exhaust smoke 1986 911

[Seneca]

Last week I had a sS Wong chip and a Fab Speed exhaust installed. Sound great and love everything about it except for the small amount of blue smoke coming out, not all the time but enough. Before install car would smoke on start if it sat for more than a week.Any suggestions, thanks, Bob

[darrin]

did you have a cat before you performed the fabspeed exhaust replacement (and no longer have a catalytic converter)?

The cat "eats" minor instances of oil smoke as a fringe benefit of its exhaust cleaning.

[Seneca]

I had the cat replaced also.It just doesnt make any sense How can just a exhaust change make the car smoke??Could it be something they dipped the exhaust in but still

[DRACO A5OG]

Take a video. Has the AFM ever been tampered with?

It could be set too rich.

CAT +1, does clean up the exhaust before exiting your pipe. Without a cat you will smell a bit more as well.

Jim

Note: my baby has a vacuum leak somewhere so she runs a bit rich at idle, which is why she smells sometimes. Going to wrench with a SMOKER to finally find my leak. 45 minute job per my Wrench.

[Chris Lovell]

Right. I added a S Wong chip at the same time as a test pipe (cat delete). My little bit of smoke (with cat and no chip) turned into significant smoke at idle (no cat and SW chip). I removed the SW chip which resulted in a big reduction in idling smoke. I am thinking of reinstalling the chip but I suspect the same idle smoking result. Anything other result would be remarkable.

[GH85Carrera]

Originally Posted by Chris Lovell

Right. I added a S Wong chip at the same time as a test pipe (cat delete). My little bit of smoke (with cat and no chip) turned into significant smoke at idle (no cat and SW chip). I removed the SW chip which resulted in a big reduction in idling smoke. I am thinking of reinstalling the chip but I suspect the same idle smoking result. Anything other result would be remarkable.

I noticed the same thing.

I had a lot of smoke with the Steve's chip. I put the OEM chip back in and the smoke is virtually gone.

[DRACO A5OG]

I never had smoke come out of my exhaust with the SW 911CHIP .

[turbochad]

I'll just say it...............you need valve guides.

[DRACO A5OG]

Geez that would be unlucky

[turbochad]

It happens to all of them eventually. The cat hides the visible signs of oil being sucked through the exhaust valve guides. When the cat is out the smoke is in....

[Chris Lovell]

Yep. Both of my engines need top ends.

[darthracing]

I noticed my 86 911 with SWong Chip in it blowing lots of blue smoke at idle - not at startup, but before the engine came to full temperature - really embarrassing in stop and go, likely to get reported here in Berkeley.

Should I try removing the chip, then escalate to mechanics?

Wish Tesla could convert me, geez...

[steely]

You should determine your rate of oil consumption.

[kidrock]

Not to steal the thread, but my question seems like it may be similar to the OP's----my 3.2 seems to run a bit richer and smoke a bit more during the warmer parts of summer, yet leans out during wintertime.

WTF?

P.S.----I don't think this has anything to do with the SW chip. But I suppose I could yank the DME for the eleventy-seven bazillionth time and put the stock chip back in, and do an "empirical data" study.

[Steve W]

Blue smoke is oil burning. The cat when hot burns most of it off, when you replace that with a bypass or premuffler, you will notice the oil burning out of the exhaust.

The difference of smoking noticed between the different chips seems to occur mostly on the older 84-86 Carreras. My theory is that because the new chip updates the idle specifications from the 84-86 spec to the 87-89 spec, from 800 to 880 rpm, in addition to advancing the base idle ignition timing from 2.5 degrees ATDC to 3.5 BTDC, increases the intake vacuum enough to suck oil past marginal valve guides that previously was just borderline. The solution besides rebuilding the top end may be to reduce the oil level in the motor, lower the idle speed and/or backdate the idle specs.

[DRACO A5OG]

I have never observed blue smoke, ever. I always try to see in the side mirror what my exhaust is doing especially when I punch it. Grey = Yes but never Blue

My oil is just a hair over full at 194 degrees.

[Canuck_Targa]

I installed a SW chip this spring in my 84 and found the exact same thing. It never burned any oil, not even a puff at start up. Immediately after I installed I started smelling it at lights after the engine warmed up. I had a cat by-pass and sport exhaust before I had installed the Steve Wong chip and had never noticed it. It does smell a bit rich but it also is certainly oil burning as well. Steve's explanation on the change in advance would crate more vacuum pulling additional oil past the guides. I am not wild about sitting at lights puffing smoke out so \i may put the stock chip in for the rest of the season and give up the additional performance and redo the top end this winter. The thing that surprises me is I still do not get a puff of smoke at start up, which is more common with worn guides. I have to say the performance of the SW chip is great, and have been very pleased with it.

[stlrj]

Originally Posted by Chris Lovell

I removed the SW chip which resulted in a big reduction in idling smoke. I am thinking of reinstalling the chip but I suspect the same idle smoking result. Anything other result would be remarkable.

I suspect the SW chip fattens the idle mixture to the point where it affects the ability of the rings to seal effectively.

I experienced the same situation when my 86 3.2 was running too rich due to a bad AFM which was solved when I had it replaced with a good used one that leaned out my idle substantially and solved my annoying oil smoking at idle issue and oil consumption at the same time.



Cheers,

Joe

[darthracing]

I'll put my stock chip in tomorrrow night and compare. Stuck in SF traffic this weekend I had plenty of stinky blowing around
Thanks for the theory Steve W, it makes perfect sense, as my engine has never had a top end job.

[stlrj]

Originally Posted by Steve W

... increases the intake vacuum enough to suck oil past marginal valve guides that previously was just borderline. The solution besides rebuilding the top end may be to reduce the oil level in the motor, lower the idle speed and/or backdate the idle specs.

Steve,

That makes perfect sense if the intake guides were marginal. If that were so, then wouldn't there be a significant amount of smoke on engine overrun when intake vacuum is even higher?



Cheers,

Joe