I've seen a code with a letter in it. My apologies.

So I would guess your downstream O2 sensot is bad. It happens. One on my Saab had issues with the heating circuit. Even if it doesn't do anything except check if the cat is working, it will throw a code if it goes bad.

 

[budwich]

actually, relooking at the code... it is still likely a "b" but it is a "B" which could be an "8". Torque when linked to the web does not find a definition / title for the code so it is somewhat strange.

Anyways, I haven't done anything to the o2 bank 2 sensor yet... its still raining here and getting the vehicle up on ramps is difficult due to the wet surfaces.

I did pull and clean both the MAP (on the intake manifold) and the AIS / AIT (i think that's what it is ... it got the hot wire components).

The MAP appears to measure up fine (as shown in posted video... thanks again) so hopefully it is OK. I did monitor the outputs via torque and they seem ok. One thing that I was "surprised" with was pulling the MAP, it was "wet". Of course, this is from over night sitting following a "one hour drive then sleep" so it is likely just condensation. The "liquid" didn't smell / look like gas, was more clear than dark, so not oil... maybe like "WDish" in terms of consistency.

I also monitored the o2 bank 2 outputs via torque for a bit. As indicated by "you's" and expected, it is basically flat at some level between .5 and 1 (scale on torque is pretty coarse... maybe .6 or .7). It does meander a bit if I "flop" the gas here and there.... but not overly. Cause it is cooler now here, one can check the exhaust system by readily seeing any "visible exhaust steam" but nothing is observed along the exhaust system except at the tailpipe... so I don't believe the exhaust system has any significant leaks.

Hopefully, when I get a chance to pull the bank 2 sensor and replace it... that will be the end of it. I have to get my truck etested in the spring so I don't need any "pop ups".

 

[mrrsm]

The "wetness" you described is likely the Oily Condensate left from the engine's vapours drawn into the Intake Manifold by way of the PCV tube under the Resonator that gathers soiled air to be drawn by a partial vacuum into the Throttle Body. From there...it gets recycled through the Intake Manifold to be re-ingested and re-burned. The other path is by way of an equally obscure "Elbow Hose" centred beneath the Intake Manifold to draw in similar vapours and condense in the upper curve of the Intake Manifold...wherein the MAP Sensor resides.

As for the O2 Sensors, both Upstream and Down ...It makes you wonder if the interference isn't further downstream at the Catalytic Converter. One of these days... GM is going to Get Wise to itself and install an Inspection Access Bung in that section of the steel exhaust pipe leading to the Catalytic Converter... just below the Tri-Bolt end of the Exhaust Manifold. If welded in facing up at a 45 Degree Bevel ...it could remain Plugged during normal operations until the time comes to remove that Sealing Plug and slide a slender 5-9 MM Mini-USb Cam downwards. Then it would be fairly easy to carefully inspect the condition of the CAT and determine if it is plugged with Carbon and/or huge flakes of Rust that often break off the inside of the Cast Iron Exhaust Manifold when flexed hard and do just as much mischief by blocking the passageway to the ceramic honeycomb innards.

 

[budwich]

I like that idea.... but I guess they figure its just a "maintenance item" (exhaust system) so if you have to "radically disturb" it to get an idea of the condition of the cat, then its probably time to do the whole system in the first place... :-(

As for the "wet substance", I figure the same... I was just surprised that there would be that much "hanging" around the sensor... can't be good for it at certain times especially in really cold weather when a degree of ice would happen for a period before / after start up. Not sure how important, it is compared to the other sensors but it appears to be relatively cheap so maybe a new one might be a good idea to see if I get anything good out of it in terms of things like gas mileage, transmission shift (not sure if gm uses some form of vacuum level to adjust shift points), and general power (as I do pull a "near capacity" trailer for vacationing).

 

[budwich]

well its dry but cool here today. Got the truck up on ramps. Took a look at bank 2 o2... sheesh!. The connector is in an ugly spot to get at... :-( AND of course, the damn sensor itself is "welded" to the exhaust. My o2 sensor "socket" is 7/8 as opposed to the 22mm (thanks to aliexpress's "inaccurate description"... another story) it needs to be so it doesn't quite grab as well as it should.... so it is a no go on getting this off at this time. :-(
Tricks? I tried a bit of heat... probably not enough. Maybe its an "omen" to leave the thing alone for now. Maybe, doing all the other stuff (cleaning / checking hoses, checking exhaust) is enough to keep the code at bay... maybe (with fingers crossed)...
I will try one more heat attempt to see if that will do it.

