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Discussion Starter #1
Was just wondering if anyone had any suggestions to diagnose oil burning...

This is on a 140k mile NA-T 2JZ.

I know that ppl have suggested that slight poof of smoke after idling (Just like the Dodge Caravans) is indicative of worn valve guides or stem seals.

A Lexus technician that knows little about turbos, but alot about the N/A 2JZ is working on the car. He thinks that the piston rings are leaking. This is based on the fact that the EGR and vacuum system is picking up some oil. There are hints of oil in some lines. The lines aren't perfectly dry but aren't soaking wet either. The EGR valve is inop. and the diaphragm has oil on it. I'm not convinced its the rings, but he says that the crank case is pressurizing from blow-by.

Symptoms:
1. It doesn't smoke under a steady light load.
2. It doesn't smoke under a heavy load or under boost.
3. It doesn't smoke at idle.--- Or extremely slight smoke at idle.
4. It smokes on initial throttle tip in after acceleration.
5. Slight smoke on startup, but nothing major.
6. Smokes on right turn under very light throttle or decelerating.
7. Doesn't use much oil. 1 QT 2500 miles.
8. Smokes a lot if you really stab the throttle rev the engine, decelerate, rev the engine in a rapid fashion... vroom vroom vroom---get smoke.

Any ideas?
We're in the process of doing a compression test.

Do worn piston rings exhibit this type of problem?

Any help would be greatly appreciated.
 

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It sounds to me like the Valve stem seals are going. If you're not getting oil smoke under and steady load, or high load, i doubt its the rings. IMO..
 

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Do a search on the foruums and you'll find alot of topic related to this question.
My car smokes like hell but no lost of power. I was using the Mobile 1 10w-30. I changed to 15w-50 and that reduced the smoking by at least 85% of the time.
 
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Supra178,
I do not know how knowelgable you are about MKIV Supras but does that different viscocity have any negative effects on your car because I get a big puff of smoke only after I switch gears during high boost. I don't get smoke if I am not under high boost (>15psi) and switch gears. Do you think this will help! If you are not to sure I will probably post a question regarding it!
 

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chester said:
Supra178,
I do not know how knowelgable you are about MKIV Supras but does that different viscocity have any negative effects on your car because I get a big puff of smoke only after I switch gears during high boost. I don't get smoke if I am not under high boost (>15psi) and switch gears. Do you think this will help! If you are not to sure I will probably post a question regarding it!
Chester, since you must know everything about MKIV, then you shouldn't be here asking question. Like I had mentioned before, if you did a SEARCH (you know that little button on the top right corner) you WILL be able to find your problems. You better prey in your situation it's not your turbos going out. Don't like what I'm saying then tough!
A lot of knowledgeable supra owners are very tired of answering the same questions that's been asked over and over again, including yours.
 
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Discussion Starter #6
Too bad for me the SEARCH function has been disabled.

Is it really abnormal to have some oil residue in the vacuum lines on a normally healthy boosted car? The only thing that has me believing the tech is that the EGR system is picking up a bit of oil...

I'm already using heavier 15w-50 mobil 1 synthetic.
 
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