What is causing blue smoke on low rpm with full throttle?

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What is causing blue smoke on low rpm with full throttle?

Postby jayz » Sat Apr 26, 2014 8:15 am

Hi,

I'm new here and hoping you can help me out.

I have a1994 corolla with a 20v engine in it, the blacktop. The engine was rebuild about 10000-12000 miles ago. It recieved new rings, crankshaft and rod bearings. The head was partly rebuild. The garage grinded the valves and replaced the valve stem seals and tested the valves for leaking.

I was noticing that it was using some oil, not very much but about 1l every 1800 miles or on 5w40 oil. I noticed sometimes after a while of constant driving that when i would go full throtlle at low rpm there was some grayish/blue smoke. I let someone drive behind me to check this and indeed at low rpm there a blueish smoke. On higher rpm there's no smoke at all, na maybe a little when shifting @the limiter :-)

Any ideas on this? Compression rates are really good, the garage told me they were around 190psi i believe with a max difference of 3psi. Also vavuum readings were good i was told.

I'm not really worried about it cause it pulls really strong but i wanna be sure so maybe i can claim warranty at the garage.

Thanks!

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Re: What is causing blue smoke on low rpm with full throttle

Postby gotzoom? » Sat Apr 26, 2014 11:19 am

Did they measure the bores for round before assembly? Did they hone the bores and did you properly bed in the rings? Blue smoke = oil burning You might try running the Toyota recommend oil too. I can't remember what it is supposed to be, but it will be in the service manual for the AE111. 5W might be too light.

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Re: What is causing blue smoke on low rpm with full throttle

Postby jondee86 » Sat Apr 26, 2014 3:18 pm

What he ^^^^ says. The BT is known for using oil when running
5W oil. Next change go to a 10W-40 and see if it improves.

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Re: What is causing blue smoke on low rpm with full throttle

Postby jayz » Sun Apr 27, 2014 8:10 am

Yes they measured the bores and it was just perfect. There was almost no wear on the cylinder walls, the rebuild shop told me they even thought the engine might had even less then the 90.000 km that was advertised. They did make new hone marks, mounted new oem piston rings and all oem bearing. No oversized was needed though.

I think i did bed in the rings well. I did a lot of different driving. Sometimes continuous driving, sometimes driving then @2k rpm, then downshift a while and drive on 3k rpm, sometimes 1/2 to 3/4 throttle, sometimes slowly accelerate. So i varied a lot in driving but did not get over 4k rpm a lot, better to say almost never ;) I had a break-in period for about 1500 miles. After that i gradually rev'd a bit more and harder.

I looked on google and found this picture in the club4ag forum: Image

Where i live it's mostly in winters not much colder then -10 (mostly even warmer) and in summer about 20-25 degrees celcius on average. So i might try a 10W40 semi synthetic then or even a 15W40? Maybe my fault was to use a full synthetic break-in oil and after that full synthetic 5W30. Some say it's better to use a non (full) synthetic oil during break-in.

Can the VVT cam gear cause oil usage too? It makes a bit noise, nothing extreme compared to videos on the internet, but still you can hear it.

Thank you so far!

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Re: What is causing blue smoke on low rpm with full throttle

Postby gotzoom? » Sun Apr 27, 2014 8:33 am

If the VVT gear seal is bad, oil can leak out, but it would leak on to the front of the engine, so you wouldn't see smoke out the tailpipe.

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Re: What is causing blue smoke on low rpm with full throttle

Postby jayz » Sun Apr 27, 2014 11:43 am

What i've also noticed by the wat, that when i drive constantly for about 100 km or so the cloud is absolutely bigger. So the longer i cruise and then accelerate the more smoke i produce.

Normally it isn't a big cloud, more like a puff. But after long driving its a pretty big puff.

Maybe that are clear clues that points to a direction?

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Re: What is causing blue smoke on low rpm with full throttle

Postby allencr » Sun Apr 27, 2014 3:15 pm

jayz wrote: ...did not get over 4k rpm a lot, better to say almost never ;) I had a break-in period for about 1500 miles.
Maybe my fault was to use a full synthetic break-in oil and after that full synthetic 5W30. Some say it's better to use a non (full) synthetic oil during break-in.


look up mototuneusa

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Re: What is causing blue smoke on low rpm with full throttle

Postby jondee86 » Sun Apr 27, 2014 3:30 pm

Current thinking on engine breakin tends towards a short period
of alternatively accelerating and closed throttle decelerating. Use
steadily increasing throttle application, reaching full throttle to
redline within the first 50-100km. With this approach, the breakin
period is over inside of an hour.