 

[Sparky]

To help break the sensors free on my coworker's truck I sprayed them with PB blaster, let it soak in a few minutes, then started the engine and let it run for about 5-10 min. SHut it down, then immediately sprayed the sensor hex/threads with the PB again (tried not to hit the pipe too much). This got more PB in there plus it did slightly flash cool the sensor threads which seemed to help break it free. I used a 22mm wrench with another large wrench hooked on the end to get enough leverage to break it loose.

 

[budwich]

I did try a similar effort with both PB and lots of heat, although I didn't do any "rapid cool" ... still no go at this point. I only have a 7/8 "lambda" (thanks to aliexpress) which just too big... I have order a 22mm (as stamped). Hopefully, it have something to grab still. Til then, I hope it stays working... not that its a big deal at the moment but may be an issue during the spring e-test if it acts up.

 

[mrrsm]

Most of the Rust Penetrants fall well short of their advertised results... but I have had astonishing success with THIS stuff (CRC- FREEZE-OFF) when used EXACTLY in line with their instructions and spraying periods. In the case of having Exhaust Manifold Flange Nuts rusted solid to the studs...I was able to spin them off with my fingers!:

Here are a few testimonials:

 

[budwich]

Thanks, I like to freeze too. Now I just have to find some of it locally.

Further. It appears that the stuff is hard to find locally as nobody has stock and will only order a case. I found a fastener place that carries loctite freeze and release, I wonder if it is got the same "reputation".
Of course, if I was in the states, it looks like I could walk into any advanceauto and pick it up. :-(

 

[budwich]

mrrsm... it looks like potentially the MAP sensor cleaning might have done the trick although maybe cleaning the other things didn't hurt. I haven't changed the bank2 o2 sensor yet (waiting on 22mm wrench) but the code hasn't popped back up yet and the vehicle has seen more drive time since the cleanings. It is running better so all in all, the effort along with the help / comments has been very worthwhile... thanks to all

PS. I came across GUMOUT freeze and release at homedepot, hopefully it will be just as good as CRC freeze off

 

[budwich]

I guess I was too optimistic... :-(
The code popped up again. This after about 10 days of normal city driving.
I looked at the test results under torque. It would appear that the test results for that O2 sensor (ie. bank 2) has an "over condition" in the "fail item"... didn't write down the exact numbers down but something like .754 versus the max of .730.... which would seem to indicate a slight "richness" post cat. Not sure how to understand this... not enough oxygen coming back into the stream post cat... cat no longer scrubbing out enough bad gases to create sufficient oxygen.

I haven't changed the o2 sensor yet as I am still waiting for the 22mm lambda socket.

 

[mrrsm]

I'm probably making this suggestion a bit too late to make any difference... but... when I was attempting to remove the Upstream O2 Sensor with a Harbor Freight "Split Socket" High Grade Steel unit and a 1/2" Ratchet... First of all... I could NOT for the life of me get enough "Mechanical Advantage" sufficient to back the damned thing out of the Exhaust Manifold. At one point... I was afraid that I'd use so much "Old Man Strength" That I'd wind up either breaking off the Exhaust Manifold Bolts in the Exhaust Ports of the Head... or wind up Cracking the Manifold at the O2 Sensor Cast Iron Bung.

But then I got wise to myself and kept on looking on line until I found THIS tool... and even with its clever design...I still had to go One Step Further...and cut off one of the two long handles from an Old Yard Pruning Branch Cutter I had so the inside diameter would be large enough to slip the handle of this weird tool deep inside. Lo and Behold... this arrangement gave me all of the help I needed to use it in combination with the Freeze-Off Spray. After applying some very small coaxing pulls on the damned thing... The O2 Sensor finally came out without any difficulty. So if it comes down to cases... Here is hoping they sell these in the Auto Parts Stores near to where you are:

 

[budwich]

thanks again.... I have seen that one on-line also ($40 tax in) most of the 22mm stuff in the area is in the $30-40 range which for the life of me, I can't come to grips with ... especially since I have two o2 sensor "sockets" which of course are 7/8 which will not grab the sensor correctly.

Access with a long enough bar is fine on the bank2 o2 sensor. I haven't quite given in to cutting the wiring off and just using a normal 22 mm socket which I do have. That is my "fall back". I am concerned that I may not be able to disconnect / connect a replacement sensor as the connector is in a bit of a tough place when lying on ones back.... so I don't want to get too "aggressive" quite yet. My hoping that "china express" will happen sooner than later... It does give me some time to keep spraying some pb every once in a while to help things along.

