Black Carbon Residual Every Morning - FiTech Tuning?

[BGBronco]

I have a 76 w/ 302, FiTech (Go Street 400), Dual Exhaust, No Catalytic Converters.

I am getting black carbon the garage floor on my morning start ups. Same amount on both sides. I've had FiTech for about a year now and this issue seems to have started or atleast became more pronounced a few months ago. I don't have a good frame of reference but seems to run fine, I have a steady idle at 750, and my IAC is in the 3-10 zone. Any tips (adjustment / otherwise) to reduce this issue? Thank you.

 

[chuckji]

No expert, but maybe an exhaust leak causing the O2 sensor to read lean which in turn causes the ECU to add more fuel. So, in the end you’re running rich, causing what you’re seeing.

 

[BGBronco]

How do I know if I have an exhaust leak?

 

[Remos69]

Two ways of doing it using a shop vac. Either pressurize using the exaust port of the vac and taping the hose to the tailpipe, use soapy water and look for bubbles. The other way is use the vacuum end taped to the exauat, use a fireworks punk or incense stick and look for areas where the smoke is sucked in. With both, make sure the exaust system is cold!! I used the second one when I didn't have a shop vac available at a friends.

 

[chuckji]

Quite a few YouTube how-to videos.

 

[BGBronco]

Well, I think I figured out the problem. I pretty much lost all power yesterday while driving and could barely make it up a small incline. I started poking around and noticed the vacuum cap on the back of my Fitech had deteriorated. My guess anyway is that this slowly deteriorated and finally the hole became large enough to really impact performance. $.45 later and I am back on the road and no more black stuff on the garage floor.!

 

[BGBronco]

Well, that didn't solve the problem. Same issue with it running rich (I'm assuming because AFR is going from 13.6 to 14.7) and bogging down to a near stop. Odd in that it doesn't happen all the time. Any thoughts?

 

[bseager]

If you have Facebook try asking the FiTech owners group. They have a lot of knowledge on the FiTech.

Sent from my SM-G892A using Tapatalk

 

[BGBronco]

I'm on the FOG waiting list!

 

[Broncobowsher]

Don't know about FiTech, but if there is a cold enrichment you should try backing that off. I had the opposite with my Holley sniper. Not enough cold enrichment and had a stumble off idle when cold. Added more fuel to clean the lean miss.

The O2 sensors don't matter here. The engine is too cold to tune with them. Extra rich is the general response to get a cold engine to start and run smooth. Keep adding more fuel but too much to actually flood it.

I can remember stories from a friend who flew the last of the big radial military planes. The startup was super rich and the description of the polywags coming out the exhaust on startup. Those engines didn't use a choke, they had a primer that shot a stream of raw gas down the engine.

Now if it isn't a too rich at startup issue, you may have bad exhaust valve guides. At shut down a little oil dribbles down the exhaust stems. At startup it gets spit out the exhaust.