Code P0171, Stealership report, My attempts and current status, please advise!

[dirtking]

P CODE. Looks like your learning just like the rest of us. :) These forums are super for learning all sorts of quirks, tricks, common trouble areas and just about anything else you may need to know. Something to keep in mind about the air box not being properly snapped back together: Your MAF sensor is located just after the air filter near (or sometimes in) the air box. So any air leaking in (such as an air box that was not properly snapped back together, like you found) upstream of the MAF sensor will be detected as that leak will enter the air box then pass through the MAF sensor thus being accounted for. It's the leaks downstream (after) of the MAF sensor that gives us trouble because that added air (leaking in) does not pass threw the MAF sensor and not being accounted for which we now know is a problem for the fuel management system. In summery I don't think a leak in the filter housing upstream of the MAF sensor will cause a lean code. Hope this helps.

Mook

[P_Code_Killer]

Originally Posted by dirtking

P CODE. Looks like your learning just like the rest of us. :) These forums are super for learning all sorts of quirks, tricks, common trouble areas and just about anything else you may need to know. Something to keep in mind about the air box not being properly snapped back together: Your MAF sensor is located just after the air filter near (or sometimes in) the air box. So any air leaking in (such as an air box that was not properly snapped back together, like you found) upstream of the MAF sensor will be detected as that leak will enter the air box then pass through the MAF sensor thus being accounted for. It's the leaks downstream (after) of the MAF sensor that gives us trouble because that added air (leaking in) does not pass threw the MAF sensor and not being accounted for which we now know is a problem for the fuel management system. In summery I don't think a leak in the filter housing upstream of the MAF sensor will cause a lean code. Hope this helps.

Mook

Yes, that makes perfect sense. Thanks for the clarification.
What then, if any, is the point of snapping all three clips on the air box? It's just to keep the dirt out right? Or if any enters it's more likely to be filtered with all 3 clips secured?

[dirtking]

Originally Posted by P_Code_Killer

Yes, that makes perfect sense. Thanks for the clarification.
What then, if any, is the point of snapping all three clips on the air box? It's just to keep the dirt out right? Or if any enters it's more likely to be filtered with all 3 clips secured?

Correct, if the air filter box does not seal correctly then you are at risk of not properly filtering you air intake. :)

[P_Code_Killer]

Here is an update on my situation. CEL has been OFF for almost 5 days/300 miles; the longest time now ever since this started (I drive a lot for my job.) Never got to back-probing the MAF or checking out the O2's but had since replaced the PCV valve which I had made another thread about. So actually, that PCV valve replacement seemed to do the trick!? Or was it all the Lucas I put in my fuel, perhaps unclogging some injectors? Or the Mystery Oil added to my engine oil; which was my attempt to free my stuck rings? Who knows?, but it appears this P0171 has been killed! Now...there's bigger fish to fry in the form of my secondary, or shall I say, primary issue that Toyota found for me:

REPORT: "Engine has stuck oil rings and timing chain tensioner along with head gasket are leaking oil"

Oh s***. Is there any way a brand spankin' new grease-monkey like myself can tackle an issue that big? Well, I say yes, but I'll need some expert direction and I'm looking to any forum members which have experience in this area. I'll be taking a photo of my cylinder head cover (non-plastic) which has a conspicuous hole that looks like a screw should be in for your review. There is no visible oil leak anywhere to be found by just lifting the hood and looking inside.

Currently I have a very limited tool selection which includes:
1) A multi-head screwdriver (varying Phillips and Flat head sizes included)
2) Borrowing a basic 22 piece, 3/8 drive ratchet/socket set with non-deep variety sockets
3) Just bought a 3/8 drive torque wrench today (inch pounds measuring)
4) The 3/8 drive, 19mm deep socket for the PCV valve I removed.

That's it. I would at least like to crack the head to take a photo for analysis, but first I'll photograph the head cover to show what I'm working with and get advice on any more tools I will need as I'm just buying piece-meal for now since money is a little tight. The first pic should be up sometime tomorrow.

Other diagnostic info: Had the starter, alternator, and battery checked today, all check out good. Starting has been a little hard as in turnover time, but it always starts the first time, just holding the key for 2-3 seconds.

Random comment: My upper radiator support seal has some missing pop rivets. I went to get some replacements at Autozone. They had something like it but not identical; there's had a hex pattern on top screw in style. One of the imitations broke going in. I went to Toyota for the official goods...at $2 a pop-rivet! I really wanted the goods so I paid for 2, and kept 2 phonies that didn't break in there...but $2 for a tiny piece of plastic -- DAMN! Wise man says, pop them gently or you too may lose them inside your car.

[dirtking]

P CODE: In reference to the absence of your P0171 code it is difficult to determine what corrected the problem due to the many different corrective actions taken at the same time. One thing tho is a faulty PVC can cause a lean condition if it failed open allowing too much crank case pressure (air) into the intake system down stream of your MAF sensor.
In reference to your oil consumption you stated Toyota reported:
1) Leaking head gasket: There are three different places oil can leak to when the head gasket is compromised. A) Oil leaks outside which would be very visible to the naked eye as you will see the oil leak from the head gasket down the engine block. B) Oil leaks & mixes into the coolant system or coolant leaks & mixes with the oil, either way its very bad cuz when the coolant and oil mix, it creates a thick chocolate milk shake like sludge. Since your oil level drops we will assume your oil may be going into the coolant system. This is very easy to detect. Simply look at your coolant expansion tank (plastic tank between the rad fan & front of engine where you add your coolant) and if any oil has mixed with the coolant, your coolant will look like a thick chocolate milk shake. I am assuming that this is not your situation as this condition usually renders your coolant system dead as the water pump simply can not circulate this thick sludge thus you will over heat rather quickly, but your not over heating right? C) Oil leaks into one (or more) of your cylinders. Again usually easy to detect by pulling your spark plugs and checking that they are all the same color (should be light greyish brown color). If you have one plug that is significantly darker (almost blackish with deposits & possibly even wet with oil) then that is a good indication your head gasket is leaking oil into that cylinder. Also if you are burning a significant amount of oil this way you will probably see that tell tail sign of blue smoke exhaust from the tail pipe.
2) Leaking Timing Chain Adjuster: You state you don’t see any external oil leaks so I would assume that it is not leaking, simple as that I hope.
3) Sticking Oil Rings. If this is the case then it’s really not good. Either you deal with constantly adding oil or your engine or it will have to come out for a complete rebuild. These piston oil rings are in the heart of the engine. Going that deep into the engine should require a complete refresh of the entire crank shaft & bearings, connecting rod bearings, cylinder walls (most likely bored out or at the least honing of cylinder walls) & possibly pistons. If the cylinder walls are bored out, let’s say 20 thousands over original size, then new 20 thousands over pistons & matching piston rings will be in order to match the new cylinder bore size. But hey you never know,, constantly adding cleansing additives to your oil just may, through time, free things up,, you never know!

Your tool selection for a head job is insufficient at best (no offense). This is a big job for the average back yard mechanic. Unfortunately the 3/8” drive, inch pound torque wrench you have is for very small bolt applications (example is the head bolts need to be torqued to 36 FOOT pounds then tighten each bolt another 90 degrees in a cross pattern dictated in the manual). So the inch pound wrench is pretty much useless for most, if not all, torque applications on this job. You will need at least a ½” drive quality FOOT POUND torque wrench and I can go on and on about what other tools you should have.
I encourage you to work on your own car as much as possible. Start off small and grow from there. Also slowly build your tool selection. Your tools will most likely dictate your ability to do a job. There is an old saying: “The right tool for the right job,” This saying is GOSPEL to any competent mechanic! DAMN what a novel huh? I better stop here before they kick me out of this forum. LOL
Good luck! I hope this helps.

Mook

[tankd0g]

What year car are we talking here? I would have started with looking for an intake leak or stuck open EGR. If it's OBD-II, scanners or cables for a laptop are dirt cheap now and you can monitor your sensors.

[P_Code_Killer]

Here is the photo and my question before I reply to dirtking and tankd0g.

Is this hole (circled in red) supposed to be here (as in not filled) ? and,

What's up with this screw (vertically ellipsed)? It's just performing double duty for the plastic head cover and a bolt underneath for the metal head cover, right? And I need a deep socket to get to the one underneath?

Ok now the reply,

dirtking: Yeah I went with the shotgun approach to the code as much of it was probably warranted. To my knowledge, the PCV valve had never been changed; well it looked that way anyhow, and that was the first thing out of what I tried that made this long term of a difference. I knew I read about the problem if the PCV valve not opening and is what lead me to it, so at any rate it's done.

1) As far as the leaking head gasket, a) No, except for about 1.5 months ago I sopped up two puddles of oil sitting on the intake manifold but I believe them to be spills due to not using a funnel when topping off my oil. I have not seen any additional oil there since.
b) I should check this out anyhow but no overheating (that is if the temp is okay smack dab between C and H but not higher.
c) Okay, looks like we got a hit here on "c". I replaced the spark plugs a few weeks ago due to misfire condition on cylinder 4. All of the old ones were coated with deposits. I don't think they've ever been changed. As far as blue smoke, I haven't exactly seen that, but whenever I look back towards the tail pipe, I'm suspicious at what I see. It's not excessive, but it doesn't seem like a new cars either.

2) Leaking Timing Chain Adjuster: Looks like I get to write this one off. Yeah!

