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Discussion Starter #1
I just installed a downpipe removing all the cats,resonators, and bs from the exhaust system. After i did i reinstalled o2 sensor and reset computer for a couple hours. Today i have noticed that when i let off the throttle my cars blows smoke?? I never noticed this before whats up with that? Does anyone have a similar issue? Why is it smoking?
 

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well hope its not a blue-ish smoke... just a light gray colored smoke. once u decat, u'll notice alot more smoke puffing out post-throttle.
 

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It has been theorized that removing the catalysts and using a more direct-path silencer will produce what you are seeing. Gasses passing over a extremely hot substrate and decomposing is what a cat is all about. When you eliminate that process you are going to get what you are experiencing. BTW, it's foolish to advertise what you just did but I'm sure you could care less what I think.
 

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feeding your habit
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no one's going to report him......

the cats will burn off small amounts of oil and fuel, too much of either and cats fail (get too hot and melt) but removing them lets it pass right thru. If your up around 90K miles or beyond or 96 or older, you probably need stem seals.

fairly involved, but easy job.... do a search, I did a post on how to do this.

-M
 

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No doubt he could have marginal seals but I think he is saying he noticed this only after removing the hardware. If this is the case, why jump into the stem seal job right now?
 

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Discussion Starter #6
It does actually need a valve stem job. Not every time but depending on how the valves sit when the car is turned off sometimes it will blow a puff out when i start it up. I didnt realize that valve seals would affect the engine while it was actually running? It shouldnt theroretically. Also, they dont do emissions on vehicles pre 96' but if there ever was a problem i have the original stuff i can put back on it. It smells really bad now too :p The smoke looks more white than blue but i have only noticed it when backing off the throttle or coasting while in a low gear, and when i do this there is usually a vacuum on the turbos. Is it possible for fluids in the turbos leaking past a gasket or something? Guess im being too paranoid, since i just got it.
Thanks
 

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That's OK to want to correct things that appear wrong. We've all been there. There are members that have said what I've told you about the smoke being more obvious with the catalysts removed. There are also members who have held-off replacing seals for awhile too.
 

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Discussion Starter #8
Geez, im kindof worried about all of this. Think im going to put the oem downpipe back on because the fumes are killing me. Plus the smoke is not very pleasant either. I dont know what it could be, i spoke with Jeremy Blackwell (SpeedforSale) on the phone and described the problem and he thinks that it could be the turbos. He didnt really think it was rings or anything engine related since its 98k miles and compression were all between 152-158. Anyway when the vehicle idles for about 10 seconds or longer it will puff some smoke out. Here is a video of this, keeping in mind that its a straight pipe and exhaust installed.

http://www.mythosashard.com/suprasmoke.avi
 

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Nice looking car, and great color :eek:)

Valve seals tend to leak most in two situations.
1) At startup if car has been sitting a few hours or more
2) At high vacuum in cylinder
When the car idles for a bit then you step on the throttle, that's a time when bad valve seals are likely to let oil in to the combustion chamber.

The color of smoke is pretty blue, so I'm fairly certain it's oil burning, not water/coolant (white) or too rich a fuel mixture (black).

In general (smoke or not) running w/o a cat is going to produce more smell. A side note...the cat converters need to be fairly hot before they actually start doing much. At cold start, they shouldn't cause any more or less smoke than no cats at all. Cat light-off time varies from car to car, but generally after a minute or less of driving, most cats are functional. Some newer cars have functional cats after under 25 seconds of idling!

To feel better, you may consider putting the stock cats back in place and watching what happens. Maybe take a baseline performance measurement on your car how it is now, and how it is with stock cats. You may be suprised what you find.
 

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Discussion Starter #10
cord4530 said:
Nice looking car, and great color :eek:)

Valve seals tend to leak most in two situations.
1) At startup if car has been sitting a few hours or more
2) At high vacuum in cylinder
When the car idles for a bit then you step on the throttle, that's a time when bad valve seals are likely to let oil in to the combustion chamber.

The color of smoke is pretty blue, so I'm fairly certain it's oil burning, not water/coolant (white) or too rich a fuel mixture (black).

In general (smoke or not) running w/o a cat is going to produce more smell. A side note...the cat converters need to be fairly hot before they actually start doing much. At cold start, they shouldn't cause any more or less smoke than no cats at all. Cat light-off time varies from car to car, but generally after a minute or less of driving, most cats are functional. Some newer cars have functional cats after under 25 seconds of idling!

To feel better, you may consider putting the stock cats back in place and watching what happens. Maybe take a baseline performance measurement on your car how it is now, and how it is with stock cats. You may be suprised what you find.
Thanks that made me feel so much better about this, hehe i was getting stressed. I will say that it probably gained a good 20hp from dropping oem exhaust especially at high rpms. Has anyone attempted on doing the valvle seals themself? According to mkiv.com it looks pretty simple.
 

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cord4530 said:
Nice looking car, and great color :eek:)

Valve seals tend to leak most in two situations.
1) At startup if car has been sitting a few hours or more
2) At high vacuum in cylinder
When the car idles for a bit then you step on the throttle, that's a time when bad valve seals are likely to let oil in to the combustion chamber.

The color of smoke is pretty blue, so I'm fairly certain it's oil burning, not water/coolant (white) or too rich a fuel mixture (black).

In general (smoke or not) running w/o a cat is going to produce more smell. A side note...the cat converters need to be fairly hot before they actually start doing much. At cold start, they shouldn't cause any more or less smoke than no cats at all. Cat light-off time varies from car to car, but generally after a minute or less of driving, most cats are functional. Some newer cars have functional cats after under 25 seconds of idling!

To feel better, you may consider putting the stock cats back in place and watching what happens. Maybe take a baseline performance measurement on your car how it is now, and how it is with stock cats. You may be suprised what you find.
What is he suppose to measure? Also, I don't see anything about whether he was stone cold or warmed-up. The only thing we know is smoke on rising intake vacuum. The cats and silencer can baffle the smoke and increase the residence time of the emissions and help to burn-off some of the particulate (when up to temperature). Rather than conduct some experiment, why not just install the Random new-style close-coupled cat and rid yourself of odor and excess emissions that nobody seems to care about and get a little performance bump too.

BTW, he already knows he needs seals.
 

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dont be so stressed. i've seen alot worse.... there is blue smoke but its not that bad. if my sup's been hibernating on my driveway for a week or more.... mine will buff alot more then urs.... although mine isnt as blue (or blue at all )
 

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Discussion Starter #13
The video was shot right after i drove it back from work. I just didnt know that valve seals would do this. Correct me if im wrong but on a normal aspirated car the valves are suppose to close fully and seal the combustion chamber, i thought the valve seals were just to keep excess oil from entering the chamber when the vehicle was not running. I just cant fathom how oil is running past the valve while running, but i guess thats why this engine has vavle seals to keep the vacuum from the turbo from sucking in the oil. ** I think i answered my own question! Owell we will see what happens. ohnoes:
 

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Discussion Starter #14 (Edited)
This is really really bothering me. Here are some pics of both sides of the intercooler and the throttle body. I went to change oil today and it was way low. Its puffing smoke even worse now and there was some brownish milky stuff on the oil cap. There was also some coated on the throttlebody and both sides of the intercooler piping. Funny thing is that the inlet that goes to the turbos was clean. Here are some pics. http://www.42l.com/gallery/album15

***Oh btw! i have ecu error codes and have followed the guide but it does nothing. This could be the answer to what is wrong.
 
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