CompuBob

yah, there are alot of posts about compression and smoking issues, but I never make new topics so it's my turn to bitch!
anyways I got a new (to me) S5 TII a few weeks ago but after doing a lot of bodywork I finally got it on the road a week ago. The last owner put a Jspec in but never drove it because he suspected it had engine issues. I checked the compression when I got it the car ran fine, just a slight misfire while idling and the compression test read 90 in the front and 30 on the rear, I put some diesel in the combustion chamber and let it sit overnight then reassembled it and drove it for a week so far bringing it to redline every once in a while, it sounds better now and I did another test today and the compression improved a bit, the engine now reads 110 on the front and 60 on the rear.. still not good but better! I am wondering if it is a stuck seal, I don't really want to pull the turbo and inspect it through the exhaust ports, I'm thinking I will try to fill it with diesel again and let it sit all weekend.

also, if I bring it to over 5krpm and let off it will let out a nice cloud of smoke and cover everyone behind me but a few seconds later it will clear up, it really only smokes on decel, other times it's fine. Obviously my oil control seals are damaged but I was doing some reading and some people say that it very well could be a dead turbo.. my turbo is a brand new rebuild done by a reputable turbo shop, it currently only has 500km on it so I am hoping that the turbo is not the problem. But is there a way to test it out that will tell me if it's a blown turbo seal or engine seal?

oh, also I put in a bottle of Bar's Stop Smoke like some people have suggested.. it's been a day or so and I have probably driven 50km.. it seems to help a bit with the smoking but it's still bad.. I will have to give it some more time and see where it goes.

batmanfc

Check for shaft play in the turbo to start with. Wiggle the compressor wheel and it shouldn't move. Mine does about the same thing but it is N/A and I lost compression on the back rotor. Mine smokes like yours does at about the same rpm but it backfires on decel a lot too. Also, does it seem to have a decent amount of power?

CompuBob

I checked the turbo today, it's in very good shape ie. no shaft play in, out or up and down.
All of the power seems to be there, it will do a burnout at the mid/top of 1'st just by pressing the go pedal and pull hard in 2nd and never backfires, and I'm really surprised how good it is on gas. the only mod it has is a 3" turbo back exhaust and cone filter.

I used to have a 88GXL with 30psi on the rear, I still drove it for 2 years and sold it before it blew up.. except it didn't smoke at all but it was horrible on gas and shot flames every time I shifted. . it even made 121hp on the dyno

batmanfc

It may be the timing then, I would check it to make sure it is in time, it also could just be the oil control seals and nothing else. Compression is low on the back but as you said it has good power then that shouldn't be the problem. I couldn't see it being the turbo either if there is no shaft play and it has just been rebuilt. Check the timing and if it is in good time then it is probably just the oil control seals. Mine is definetly dead haha. It cranks but it has no power, maybe 40 at the most. it Definetly won't do a burnout or spin the tires or anything like that. If i come to a small hill i have to get a run and go to be lucky to pull it.

Buggy

iTrader: (8)

Those compression numbers aren't great by any means. What colour is the smoke? Also if there is any diesel left in your exhaust manifold from when you put it in the engine, that will make it smoke for a good while until all that diesel is burnt up.

CompuBob

I've put a good amount of Mileage on it since I did that, the smoke is oil.. I can definatly see and smell the large oil storm cloud as it passes my car when I come to a stop after giving it full throttle.

RandomHero

iTrader: (2)

any oil in the exhaust or intake piping?

CompuBob

no oil in the intake and when I had the exhaust off a few weeks ago to put in the centerforce clutch I didn't notice any oil in the exhaust or hot side of the turbo.

Buggy

iTrader: (8)

I'd say it has to be the oil control seals. If it were comming from the turbo you would see oil in the intercooler piping and the intake. Just my two cents.

jgrewe

iTrader: (1)

Second the oil control rings/seals. Vacuum is pulling oil passed them when you close the throttle.