 

[Mooseman]

At worse, cut the wires so you could splice them back together if you can't get it off.

 

[budwich]

well the "china express" failed to come thru again.... "lost in transit"... :-(
anyways, the code hasn't come back so perhaps the cool weather has helped the sensor / cat out a bit.

anyways, haven't totally given up although it is now on the back burner with the weather and "lack of regular code".

My question at this point is ... has anyone ever "de-constructed" the connector on the o2 sensor as opposed to cutting and splice. By "de-constructed", it appears at first glance, that the back side of the connector can be "unclicked" in some form and the pins / wiring removed from the "oversize plug" such that a normal box end 22mm wrench can be used (ie. slipping the pins / wiring thru the box end).... successfully and then "rebuilding" the connector?

 

[mrrsm]

Call me "Crazy" here... but rather than cutting the O2 Sensor Wire... if you can get your hands on a few extra Sturdy, Long 6 Point 22MM Sockets... I would Chuck one of them in a Vise and use a 7" Harbor Freight Angle Grinder and cut a slice between the Flats just wide enough to slip the Wire through and act like a "Store Bought Tool"... and after Douching the Hell out of the Sensor Thread Lines with Freeze Off ... Slip on the socket with a decent Breaker Bar (...after pre-planning your maneuver of course)... then you can apply gradual pressure while the Sensor is sill Ice Cold and Soaking Wet with the Penetrating Stuff and see if you can coax the damned thing loose.

 

[Sparky]

But what if I want to use my Makita 6" angle grinder?

 

[budwich]

Yep... that was my alternative. Actually, HD up here has a 22mm box end wrench that I was going to "slice" with a "cutoff" tool. The reason for the box end choice is that I have one "socket" type o2 "wrench" (7/8) that is "sliced" by design (ie its is an o2 socket) BUT the walls of the socket are too thin and "flex" just enough that even on a 7/8 o2 plug, it does have a problem "sliding" around the o2 nut.

Anyways, I am going to look closer at the "replacement" o2 sensor and see if I can try the connector disassemble without destroying things.

 

[mrrsm]

But what if I want to use my Makita 6" angle grinder?

The reason I specify the 7" Disc is because if he buys the High Grade Steel 22MM Sockets that are "Impact Wrench Capable" ...A Smaller Disc size will NOT be able to spin fast enough to quickly burn through the cut line and it can become an exercise in futility. The 7" Disk has the higher transitional edge velocity that can generate enough friction and remain so long enough to quickly cut out the segment line on the socket ...and not heat the thing up slowly enough to reduce its overall strength.

 

[budwich]

Looked at the o2 sensor end connector... the back retainer comes off easy enough but then there doesn't appear to be an easy way to get at the pins in terms of release from the connector block holder. :-(
So it appear that the "slotted box end" will be my next step when I get at this again.

 

[jsheahawk]

As MRRSM suggests, I made my own slotted O2 socket. It isn't pretty, but it works.

 

[mrrsm]

To be effective and reliable enough... the contacts holding the wires to the O2 Sensor would have to be Silver Soldered on and the temperature that stuff melts at is around a very tricky 1,500 Degrees Farenheidt... so getting them on and off in the narrow and claustrophobic location of the passenger side Engine Nacelle would be very problematic.

I was thinking that when you use your "Sliced, Off-Set Box End Wrench" idea... that if you encircled the Outside Diameter with a Stainless Steel Radiator Hose Clamp... perhaps you could tighten it down snugly enough to act as a buttress and prevent the slender tool from spreading open when the Heavy Torque is being applied and save yourself some badly skinned knuckles as the Sensor unwinds from the Exhaust Manifold without any "slippage". ;-)

 

[Mooseman]

Ah geez. To install the sensor, you can use the open end of a regular wrench. I just did that to another vehicle. If it's a new sensor, no cutting required. I don't have the figure in front of me but it shouldn't be a lot of torque. Just snug, like a spark plug.

 

[mrrsm]

I appreciate your sense of exasperation at all this seemingly unnecessary focus on tool use and exotic designs to do what a simple Crescent Wrench should be able to accomplish. But the attached photos show the real exasperation when Mechanics' common problem is not involving the installing O2 Sensors... but getting the Damned Things out first without turning what should be a simple job into a complete Nightmare.

This is not an abstract idea for me... as I have made the mistake of trying to use a Basic Tool that lead to what can be seen in these images ...and instead... I wish I had let my imagination dwell on something less conventional ...and more likely to extract these sensors... no matter how outlandish the tool I dreamed up seemed to be: