I've been noticing some black splattering on the floor of my garage behind my car, where my exhaust is. I have a A6/Z6 mini that I just finished that seems to be running well.

I had a burnt valve on the car before the mini me, and it was doing the same thing. What is this a sign of? I suspect I am running rich, as I smell fuel sometimes. I was under the impression that until I change my FPR from stock, I should be running lean, so now I am confused.

Any ideas what this black stuff could be? And what it is a symptom of?

 

running rich doesnt always cause the exhaust to be dis-colored. if the engine is fine (no blown seals, piston rings in good condition, gaskets in good condition), it could just be burning the excess oil that was in your exhaust pipes from the motor with the bad valve.

 

I would say you are definately running rich. I would check your vac lines from the manifold to your stock regulater it could be loose causing it to run full pres. constantly. What ECU are you running? Is it chipped? Check your oil to be sure that it isn't rich enough to let fuel drain into the crankcase as this would probably be the most damaging. Check to see if the oil smeels like gas, or when you wipe the dipstick on paper towel does it spread out quickly? Does it appear to be rich at warm-up or all the time? Let us know a few more details if the vac lines are o.k.

 

Someone correct me if wrong...but you may need new rings. The black is carbon, obviously, coming from something. Is there any smoke at all? If so, what color?

 

no need to jump to conclusions, it could just be condendation in the exhaust mixed with carbon deposits in the pipe causing it

 

I will check the vac lines tonight. My major worry is I somehow screwed up the valves during the head swap. I guess I should do a comp. test and find out.

To answer some other questions: My ECU (pm6) is not chipped (yet) I plan on getting someone to do a 1 wire VTEC and stay OBD0.

I have not noticed if it seems rich warm up only or not, but my guess is not.

Also, it has been very foggy and it was almost drizzling last night when I noticed this, so maybe it is just condensation.

Thanks for the replies guy!

 

I don't mean to worry you but condensation (water from the cat) doesn't usually break up carbon enough to turn the liquid black. It will usually come out clear. Fuel on the other hand will break up carbon and cause the discharge to be black splatter out the exhaust. IMO, you are running rich and need to figure it out. Did you check the oil yet? Was there signs of fuel? When you do a head swap it is very easy to mix up or not hook up Vac lines. How is the idle, at warm up and when up to temp?

 

Idle is great, both cold and warm. I will check the hoses and oil when I get home tonight.

I seem to be burning through my first tank of gas a bit quick, which either means rich, or I am being a bit lead footed testing out the swap...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BoostedA6 &raquo;</TD></TR><TR><TD CLASS="quote">Does it appear to be rich at warm-up or all the time? Let </TD></TR></TABLE>

My car runs PIG rich at warm-up. If I drive it not warmed up. My gas needle will drop significantly and I do throw black stuff from my exhaust once in a while. I have black spots in my driveway. That is other than normal op temp. Anybody know why this would be? Car is an MPFI STD....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fast88std &raquo;</TD></TR><TR><TD CLASS="quote">

My car runs PIG rich at warm-up. If I drive it not warmed up. My gas needle will drop significantly and I do throw black stuff from my exhaust once in a while. I have black spots in my driveway. That is other than normal op temp. Anybody know why this would be? Car is an MPFI STD....</TD></TR></TABLE>

This is just my opinion, but don't drive you car not warmed up!!! If your in a hurry at least let the idle drop before you begin driving and then baby it until it reaches operating temperature. It is one of my pet peeves when people fire up a car and tear off reving the engine. I know this probably isn't the case here but just saying if you want an engine to last let it warm up before hard driving.(not tryin' to be your grandma or anything!!) I redline my Honda's daily (one of the beautys of a Honda) and I do drive it hard! But I always make sure that it is at true operating temp before doing so.
As far as your car running rich try just pressing the gas pedal for a second and release when it is first at warm-up and see if the car almost dies or if it begins to return to warm up RPM right away. Are you running an aftermarket pres. regulator? Let me know.