Extending periods of idling or constant speed driving at low throttle
are to be avoided, and plain mineral oil should be used for the first
1000km of driving.

It is likely that your rings have not bedded properly and this is the
cause of your oil usage. Cruising at low throttle settings creates
higher manifold vacuum and oil gets sucked into the cylinders. When
you eventually accelerate, the oil gets burned. In engines with worn
rings, this is evident in the puff of smoke that you see when getting
back on the gas at the bottom of a long down grade.

Cheers... jondee86
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Re: What is causing blue smoke on low rpm with full throttle

Postby jayz » Mon Apr 28, 2014 12:25 am

But when the rings would've not seated well and be worn, i'd most likely would have lower compression readings wouldn't i?
All the cylinders read about 190 psi which is pretty well i think.

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Re: What is causing blue smoke on low rpm with full throttle

Postby jondee86 » Mon Apr 28, 2014 2:33 am

Oil has to be coming past the rings or past the stem seals. If the valves
were loose in the guides they can ruin the seals in a short time. If you have
a bad oil control ring it can let oil into the cylinder without losing compression.
And if you PCV is blocked, it can pressurize the sump and push oil past the
rings. Change to a 10W-40 semi-synthetic and work that engine hard.
Redline it every day with plenty of engine braking from high rpm. Probably
won't fix anything, but you will have some fun :)

Cheers... jondee86
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Re: What is causing blue smoke on low rpm with full throttle

Postby jayz » Mon Apr 28, 2014 3:17 am

Redline it every day with plenty of engine braking from high rpm. Probably
won't fix anything, but you will have some fun


Haha that's true :D

I do doubt though that it's coming from the rings. I think so while compression numbers are exactly the same as after the rebuild, not the slightest change and the difference between each cylinder is minimaal with 2-3 psi max. I've also tested the vacuum readings with this website: http://www.gregsengine.com/using-a-vacuum-gauge.html and that's also superb. That's why i can't think of anything else then the head. But if the usage isn't getting worse then 1l on every 3000 km then i'm not going to do anything.

Will switching to semi-synthetic blend damage my seals maybe? Or is it absolutely no problem to switch from full synthetic to semi synthetic?

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Re: What is causing blue smoke on low rpm with full throttle

Postby jondee86 » Mon Apr 28, 2014 4:02 am

Wouldn't be a problem... at this stage you could just change to a
full synthetic in your favorite brand. I only suggested semi-synthetic
as I don't consider the extra cost of a full synthetic is justified. But
that is just me... if you can get a deal on full synth go for it :)

Cheers... jondee86
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Re: What is causing blue smoke on low rpm with full throttle

Postby jayz » Wed Apr 30, 2014 7:25 am

Today i checked the intake and there was a splash of oil in my intake. Is that normal or is it caused by too much crankcase pressure?

The pcv valve is new, what are other cause of the crankcase pressure being high? Can the head also cause pressure?

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Re: What is causing blue smoke on low rpm with full throttle

Postby jondee86 » Wed Apr 30, 2014 2:54 pm

AFAIK your car should not have a crankcase vent into the intake ?
The crankcase vents via the PCV to the common vacuum rail and
thus directly into the engine. Are you running the factory airbox ?

Cheers... jondee86
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Re: What is causing blue smoke on low rpm with full throttle

Postby jondee86 » Wed Apr 30, 2014 2:56 pm

AFAIK your car should not have a crankcase vent into the intake ?
The crankcase vents via the PCV to the common vacuum rail and
thus directly into the engine. Are you running the factory airbox ?

