Uh oh... black spatter from exhaust

[AgaricX]

Hey all,

It's been awhile since I've even touched my 98 Eclipse Spyder, but it's now time to resume my project. I stopped work on it after I completed my AWD swap becasue I parked it on the street the DAY I finished it... and it was crushed by a garbage truck:

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I've FINALLY fixed it... by basically swapping in a complete rear shell, and I put on a brand new Robbins convertible top while fixing the notorious convertible frame support problem. SO....

It's time to turn the car on, drive it around a bit and resume engine work. After filling it with oil/coolant and cranking her up, I got a large amount of black goo spatter from the exhaust. I'd have said no problem and it will resolve, but it continues to do so even after running the car for a long period, and after multiple starts over a few weeks.

I'm not a complete luddite, and have worked on the car with buddies for a long while to do things like:
GReddy FMIC, Magnus intake, AEM fuel rail, OBX FPR, Walboro 255, HKS BOV, 3" MAF+MAFT v2, FP exhaust mani, Mishimoto radiator/fan, emissions delete, and of course the AWD swap.

However, all my buddies have now left the area, and I'm still stuck here finishing my PhD... and I suck at troubleshooting, being a biology nerd that is still learning about mech tech.

I still have the stock turbo & injectors... which is the reason I am still working on the car. I must diagnose this problem and clean up whatever mess ensured before continuing. So... here I am. Suggestions on the source of the black spatter from the exhaust? Thanks!

 

[sbiggi]

Sounds like water vapor and exhaust soot, which would be normal.

 

[WES_393]

Even after a few weeks?

Yes, it will always do it. Water and carbon "soot" are two of the byproducts from burning gasoline. As I'm sure the OP knows, Gasoline is made up of Hydrocarbons which are coincidently a big chain of Hydrogen and Carbon. When they break apart during combustion, Hydrogen is free bond with Oxygen.

Unles your losing coolant or noticeable amounts of oil, I wouldn't worry about it. Every car I've owned with open exhaust has left black marks on the garage door.

 

[Artago]

Yes, it will always do it. Water and carbon "soot" are two of the byproducts from burning gasoline. As I'm sure the OP knows, Gasoline is made up of Hydrocarbons which are coincidently a big chain of Hydrogen and Carbon. When they break apart during combustion, Hydrogen is free bond with Oxygen.

Unles your losing coolant or noticeable amounts of oil, I wouldn't worry about it. Every car I've owned with open exhaust has left black marks on the garage door.

Ah I see. I had oil going through my system due to bad valve stem seals which is different from the OP's problem.

Also, I'm running a catalytic converter so I don't see that much of the soot. Just the exhaust tip is stained black. Fair enough, thanks for the info.

 

[AgaricX]

Sounds reasonable... I have a thrupipe instead of a cat, so I can see how this would be normal. I just wanted to make certain before I buy a wideband O2 and new plugs that I wouldn't foul them quickly if something was wrong.

I AM losing coolant, but I think I have a small leak... plus I have no overflow bottle just now.

Thanks for the input!

Now to find out why I heard a 'pop' and lost HP yesterday. Can't even build pressure to vent the BOV. Time for a boost leak check.

 

[WES_393]

Well if your losing coolant and cannot find the leak then I would be very interested in doing a leak down test. It is completely normal for an engine to put out some water, but it can also be a sign that your head gasket has failed. You also need an overflow bottle since it helps regulates the level of coolant as the car warms and cools.

The loud pop and no boost is likely from a loose intake coupler or hose.

 

[sciondan]

To the OP, another thing to check for is leaky fuel injectors. if they bleed down when the car is off, then gas sits on top of the pistons breaking up the carbon. Then when running its blowing the carbon out the tail pipe. if the motor is clean internally and in good running order, you really shouldn't be having black soot shooting out. My 90 eclipse has never been rebuilt and it only has clear water drips out the tail pipe. Same goes for my 3 other vehicles.