3) Sticking Oil Rings: Aw damn. Not so lucky with this one, ha ha. I've been doing the constantly adding oil thing for a while now. It doesn't help that I (enjoyably) drive it hard from time to time (not always). I'm going to keep up the additive route for a while and see where it gets me. When you say "complete refresh" what exactly do you mean? New parts or just cleaned?

No offense taken to comment about tools. I originally had the 1/2" drive torque wrench but returned it when I viewed the entire torque spec sheet for the vehicle and saw that most applications were under 100 ft/lbs and some were below 30 ft/lbs. The 1/2" drive torque wrench I bought started range was 30-150 ft/lbs so I returned it for the 3/8" drive in/lbs variety that ranged from 120-1080 in/lbs and I figured I could just do the conversion to ft/lbs by dividing the inch ranges by 12 to get 10-90 ft/lbs. Will this method not work for the example, 432 in/lbs = 36 ft/lbs?

That 90 degrees after-torque-tightening has me confused. Why do they do this? Set a foot pound rating of 36, then add 90 degrees? This increases the actual foot pounds of torque right? So why not just say 37 for instance?

As far as acquiring other tools, I had my eye on a ~190 piece Crescent brand 'Professional' set at Costco today with 1/4, 3/8, and 1/2 ratchet drivers and a whole lot of sockets for them all. Looked good and good price! Next to that was a 'dog bone' wrench that caught my eye as well.

Again, thanks for taking time to write back to someone who's new, it definitely is helpful to have feedback.

Oh and tankd0g, I have a 2001 GT. By stuck open EGR do you mean PCV, or am I right in assuming that's the same here? The laptop idea to monitor the sensors is definitely a good one!

[dirtking]

PCV = Positive Crankcase Ventilation valve. We have already discussed “Oil Rings” so I am assuming that you know what they are, where they are located and what they do. With that said there are normally 3 rings that fit into 3 individual grooves on the piston skirt. Normally 2 compression rings above one oil ring. These compression rings do not make a perfect seal so you get a little “Blow By”. This pressurized blow by blows down below the piston which pressurizes the engine crank case (inside the block). If this pressure is not relieved it builds up and eventually starts leaking out the path of least resistance which is normally areas like the oil dip stick (I have seen dip sticks actually blow right out of the dip stick tube like a bottle rocket followed by lots of oil cuz we forgot we had a plug in where the PCV valve goes, this was with a large diesel generator) crank shaft seals, valve cover gaskets, etc. At an idle there is very little blow by but at high RPM the blow by increases so the PCV valve will relieve this pressure into your intake system which burns the fumes instead of venting it out side.
EGR = Exhaust Gas Recirculation valve. I forget the actual chemical compound but at idle, but the operating temp of your cat converter will rise due to changing chemical properties in the exhaust. The proper operating temperature of your cat converter is crucial for proper pollution control as well as cat converter longevity (I have read that prolonged idling is bad for the cat). So this is what your EGR does. At idle your EGR valve should open allowing exhaust gasses to recirculate back into the intake which keeps the chemical properties in the exhaust within the proper range for proper cat converter operation.

Dirtking

[dirtking]

P CODE: I believe your conversion math is correct in ref to the inch pound & foot pound torque wrenches (cool).
In ref to the pics and that hole that is circled on your valve cover,, I assume the hole does not go thru cuz if it did I am sure you would have an oily mess. Is it threaded? Is it currently being used? If not then I would assume that it is there for an application/option that your vehicle either doesn't have or doesn't offer. I think the engine is used in other Toyota cars like Corolla. If your deep socket is not deep enough for that dual duty bolt on the front of the valve cover then hopefully you can get a wrench on the bottom nut and remove it.
In reference to tools: SOCKET POINTS: Typically there are two different kinds of socket points, 6 point and 12 point. In my opinion 12 points are useless and poor toolmanship!! (is dat a word?) LOL I have rounded off more nuts and bolt heads with a 12 point socket than I ever care to say. Then your job just got a whole lot harder and unenjoyable. GO 6 POINT as much as possible. Bring a bolt with you to the hardware store and compare the, bolt to socket, contact surface between a 6 point and a 12 point and you will what I mean.
As far as Torque technique used by Toyota,, I have seen the technique with other manufacturers as well. I think the friction of a bolt being torqued down increases dramatically as you tighten it down so I would GUESS that low torque applications are more accurate. That being said (or guessed) I can see why it’s done this way. Starting with an accurate low torque spec it’s easy to just add another 90 degree turn. I'm sure the engineers have it all mathed out. Another important issue with torqueing bolts. It is VERY IMPORTANT that your bolt threads in with NO resistance resulting from the threads. Usually a competent mechanic will "chase the threads" (Clean the threads up by running the correct tap through the treads and blowing out any debris) before torqueing them down. Think,, if you have 5 foot lbs of resistance because the treads were not cleaned up,, well I think you can see the point. Whew,, gotto go........

Bye