Lots of White smoke only after boost? Ideas on what I can try? Tons of info inside!

[teedoff00]

So a little history. I'm running a 7mgte that I built about 5 years ago. I currently store the car in Utah, as I am away for school in Michigan, so the car doesn't get ran much, only when I come home for breaks. I'm 2 weeks into my month break and I can't seem to curb this issue. Any ideas or suggestions of what I can try to reduce or eliminate the smoke would be greatly appreciated.

Problem:
After boost, my car lets off copious amount of white/gray smoke when the throttle is released and the engine sees vacuum.

It doesn't smoke while boosting, or when I am doing 2-4 gear pulls, ie. when I am shifting and seeing boost in the next gear right away.

It doesn't smoke when I am going down a hill and throw it down a gear (4K rpm) and the engine sees 20+mmHg of vacuum.

It only smokes after a boost run (the more boost the more smoke), when I let off the throttle. Ex. Merging onto a freeway, passing people in 3rd gear, exceeding the speed limit, letting off the throttle and switching to 4th gear without getting on the gas, just letting the car coast down to the speed limit. Smoke is visible a few seconds after upshift.

Car mods:
550cc injectors, Lexus AFM, Aeromotive AFPR, Apexi SAFC II, AEM Tru-Boost, Zeitronix WideBand, BOV recirculated back into accordion tube. Not sure what else is relevant.

The car runs great and boosts great, it just smokes. Lots of smoke. I have had this problem for the last 3 years or so. I suspected the journal bearing on the CT-26 (57 trim currently), when I checked it, it had quite a bit of in and out play so I had it rebuilt about 2 years ago. The new turbo has about 2500 miles on it.

Any suggestion of what I can try to reduce or eliminate the smoke would be awesome. I find the large amounts of smoke to be quite embarrassing! I tried searching and tried the suggestions that people had.
1. Rebuilt the turbo (seemed warranted, had in-and-out play)
2. Heavy vacuum, not following a boost run (Going down hill and down shifting), trying to test for leaky piston rings. Compression numbers were good last year when I checked, but dont remember the numbers now
3. Tuning with SAFC II and Zeitronix to get around 11.5 under boost.

Thanks in advance guys!

 

[steve_mk3]

From what I understand white smoke is only present under some conditions
- Water/coolent getting into the combustion/exhaust
- oil being burned in the exhaust - like blown turbo seals

did the symptoms change at all after the turo rebuild?
Have you checked for BHG?

It sounds like your turbo seals

Steve

 

[Poodles]

Sounds like turbo...

 

[Victor Charlie]

What's your oil consumption? Turbo seals can go through a lot of oil, and suddenly get worse and run your sump dry faster than you would imagine. It doesn't look like as much as it is, because the oil doesn't combust, but turns into a mist that takes up much less volume and is less visible than smoke from burned oil. If you have white smoke and you aren't going through oil, then maybe it's a coolant leak. Does sound like turbo seals again, though.

 

[suprarx7nut]

I had similar problems. New Turbo from driftmotion cured me.

Sent from my Galaxy Nexus using Tapatalk 2

 

[DOUBL3 D]

There's probably a few threads about this already but I'd be inclined to say turbo as well

 

[Grandavi]

The car I just bought (90 Supra 7MGTE) was rebuilt because the bottom end ran dry of oil because of the turbo seals losing oil. Our cars dont really warn us if its getting too low to be healthy... so the oil comment is a good hint if your losing oil abnormally, however I would think oil would burn blue, coolant burns white. I dont see how the headgasket would tie into this as the problem would show up in other areas as well. A rebuilt or new turbo isn't necessarily working simply because we assume it is, so I would personally consider looking strongly at the turbo itself.

Im just wondering if the intercooler could cause this by having fluid build up in the pipes? Just tossing it out there, because I have wondered if this could ever be an issue and if it would apply to this type of a problem.

 

[Poodles]

As it's after the engine, it's white as it's not "burning"

 

[T3rril79]

My car has the same issue for a few seconds at idle. Believing the turbo to be the source I decided to recheck the shaft play tolerences. It's not horrible but it does have more play than it started with so I am upgrading. I would at least try to rule out the snail.

 

[Maple191]

Even the TSRM says white smoke can be attribuited to blown turbo.

 

[jonahs_supra]

remove turbo down pipe and inspect for leakage

 

[teedoff00]

Thanks for the replies guys.

I still need to re-inspect the turbo for shaft play. My oil consumption is about 1/2 every 1200 miles or so. I have a small leak though in one of my oil cooler lines that I need to address.

So if it is the turbo, why does it only seem to happen upon deceleration? I would think it would smoke under boost as well, no? Unless, the pressure seals off the journal bearing in the turbo???

I haven't done a block test to see if there is any oil in the coolant, I didn't have any symptoms per say of a BHG.

Is there any other thing that could cause these symptoms other than the turbo seals? I did have it rebuilt (3 years ago), and it had no shaft play when I installed it about 2500 miles ago.

Thanks again for the help! It's much appreciated.

 

[Maple191]

Did you keep the turbo oiled while it wasnt being used. And also 1/2 a quart or 1/2 your total oil?

 

[teedoff00]

1/2 of a quart, sorry I missed that. I primed the turbo when I installed it and I went ahead and installed a Driftmotion soft oil return and inlet oil lines when I put the rebuilt turbo on.

I really am at a loss with why I get so much smoke. It smoked before I rebuilt the turbo and it smokes the same after the rebuilt turbo went on.


Thanks again for the replies!

 

[wielderofsteel]

I read alot about smokey exhausts and no one ever mentions brake fluid... if your master cylinder is leaking into the servo it will get sucked up and burnt off and cause smoke, it doesnt take alot of brake fluid to cause alot of smoke either so you may not notice the drop in fluid, especialy on a car that isnt used much, well worth looking at for anyone with mysterious smoke issues.

Another top contender may be water in the fuel through either a rusty tank, leaky cap (unlikely in a supra) or somtimes just water in the petrol from the pumps. worth looking into aswell.

 

[Poodles]

Yup, I know that from experience

Brake fluid also does bad things to your motor...

 

[toytech]

When you store for long periods you must (1) pull efi fuse (2) disconnect injector resistor (3) disconnect coil pack harness (4) crank engine until you register oil pressure (5) reinstall efi fuse (6) reconnect injector resistor and coil pack harness (7) start and idle for 15 min. *if you do not you can have premature turbo failure due to lack of oil on start up* just like a new turbo install.

Smoke on decel check shaft play in and out any is excessive .

 

[IBoughtASupra]

Just pull the EFI fuse and then crank to build oil pressure.

Pulling that one fuse stops fuel and spark. No need to touch any part of the harness.

 

[ClutchRR]

it sounds like the turbo. If it was a blown head you will have other symptoms like running rough, low on coolant, engine over heating etc.