Wet black soot out of tailpipe

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Here is my build thread. I wanted to keep this question separate to hopefully generate more responses and be easier to find for people in the future.

1977 fj40, 2f, Holley sniper, long tube headers.

Upon start up and initial idle, regardless if it’s hot or cold start, siting for a week or a minute, I shoot wet black soot all over my wall and floor. It typically goes away after it reaches 160deg.

What do I need to check first? I don’t seem to have any other issues, the truck starts and runs fine.

I’ll report back with vacuum numbers. I would think potential vacuum leak causing a rich start up, but I don’t have any clear signs. Black soot does not smell like gas.

It also stays in the garage, so how much condensation could really form in the exhaust?
 
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I'd say it looks normal to me. EFI systems generally pull their air fuel ratio from a table when first started and use that data until they reach operating temperature probably 160 degrees. The settings are probably a little on the rich side because it is safer than killing a motor with settings that are to lean. Then they start making adjustments based on sensor feedback. You live in a humid part of the country so you actually can have a lot of moist air inside the exhaust. Until it heats up and evaporates it you're going to spit soot water out the pipe. Put a scrap piece of cardboard behind the pipe to keep it off the walls and tools.
 
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I'd say it looks normal to me. EFI systems generally pull their air fuel ratio from a table when first started and use that data until they reach operating temperature probably 160 degrees. The settings are probably a little on the rich side because it is safer than killing a motor with settings that are to lean. Then they start making adjustments based on sensor feedback. You live in a humid part of the country so you actually can have a lot of moist air inside the exhaust. Until it heats up and evaporates it you're going to spit soot water out the pipe. Put a scrap piece of cardboard behind the pipe to keep it off the walls and tools.
Yep looks like mine. Cardboard works perfectly haha
 
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I am okay with the cardboard in the garage, but what about in a parking lot?

Some poor soul parks their white car right next to me.

My only idea is to turn the tailpipe down, but I am not a huge fan of this.
 
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I am okay with the cardboard in the garage, but what about in a parking lot?

Some poor soul parks their white car right next to me.

My only idea is to turn the tailpipe down, but I am not a huge fan of this.
Once you start driving it you're going to find it only does it in the morning. Once the vehicle is up to temp it won't spit the soot. Besides, most of the time people tend not to want to park next to us for fear of being dinged or get rust on them. :)
 
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Here is my build thread. I wanted to keep this question separate to hopefully generate more responses and be easier to find for people in the future.

1977 fj40, 2f, Holley sniper, long tube headers.

Upon start up and initial idle, regardless if it’s hot or cold start, siting for a week or a minute, I shoot wet black soot all over my wall and floor. It typically goes away after it reaches 160deg.

What do I need to check first? I don’t seem to have any other issues, the truck starts and runs fine.

I’ll report back with vacuum numbers. I would think potential vacuum leak causing a rich start up, but I don’t have any clear signs. Black soot does not smell like gas.

It also stays in the garage, so how much condensation could really form in the exhaust?
Mine did the same - black soot all over every damn thing in its trajectory. I started using Seafoam; put in gas tank, and pulled the plugs and squirted in cylinders and let set overnight (lots of smoke when you start though). To my surprise no more black soot. I did this to the rest of my cruisers just to clean up the valves and fuel system.
 
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That’s a great point, I should have mentioned that I battled a troubled carburetor for a long time before the sniper, so I am sure my engine/exhaust is very sooted because of that.
 

middlecalf

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Didn’t see it in your build thread but did you ever pull the motor and invert it on a stand? I did that with mine and it blew black wet snot for a bit, then stopped, now it just smokes 😆. I’d drained all the oil and coolant before inverting but there was probably residual that migrated into various places and needed burning out.
 

izzyandsue

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That could be the issue. There is the Rotella T6 Multivehicle, 5w30 as I remember, that is certified for diesel and gas engines. Others are not that I have read. So a diesel oil will have different additives, much higher detergents, that will manage the typical diesel soot out of engine, and will come out of the tail pipe. I had the same issue with Delvac oil, shifted to gas engine oil, Mobil1 10w40 for our hot Southeast area, and no more soot. I had added a 2" elbow to the tailpipe to angle the exhaust diagonally towards the rear and had the black splatter on my garage floor like you have. The spot has stayed cleaned since using gas motor oil.

I gotta be careful around here, using certain oils is like religion, just a bad topic to bring up if you know what I mean. Anyway, a couple of interesting articles:


 
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I gotta be careful around here, using certain oils is like religion, just a bad topic to bring up if you know what I mean.
I know! I was hesitant to say what I used! Haha.

Good information, I’m due for an oil change anyways. I think after all my reading, I’m buying the cheapest oil on the shelf then adding ZDDP to it.
 

izzyandsue

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I dont drive my 43 too much, so using M1 full synthetic is not a big deal pricewise. I prefer the uniformity from synthetic testing, just seems to act more predictable in all conditions, stuff at the moledular level so you can't see it with the eye. With deep appoligies to the Shell, Valvoline, Castrol, Quaker State, etc disciples.

Years ago I had a white VW diesel golf, commuting from Charlotte to DC (Pentagon City) weekly. Sweet little car, 54 mpg on the highway, but the hatchback was always black. Diesel motor oil, doing its thing....
 
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Leftovers from the malfunctioning carb, How many hrs on the sniper, what sensors, are they reading properly ? there could be lots of issues. I for one think it is left overs from the bad carb. A little water and sand in the tank junked up a carb for me once and engine started that spitting coal crap, I hate it, pulled motor and gave it away.
 
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Well, I don’t think my problem warrants tossing the engine, but it sounds like a good oil change and some drive time might clear it up.
 

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