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-   -   Black smoke... (https://www.miataturbo.net/prefabbed-turbo-kits-3/black-smoke-8241/)

Fireindc 03-16-2007 01:56 PM

Black smoke...
 
So i found out my car blows black smoke at max boost (7-8psi). It blows no smoke at all (except for cold starts) other than that. I beleive this is either the oil return line not descending the whole time to the port on the engine block(stock greddy return line), or some blow by. I think it might be blow by becuse for the first time yesterday i found a little bit of oil lieing in the BOV.

How can i test this, and or fix it?

The engine is high mileage(175k) but its been rebuild around 9k miles ago.

TheBandit 03-16-2007 02:00 PM

Generally black smoke is going to be excess fuel. You might try and see what your afr's are.
-Michael-

Fireindc 03-16-2007 02:02 PM


Originally Posted by TheBandit (Post 93216)
Generally black smoke is going to be excess fuel. You might try and see what your afr's are.
-Michael-

hmm that would be great.

Im going to be ordering a wideband soon, or so was the plan.

Just wanna make sure my engines not fucked before i put more money into it haha.

Braineack 03-16-2007 02:08 PM

too much fuel....probably only happens after 5.5k

cjernigan 03-16-2007 02:10 PM

Sometimes under like half throttle acceleration i'll get a rich spot and dump a huge plume of black smoke out the back. By super rich i mean my wideband will hit like 10.8 AFR.

olderguy 03-16-2007 02:14 PM

As Braineack says, too much fuel.

One of the problems with the OEM ECU is that the internal map gets rich around 5500 rpm and up. So, if we compensate for boost with rising fuel pressure and a good pump as we increase boost, the ECU causes it to go way rich at higher rpm's because it increases the injector duty cycle in that area.

I think this is why Braineack was trying to change the rising rate of his AFPR in another thread.

Braineack 03-16-2007 02:14 PM


Sometimes under like half throttle acceleration i'll get a rich spot and dump a huge plume of black smoke out the back. By super rich i mean my wideband will hit like 10.8 AFR.
that's nothing:

http://memimage.cardomain.net/member...97_21_full.jpg

Braineack 03-16-2007 02:16 PM


Originally Posted by olderguy (Post 93228)
I think this is why Braineack was trying to change the rising rate of his AFPR in another thread.


yepper! and my damn begi fmu that i got rebuilt still doesnt work properly so i still go to 11:1 after 5.5k.

cjernigan 03-16-2007 02:18 PM


Originally Posted by Braineack (Post 93229)

HOLY CRAP, you're gonna need water injection just to clean out the motor after you get it tuned right. I don't feel so bad now.

Braineack 03-16-2007 02:35 PM

that's what happens when you dont do your math correctly. its all good now.

http://memimage.cardomain.net/member...97_34_full.jpg

PAT! 03-16-2007 02:44 PM

Maybe your bov is opening.

Braineack 03-16-2007 02:49 PM

btw, do you have your 1.8L injectors in now? probably dont need them at 5psi.

Fireindc 03-16-2007 08:55 PM

Im running about 7-8 psi brain, should i turn it up a bit?

drftem 03-16-2007 09:07 PM

not to thread jack but i am running 6psi should i put in my 1.8 injectors?

Braineack 03-17-2007 11:57 AM


Originally Posted by Fireindc (Post 93354)
Im running about 7-8 psi brain, should i turn it up a bit?

what fuel pump?


Originally Posted by drftem (Post 93360)
not to thread jack but i am running 6psi should i put in my 1.8 injectors?

a lot of factors come into play. what fuel pump, what psi level of fuel, what BHP level?

Fireindc 03-17-2007 01:54 PM


Originally Posted by Braineack (Post 93452)
what fuel pump?



a lot of factors come into play. what fuel pump, what psi level of fuel, what BHP level?

Its a stock one.

greddymx5 03-17-2007 06:13 PM

The stock pump with 1.6 injectors and vortech (greddy) afpr can supply enough for 6 psi...
There must be an explanation for the black smoke... like (earlier mentioned) a leaking bov, boost leak between turbo and intake...

Sometimes the hoses don't leak on vacuum, but on boost they will.

You should be running lean...on 7-8 psi

Fireindc 03-18-2007 10:13 PM


Originally Posted by greddymx5 (Post 93540)
The stock pump with 1.6 injectors and vortech (greddy) afpr can supply enough for 6 psi...
There must be an explanation for the black smoke... like (earlier mentioned) a leaking bov, boost leak between turbo and intake...

Sometimes the hoses don't leak on vacuum, but on boost they will.

You should be running lean...on 7-8 psi

i have 1.8l injectors.

greddymx5 03-19-2007 12:45 PM

Again, check for vacuum leaks. You have 7-8 psi, with 1.8 injectors you should be close... Do you have a IC ??

Also , check on the rear off the intake, there is a hose barb capped. Sometimes the rubber is failling. It is used for the automatic transmission.
Also check the pvc valve if you are not venting boost into the valve cover....


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