Cheers... jondee86
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Re: What is causing blue smoke on low rpm with full throttle

Postby jayz » Thu May 01, 2014 12:58 am

Sorry i didn't explained myself too well i think. The PCV is going to the vacuum rail yes. I've also replaced the PCV valve for a new one, but that didn't solve it. What i meant is that on the right side of the cam cover, there goes a (breather) tube to the intake air hose.
Like on this picture:
Image
Lot of people put a crankcase breather filter on it and that would most probable solve the smoke, but not the oil usage of course ;)

But what is strange in my situation is that when i drive for about 15-20 km on low rpm (cruising at about 2000 rpm and not going above 3500 rpm) and then go full throttle the cloud is first pretty big, but more greyish. The next time the cloud is little and a bit blue instead of grayish. May it be possible that i'm overfueling a bit when cruising which will create washby of the oil?

I hope i don't have to get it done all over again. It's a pretty big job to remove the engine again and lot of $$$$:( :(

I'm going to change to 10W40 semi synthetic soon and then hit it hard. Hope that somehow my oil control rings will reseat a bit if that's possible? I'm afraid it won't after the km's that are already on, but i'm hoping it ;)

EDIT: Those someone has pictures of all the hoses etc from the PCV system? Maybe i've connected some hoses in the wrong way.

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Re: What is causing blue smoke on low rpm with full throttle

Postby jondee86 » Thu May 01, 2014 2:04 am

Ahhh... I see what you mean. I think that vent hose goes back into the
intake plenum on the ST. As I understand it, the 20V PCV system has that
hose to vent excess crankcase gases, when the amount of fume being
produced by the engine is in excess of the amount of fume being passed
into the intake manifold via the PCV. The fume passed by the PCV is
factored into the engines idle air total, but any excess passed out that
vent tube just gets added to the general air intake.

So, what can be deduced from the fact that you found oil in the intake ?
Excessive crankcase fumes (blowby) normally only occur at high rpm's. But
you have not been running high rpm's. So it would appear that you may have
excessive blowby at low rpm's which is indicative of worn rings. Or in your
case, rings that have not seated properly, and are not sealing as well as
they should.

Recently I read that cast iron rings will seat in a worn (polished, not honed)
bore, but that chrome / moly rings are almost impossible to seat in a worn
bore. I wonder what kind of rings were used in your engine ? And installing
one or more of the oil scraper rings upside down can lead to excessive oil
consumption. How do the plugs look when you pull them out ? Are they all
the same colour ?

Cheers... jondee86
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Re: What is causing blue smoke on low rpm with full throttle

Postby jayz » Thu May 01, 2014 2:43 am

The rings that are used are OEM Toyota ring std size. I've only used OEM parts for the oil pump, all bearings, gasket kit, pistons, rings, etc. Only the water pump is a non Toyota brand.

The plugs look all the same without excessive oil or whatever on it. I have a picture somewhere but cannot find it right away.

What you think off my overfueling issue? Can that also be the case?

Are there things i can do to my breather system?

Thanks

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Re: What is causing blue smoke on low rpm with full throttle

Postby jondee86 » Thu May 01, 2014 3:54 am

My bad... I missed the part where you said that the engine was honed
as part of the re-build. In which case the full ring-bedding procedure
should have applied. The engine should not be over-fueling as at lower
rpm's the ECU runs closed loop with the O2 sensor. If the car is driving
well without stumbling or hesitation, your fueling should be OK.

What colour is the tailpipe ? Light to mid-brown is good... dry, sooty
black is over-fueling. Blue/grey smoke is oil, black smoke is fuel.

Cheers... jondee86
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Re: What is causing blue smoke on low rpm with full throttle

Postby jayz » Thu May 01, 2014 8:37 am

The car sometimes hestitates, but most when it's cold.

When i look at the tailpipe it's black (on the lower side), more like on this pictures: Image
Image
When i wash the car, i also wash the chrome tailpipe but within a week it's black again. Not completely but just the lower side just like on the picture. I'll try to make a picture of my tailpipe soon.

I think i might have been to sweet for the car during the break-in :(. Hope with the other oil i can get them reseat a bit more, but i think that's almost impossible :(

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Re: What is causing blue smoke on low rpm with full throttle

Postby jondee86 » Thu May 01, 2014 12:50 pm

Romp on it :) 4AGE's love to rev... rip it thru the gears at every
chance and use engine braking as much as possible. You might
get lucky and find that the oil burning comes down with 10W-40.

