BinaryJay

The story thus far. During the summer I started getting P0138 (Rear O2 sensor high voltage) which would come and go on it's own. Figured okay, O2 sensor gone bad so I replaced it with an OE one and thought that was that for a few weeks.

Well it came back again, so I guess something else is causing this condition. I've also noticed lately that:

1) Exhaust smells of gas/oil a bit, not odorless. It definitely doesn't smell "sweet".

2) Whiteish smoke, quite a bit, but ONLY when I really step on the gas like accelerating hard onto a freeway. Stops when the RPMs drop and am just cruising.

3) Seems like the drivers side exhaust is "wetter" than the other one which is usually bone dry. It is mostly water, I'm sure of that, but it does seem a bit more oily/sooty than the other side. This is the same side as the O2 sensor I replaced which is the bank I'm getting the code from.

Facts:

1) Oil level seems fine, just checked it again with the car warm after sitting for a few minutes and it is reading out pretty much at the top dot maybe a bit higher.

2) There isn't any kind of indication of oil mixing with the coolant, coolant is bright red in the overflow and there isn't any kind of film on the fill cap. Dipstick the oil is clear.

3) This same thing, not the code, but the acceleration and clouds of whitish smoke has happened before after lexus changed my valve springs. When I brought it back they blamed it on "whoever last changed the oil overfilling it" (I reminded them it was them) and they claimed to just drain and fill it again and it seemed to be fine after that. Either it was different then or not as bad, because when it happened that time there was a thick film of whitish crap all over my back bumper which doesn't seem to be happening now.

So, given the fact that steam is pretty common in the winter some of it I'm sure is just steam but it does seem excessive and I don't recall it ever being something that produced massive amounts more of when you really step on the gas.

Right now I'm hoping it's one of two simple things, some oil getting burned because my PCV valve has failed causing oil to get sucked into the intake at high vacuum (high rpm/load). The other thing, is maybe EGR? Now my PCV was supposed to be replaced as part of some other TSB service I had done only a couple of years ago but whether they did it or not I don't know so it is kind of weird if the PCV is stuck already if they did. EGR I don't know much about but it is a shot in the dark. P0138 O2 code seems to have nothing to do with that O2 sensor given it's brand new, so clearly something else emissions related is causing the exhaust to be out of whack.

I was going to just buy a new PCV and EGR and replace them today but nobody has them in stock, not even for generic parts at parts stores.

Does anybody have any ideas, do my theories even make sense? Is it worth my pulling the PCV even if I don't have a replacement ready and just trying to clean it because the mystery is driving me nuts? If it was summertime I'd do it automatically but since I have to do this in a cold *** driveway I am leaning towards not taking anything off until I can just go ahead and replace it.

Would a bad MAF do this? Important to note the car has no drive-ability or starting issues so I don't suspect it. It accelerates strongly, idle is normal for the car.

ibidu1

iTrader: (1)

Sounds to me you need a good serious top engine cleaning. I would pull the throttle body and clean it out, the do a couple of engine cleaning yourself and see.. Also when was the last time you replaced your plugs, and air filter? After you do a cleaning I would drive it hard, to blow the cob webs out lol

You will know if a maf sensors is dirty or not working properly.

BinaryJay

Plugs were replaced like 10,000 km ago, top engine cleaning by lexus like 5000 km ago, throttle body was cleaned like 2000 km ago. Air filter a few thousand km ago... last oil change like 1000 km ago or so with full synthetic... everything is new. No, there is something up with the emissions system I just don't know what and I'm not at the point where I'm ready to pay lexus a diagnostic fee to tell me who knows what.

I didn't actually pull the PCV off because it was getting dark and it took me forever to find a deep socket that would actually be approximately the right size and it's really gorilla tight on there. It's getting dark soon so I just said forget it for today.

Peering through the top of the valve, it doesn't look blocked at least from the top... the hose itself looks good. There was a slight film of oily residue inside the tube leading from the PCV but it wasn't like dripping oil or anything.

ibidu1

iTrader: (1)

Wont hurt to take off the pcv valve and clean it, I would do another engine cleaning but diy. The sell seafoam with special spray nozzle, open a port in the intake and run a bottle a week and see

http://shop.advanceautoparts.com/web...oam_99984969-p

chuckGS350

http://engine-codes.com/p0138_lexus.html

GS2100

I don't want to scare you but I would *definitely do a compression check smoke is never a good sign. If all cylinders have good compression, inspect your top end gaskets and intake manifold.
Maybe Lexus techs didn't tighten a bolt or two. By the way overfilling oil will not do this. White smoke is usually coolant escaping through a seal and our cars have coolant running around the intake

BinaryJay

If cylinder compression was bad to the point where that was the cause of smoking, I imagine there would be drivability issues - loss of power etc. This isn't the case the engine runs strong all the way through and it idles relatively fine and stable.

