dave90300zxTT

ok i need some serious help. i have done everything i can think of to fix this smoke problem and now need expert advice. just started smoking about 2mos ago and i just cant figure it out. changed pcv valves, just put in new drain back lines to turbos, new coilpacks, tps, fpr, 6ht plugs, had compression test not long ago that came out good. checked for vacuum leaks, cleaned ic pipping, so yea idk wtf to do more.... please Help?

Skully

How many miles? Could be the turbos seeping oil past the seals, does it constantly burn or on startup?

dave90300zxTT

According to the previous owner the engin was rebuilt 50k miles ago. The turbos were upgraded from t25 to t28 about 9 mos ago. I thought it was the seals on the turbos too but called the company that built them and they said it shouldnt be the turbos, key word (shouldn't ) so yea im at a loss... ive put alot of work into the car and to have this problem really sucks. Any help to pinpoint issue would be great.

dave90300zxTT

Does not really smoke until car is at temp... and is most noticed on deceleration and at stops. While on throttle dont notice as much.

Skully

Are you running cats, or test pipes? Wondering if on deceleration due to lack of pressure on one side of the impeller, its slightly pushing the seal out and leaking oil by. Have heard of it before.

dave90300zxTT

Megan raceing dp's, hks test pipes w/ hks high power cats and mufflers. I have not heard of the back pressure doing that.

dave90300zxTT

I guess tomorrow i can drop the test pipes and see if it still smokes. Thats if its being caused by the bk pressure. ..

Skully

I meant more the LACK of back-pressure, that is if the seal is going out, but I mean if its new, do you have stock cats, maybe slap them in and see....Could be pulling oil through valve seals on hard decel as well, but everything was rebuilt.

dave90300zxTT

Yea got rid of oem cats... hey would u mind calling me if thats cool? 337 540 8036

dave90300zxTT

Well thanks man for all the help... if u think of anything else that you may think it might also be let me know again thanks

ZLover4Life

It's your turbos. I'm saying this not only because the symptoms describe bad turbo seals, but because any shop that rebuilds the stock turbos (which aren't T25, by the way, but rather TB022, which is a T25/T2 hybrid) to T28s clearly doesn't know what they're doing. And even if the shop knew what they were doing, the guy who paid for it didn't, and probably cut corners.
TwinTurbo.NET: Nissan 300ZX forum - A T28 wheel will be very inefficient in a stock compressor

P.S. Turbos don't need backpressure.

dave90300zxTT

You are right... yea i pulled test pipes and its my passenger side turbo. I almost have it out right now. Pain in the *** btw without pulling motor fyi! The amount of shaft play was discusting... puttin new turbo in when this one is out... thanks for responding bud!

Skully

Glad you figured it out. I was more trying to say that with not so good seals, lack of back-pressure will accent this problem heavily. Free-flowing exhaust is best, but when you have issues to begin with, **** escalates quick. What are you going for replacement?

dave90300zxTT

Jmt turbocharger t28's . Not exactly what i want but will do for now untill full 650 build... then jwt 700bb turbos!