Cheers... jondee86
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Re: What is causing blue smoke on low rpm with full throttle

Postby jayz » Fri May 02, 2014 4:02 am

today i discovered the oil is smelling really like gas! Maybe it is overfueling? How to check for overfueling?

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Re: What is causing blue smoke on low rpm with full throttle

Postby yoshimitsuspeed » Fri May 02, 2014 10:57 pm

jayz wrote:today i discovered the oil is smelling really like gas! Maybe it is overfueling? How to check for overfueling?


Absolute best way is with a wideband gauge.
Short of that there are a couple things you can do.
Reading the plugs is somewhat informative but to do it right you would need to do a pull then cut the ignition when it's doing the behavior and coast to a stop. Pull the plugs and see how they look. This may tell you a little but it's still a pretty ghetto method and only so accurate.
Other than that you just need to decide if the smoke is black or blue.
With that said for it to actually smell like raw gas you would have to have a big issue like a cyl not firing or something.

It just occurred to me I may be misinterpreting you. Do you mean the smoke smells like gas or do you mean when you pull the dipstick out it smells like gas?

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Re: What is causing blue smoke on low rpm with full throttle

Postby jayz » Sat May 03, 2014 1:57 am

I don't have a wideband or a probe :-(

I do notice though when i just started the car of drive a short distance i can smell the exhaust gasses, then it smells rich.

But yesterday i toke the dipstick out and the oil cap and smelled the oil. And it really smells like fuel and/or exhaust gasses.

The exhaust smoke is at first dark grey and then it turns a bit blue.

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Re: What is causing blue smoke on low rpm with full throttle

Postby jayz » Sat May 03, 2014 8:27 am

I want to add that i installed a fuel pressure gauge (not regulator) and sometimes the fuel pressure drops to 0 within 1-2 hours, sometimes the fuel pressure is still pretty high after a few hours.

How long should it normally take for the fuel pressure to drop to zero? I replaced the pressure regulator with one i had around, but then it's the same. I suspect the injectors at the moment.

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Re: What is causing blue smoke on low rpm with full throttle

Postby yoshimitsuspeed » Sat May 03, 2014 10:28 am

jayz wrote:I don't have a wideband or a probe :-(

I do notice though when i just started the car of drive a short distance i can smell the exhaust gasses, then it smells rich.

But yesterday i toke the dipstick out and the oil cap and smelled the oil. And it really smells like fuel and/or exhaust gasses.

The exhaust smoke is at first dark grey and then it turns a bit blue.

The car will run rich when you first start it.
If you only let it run for a couple minutes or drive it very short distance it's possible for fuel to start to build up in the oil. This was much more of an issue in carbureted cars but could still happen with EFI in the right situation.
If the oil is thinned out with gas this could also make it much more likely to slip back past the rings and cause the motor to smoke.

I would change the oil, then take it for a long drive to burn off any remaining fuel in the pan. During this drive don't be easy on it and see if you can bed those rings a little more.

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Re: What is causing blue smoke on low rpm with full throttle

Postby jayz » Thu May 08, 2014 3:26 am

So i've let a professional company over here ultrasonic clean my injectors, unfortunately they couldn't test it afterwards cause they hadn't the tools for this specific side feed injector. :( I mounted them yesterday and the car seems to rev just a bit better.

Yesterday i've also changed my oil and filter. I bought Castrol GTX 10W40 semi synthetic blend. Today i went for a testdrive and hit her hard. In 4th gear till around 215 km/h, accelerating till about max rpm and decelerate on the engine a lot, etc etc. After that i drove the last 1,5 mile or so very gentle and then pulled the plugs right away. The engine was really hot afterwards, but that's normal cause i drove over or around 200 km/h for approx 30 miles with lot's of accelerating and decelerating.

Only downside i notice is that the VVT cam gear is making a bit more noise on this oil :(

Hope you can tell something about the color or how they look. I've made 2 pictures from all plugs:

Image

Image

Image

Image

Image

Image

Image

Image

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Re: What is causing blue smoke on low rpm with full throttle

Postby jondee86 » Thu May 08, 2014 4:13 am

Looks to me like you burned a lot of crap off those plugs !! But your
engine is not running rich with plugs that colour.

What fuel pressure does your gauge show at idle ?
Does the pressure drop when you give the engine a rev ?

Cheers... jondee86
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