Also, the exhaust at least when I can smell it (at idle while parked) smells of gas and not of coolant, my wife also mentioned the exhaust smells like gas (obviously does not like it). Her sense of smelling is a lot better than mine, I'm sure we're both not crazy and mistaking the smell of gas for something totally different. Thus, I am not worried really about coolant - unless there are two issues and it is both rich and only burning coolant when stepping on it on the highway.

Even then if it was burning enough coolant to make a smoke screen o fit on the highway I would kind of expect to see some residue of it in the tail pipes and on my bumper... tail pipes are sooty inside (black).

I cleaned the MAF this morning, freezing my hands in the process... if I feel up for it I am pulling the PCV off later to inspect. Checked air filter, it's spotless. No signs of leaks around the engine at least in parts I can see. Also haven't noticed any loose hoses yet.

BinaryJay

Here is the state of my PCV, it didn't look excessively dirty... holding the pcv vertically I can't blow in it from the vent tube side, and I can blow through it from the engine side BUT it takes some effort to pop it open... I get nothing through it at all until I blow hard enough to pop it then it blows freely. I thought these valves were supposed to stay open slightly pretty much all the time and never be completely shut unless there is some vacuum on the engine side.

I wish I was able to get a replacement PCV this weekend but nobody had them, so I have nothing to compare it with but it feels to me like blowing through it from the bottom up should take less pressure before it opens. I've also read that you should be able to blow through it both ways (top down only very little but something), but I get absolutely zero air through it when blowing top down. At this point I'm inconclusive on the operation of this thing, it seems like it has a tendency to stick closed more than it should but I dunno... guess I will just reinstall it (I let it soak a bit in alcohol first, didn't seem to make any difference) and just get a new one this week I guess before I give up and pay somebody to diagnose the whole thing.

Edit: Okay, after cleaning and reseating the PCV (probably my short alcohol soak did nothing), cleaning MAF, and finally resetting the ECU after the other two things didn't stop the code from keeping popping up constantly this morning during my work... I started the car up after ECU reset and noticed right away a lot less exhaust steam/smoke/whatever. Code did come up after I started the car (I don't know if it was still there after disconnecting the battery for a few minutes or not) but after resetting it it stayed away instead of coming straight back on as it was before the ECU reset. I went for a test drive around the neighborhood until the engine warmed up and then took it on the highway and gunned it ... no batmobile smoke screen this time and no more codes at least for my 15 minute trip back home. Smelled exhaust after returning, it smelled like exhaust now - I.E. not like clean winter air, but not like gas either... like exhaust. Still some steam coming out of there but my trip wasn't exactly super long and it is -5C or so so pretty normal.

I think I'm still going to just get a new PCV anyway, but I don't know if a combination of things I did made it better or if the ECU just needed to get reset for whatever (?) reason... guess I'll see if that P0138 returns or not at that point I give up and I'll pay for a diagnostic.

GS2100

Good to hear.

BinaryJay

Bleh... took the car to get dinner, was fine on the way there but code came back as soon as I started the car to come back home. It appears the error occurs every time when the car is started and the trend seems to be it happens moreso (only?) when I start the car warm.

I would think that some kind of vacuum leak somewhere would be more likely to occur after a cold soak and not when everything is hot... so yeah I'm stumped I guess I will make an appointment to have it diagnosed by hopefully somebody that knows more than I do or at the very least has access to better equipment to figure out what the heck is going on. It's driving me bananas now.

ibidu1

iTrader: (1)

Ya when you have it scanned on a real scanner they can see what exactly the sensors are doing. Right now all your doing is guessing.

BinaryJay

I wonder if it's really a catalytic converter problem, or an ECM problem. Actually I am hoping it is either or because those are still covered until September by the major emissions warranty. Will make an appt. for the closest lexus dealership and make sure they know that that downstream sensor has already been replaced though it should be on my vehicle history since I just had toyota do it a few weeks ago save myself from freezing.

I guess the cat on that bank might make sense with the symptoms too of the fuel smelling exhaust, also I suppose catalytic converter is expected to be operating more efficiently during a warm start than a cold start (though I don't really know why the code would predominantly be throw at startup rather than in the middle of a drive). Fingers crossed it's something that fits under the major emissions warranty which is really only the catalytic converters and the ECM.

Since it seems every thread about car trouble I find searching google always starts out promising (same issue, symptoms etc.) every single one of them just drops off without the OP ever posting what the eventual solution was I am going to make sure to update this thread even if nobody really cares - somebody will find it in a search in the future and be glad I did.

ibidu1

iTrader: (1)

I doubt it is an ECU issue! O2 sensor does make sense, as you are having the symptoms of it, I wonder if its a bad wire to the sensor or sensor connection. If the cat is clogged a lot of times the car has a problem of reaching higher rpm's

There is a test for the cat aswell

BinaryJay

Chances of a brand new O2 sensor less than a few weeks old being bad are pretty slim.

ibidu1

iTrader: (1)

You never know! Could have been a bad part, or poorly installed. I wonder if the other sensors are ok? They will find out once put on the scanner. Why not take it back to toyota and tell them to scan it for free see what that sensor is doing.