Have an 86' with an 89' motor by previous owners and shop. They had burned a custom chip for the car and don't really have any other info since 2008 with whatever records came with it. When I start it and let it warm up, the ground gets covered with a lot of black soot coming out the exhaust. Im pretty sure this isn't normal. What could the issue be?
Would it be getting too much fuel dumped in or what? I do have a set of Lindsey chips I could throw in.
sooty exhaust issue
-
Tom
- Site Admin
- Posts: 8965
- Joined: Fri Jun 25, 2021 2:04 pm
- Location: Silicon Valley, CA
- Has thanked: 941 times
- Been thanked: 4027 times
- Contact:
Did this start out of the blue, or has it happened since you bought the car?Jc951 wrote: Mon Dec 04, 2023 9:45 am Have an 86' with an 89' motor by previous owners and shop. They had burned a custom chip for the car and don't really have any other info since 2008 with whatever records came with it. When I start it and let it warm up, the ground gets covered with a lot of black soot coming out the exhaust. Im pretty sure this isn't normal. What could the issue be?
Would it be getting too much fuel dumped in or what? I do have a set of Lindsey chips I could throw in.
Rich mixtures tend to create black smoke and black soot on the bumper over time, but rarely spits out enough soot to cover the ground. Does your car otherwise drive ok? If it was rich enough to cover the ground with soot, you would likely have other drivability issues.
When soot spits out and hits the ground, that's usually a sign of moisture in the exhaust. The exhaust pipes are lined with black soot, and it usually just sits there, but when water/coolant gets into the exhaust, you can get black spit coming out. Hold your hand in the flow and see if you get little wet black droplets. If that's what's happening, it 'could' be as simple as condensation freeing up some soot in the exhaust now that the weather is changing, but that should be short lived. Are you in a high-humidity area where everyone has tons of white steamy smoke in the morning? If so, and it the issue goes away completely after the car is warmed up, then that might be all it is.
However.... bad head gaskets can do this as well (happened to me). Look inside your oil cap to see if there is any mocha-colored sludge, which would indicate coolant in the oil. Also, look for coolant overflow after driving it hard. That's a sign of combustion pressure getting past the HG and pressuring the coolant. Other signs of a bad head gasket include sudsy or foamy coolant in the reservoir after driving hard, overheating, a constant need to vent the coolant, one or two 'steam cleaned' spark plugs, lumpy idle on cold starts (from wet plugs), and wet soot out the tailpipe even after it's fully warm.
Hope it turns out to be something simpler, but here is the Carpokes HG replacement guide if helpful:
viewtopic.php?t=351
It’s done it since I got the car last June. Haven’t done anything to it other than basic maintenance and changed the exhaust to a Fabspeed cat bypass and Broadfoot catback. Attached picture shows about 5 seconds of warm up in the garage before I pull it out to let it warm up outside. It’s definitely wet droplets. I know I have a coolant leak at the headgasket, but it’s not mixing. Car runs good and mechanic scoped and did a compression test and everything was fine.
The slight coolant leak seeps along the head gasket back to front. Of course I’m just waiting to pull the head till I have everything to do the water pump, belts and turbo refresh.
The slight coolant leak seeps along the head gasket back to front. Of course I’m just waiting to pull the head till I have everything to do the water pump, belts and turbo refresh.
- Add Pictures/Files
-
- IMG_6355.jpeg (6.9 MiB) Viewed 1066 times
-
four0four
- Posts: 184
- Joined: Wed Feb 02, 2022 10:09 pm
- Location: Western WA
- Has thanked: 22 times
- Been thanked: 32 times
If it's only while the exhaust is cool I'd...not worry about it. Water is a combustion byproduct, and if the exhaust is relatively cool some of it'll condense out. Soot could just similarly be the warmup overfueling.
How's it behave with some heat in everything?
How's it behave with some heat in everything?
-
Black944 turbo
- Posts: 216
- Joined: Thu Jul 14, 2022 7:45 am
- Has thanked: 14 times
- Been thanked: 127 times
I have no coolant leaks or oil burning issues at all and mine spits black soot when it’s cold. Keep in mind my car sits a lot and it is always humid down here, but it has always done this and it is semi normal as stated above. No soot when it’s warm.
Merry Christmas and happy holidays…I let it warm up and took it around my neighborhood. No soot shooting out after the drive…thanks for the help. Just wanted to make sure since I don’t remember my other one doing it 13 years ago