 

well, I always warm my car up. (most of the time really) And when not, I do baby it I didn't know before the swap that mpfi setups run rich.... Nobody said anything about that. Now after research, I found that running an ecu for a bigger engine makes u run rich, and for a smaller engine lean.
And when I rev it, it keeps itself at warm up rpms, and even a little higher for a few seconds. Engine runs awesome, otherwise.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by fast88std &raquo;</TD></TR><TR><TD CLASS="quote"> I found that running an ecu for a bigger engine makes u run rich, and for a smaller engine lean.
</TD></TR></TABLE>
What ECU are you runnin'

 

OK. Well, I cannot see any problems with the vac hoses. Checked the FPR closely and all looks good. I don't think the oil smells like gas either. I didn't see any new spotting tonight when I came home.

Why would it ruuning rich send fuel into the crankcase?

Any other ideas?

 

Maybe it is my oil?? I just noticed I burned nearly halfway down the dipstick in ~150 miles. Havn't seen much leaking either... I put in mobil one for the last few oil changes, but now I have been reading this was a bad move on a car with 160K miles. I did notice a ton of carbon buildup on the old head and on the piston tops (which I cleaned) when I swapped out the head... Would this cause black carbon in the exhaust?

 

i know mine does the same but i am running a p28 with a mugen chip program. so i know my car is probably running rich.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by BoostedA6 &raquo;</TD></TR><TR><TD CLASS="quote">
What ECU are you runnin' </TD></TR></TABLE>

What everyone runs; PM6.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by shbrown &raquo;</TD></TR><TR><TD CLASS="quote">Why would it ruuning rich send fuel into the crankcase?
</TD></TR></TABLE>

The engine doesn't have enough time to burn the excess fuel so it basically runs down you cylinder walls removing the protective oil(damage #1) then enters the crankcase forming a mix of oil & gas. Then after your car sits the oil/gas separate and if there is enough of it the oil gets picked up through the sump and into the galleries causing a cleaning effect(not good) removing the oil from the metal causing metal to metal contact(damage # 2). While this happens some of the fuel is sent out the exhaust and can coat the o2 sensor giving false readings. Running rich can also foul plugs within a couple hundred to a couple thousand miles.
I ran extemely rich for the first 1200kms with my turbo while my basemap was being "de-bugged" and after about 500kms it was bad enough that there was fuel in the crankcase (not alot but enough that it would have been damaging over time), it fouled a set of platinum plugs, and fouled my standalone O2 sensor.
Anyhow, rich is better than detonation in the short term but over time it will kill the engine!!! Sorry for the spiel but thats my .02

 

Very interesting, thanks for the great info. So, I am not sure what to do now. Vac lines look good, especially the FPR connections. I couldn't smell fuel in the oil. I did notice it is burning a lot of oil though!

So, two questions.

I have a pressure guage for compression, but it is the push on style with a short tube. Would it be easy to find an adapter for the Honda plug?

Also, is there an easy way to measure fuel pressure? I have a guage, but don't know where to plug it in.

And, any other ways to determine if I am running rich or just burning oil?

Thanks!

-S

 

either ur running rich, maybe a exhaust leek or burning oil...

 

So how do I distinguish between these? I guess if the oil is dropping (it is) it is burning oil. But maybe it is rich too?

And how would an exhaust leak cause these symptoms?

 

you are burning oil and running rich, why didn't you put new piston rings and valve seals in while you had it apart? also why don't you get a p28 ecu so you don't run rich and wash the cyl's oil away with fuel = metal on metal contact and burn oil again.. do it right or do it over and over and over.... you decide

 

I put in new valve seals when I had it apart. I am a complete noob so I didn't want to do the rings... I am going to get my ECU chipped with Z6 maps once I get some more money!

So I am hoping to do it as right as possible....

 

that sounds like a good plan.