Editing Forums/Z31P/z31-repairs-forums engine-mechanical/black stuff coming out of exhaust

{{ForumImport
|op_user=NJMRz88
|op_date=2009-06-22 04:52:23
|post_count=19
|archive_url=/Z31performance_archive/forum/z31-repairs-forums/engine-mechanical/7727-black-stuff-coming-out-of-exhaust.html
}}

'''NJMRz88:''' <small>(2009-06-22 04:52:23)</small>

Well the car starts up fine but when warmed up has a slight miss every now and then. i ran the codes and all that came up was the 02 so i changed it and now no codes are coming up it seemed to have helped the slight miss a little i also changed the plugs as they were a little black. i noticed that there was black stuff coming out the exhaust because when i rev the car i got all this black stuff on my mothers white car lol. i brong it to the shop and all they can say is "well your boosting turbo cars do that" but the car never did this before. i noticed on the boost gauge the vac sits a lil higher at idle then usually. before i notced the problemthe gauge would sitjust above -25 and now its sitting at almost -20..not sure whats going on but any help would be greatly appreciated

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'''michaelp:''' <small>(2009-06-22 05:03:27)</small>

Its running rich, and do me a favor and go punch whoever told you turbo cars do that when under boost in the face.

Check your CHTS (Cylinder Head Temp Sensor)

Edit: Also, -20 (or 20 in. Hg.) is proper for idling.

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'''DeleriousZ:''' <small>(2009-06-22 05:05:45)</small>

does it blow the black crap only when warm or all the time?

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'''NJMRz88:''' <small>(2009-06-22 13:49:37)</small>

Yeah it seems to do it all the time not as bad tho when the car is warmed up. and i know the car isnt suppose to do that lol thats why i didnt even let them check it out. changing the o2 helped out a little with the black stuff. now also just to let you guys know i have a 88 n/a body with all 88t engine tranny and rear and the ecu is out of an 87t. when i changed the o2 i had changed to the Titania sensor because i had the wrong one on the whole time. the only thing i didnt do was the re wireing because im not sure what to do. but the car wasnt blowing black stuff at all before i ran codes and chaged the sensor

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'''NJMRz88:''' <small>(2009-06-22 15:44:45)</small>

if someone could help me with this re wire thing to make the o2 read correctly that would be great…not sure if thats whats causing the car to blow the black stuff out. and i know its running rich im only getting abut 11mpg

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'''DeleriousZ:''' <small>(2009-06-22 17:58:57)</small>

perhaps one of your injectors are stuck open or something. take a look at your plugs again and see what they look like in each cylinder vs the other. also, remove the vacuum line running from the fuel pressure regulator, and see if there's a gas smell coming from it, you may have a ruptured disc in the pressure reg causing fuel to be sucked into the intake.

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'''NJMRz88:''' <small>(2009-06-23 02:29:13)</small>

well i wasnt able to check the plugs today but i did smell the vac hose coming off the fpr and it does semll like gas…is it the fpr or injectors? do i need to check the plugs to find out wich one it is..just trying to get the car running right this is my 3rd motor and trans im almost ready to give up on the z but she keeps telling me to fix her lol thanx though cant wait to fix this problem

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'''DeleriousZ:''' <small>(2009-06-23 05:10:31)</small>

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if the vacuum line smells like gas then there's a good chance that the pressure regulator is fubar. A way to make sure it is leaking is to disconnect the vacuum line from the intake manifold, plug the port on the manifold, and see if you get fuel coming out of the vacuum line from the pressure reg. One question I do have is for your FPR (pressure reg) do you have it going through the solenoid on the driver's side fender well or is it directly connected to the intake manifold?

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'''NJMRz88:''' <small>(2009-06-23 14:17:22)</small>

its directly to the manifold. im going to try what you said and see if theres fuel coming out of the vac line i will let you know..thanx for all your help so far

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'''DeleriousZ:''' <small>(2009-06-23 17:47:08)</small>

try not to catch yourself on fire.

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'''NJMRz88:''' <small>(2009-06-24 17:43:47)</small>

well i did check it out and no fuel came out at all i waited a few minutes and nothing the car actually seems to be acting fine now but there is still black stuff coming out the exhaust i notcied it when i put the air on yesterday.its funny because sometimes it runs fine and sum times its a little shaky. not sure whats going on i mean it runs fien when your driving i got it set at 8psi ,boost fine no hesitation. just at idle it gets a lil shaky you can hear a slight miss frmo time to time and the black stuff…you think maybe the injectors? how can i check them out? or do i just have to replace them they are all ticking so i know there working but not sure if there stuck open like you said..a buddy of mine told me maybe the ecu could that be a possibility

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'''NJMRz88:''' <small>(2009-06-25 20:27:01)</small>

any suggestions i could sure use it.

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'''Careless:''' <small>(2009-06-26 03:35:06)</small>

try unplugging the 02 completely and see if it helps.

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'''Andrew84zx:''' <small>(2009-07-10 06:06:52)</small>

did you check chts like said above? usually injetors dont just go bad, it happens but rare.I ran my na2t setup with 87t ecu with no o2 sensor stock tune and it ran fine. i dont see this being a issue.

codes are good for just a starting point, it may not throw a code but a part could not be functioning properly

my vote would be chts,maf or cas on the fritz.

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'''NJMRz88:''' <small>(2009-07-10 19:52:03)</small>

well out of no where it kind of stoped. the idle went back to normal and the boost gauge starting reading how it use to just above -25 like 24. i havent checked for the black stuff since all has been good but i will take a look at it. the maf was cleaned pretty good before i put it all back together chts havent checked that out yet or the cas i'll let you know

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'''SATAN:''' <small>(2009-07-11 05:58:19)</small>

Well, it is most likely not done doing whatever it was doing to fuck up. A bad O2 sensor will not cause you to get THAT BAD of gas mileage. 11 MGP is piss poor. Something else is definitely going wrong. When you unplugged the FPR hose from the intake manifold, I would think that would make the car run even richer that with it plugged in at idle. I HIGHLY DOUBT it is an injector problem. I too would suspect the MAF or the CHTS or the FPR. If you knew what your Fuel pressure was, that would be a good starting point. You can get a hose barb fitting for like $5 that a $20 autometer fuel pressure gauge will screw into. Put it on the line between the fuel rail and the FPR to get your reading. I don't remember what OEM pressure at idle is supposed to be but, your manual should tell you. I think it is slightly higher than normal at like 40 or 41 psi. Anyone remember?

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'''Andrew84zx:''' <small>(2009-07-11 06:17:22)</small>

'''Fuel pressure'''

At idle Approximately

kPa (kg/cm', psi) 206 (2 1.30)

The moment accelerator

pedal IS fully depressed Approximately

kPa (kglcm'. psi) 255 (2 6.37)

copied from fsm

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'''SATAN:''' <small>(2009-07-11 06:33:56)</small>

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Ok, so base pressure is 37psi. I thought it was a little higher at 40 or 41. Guess not.

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'''Andrew84zx:''' <small>(2009-07-11 06:37:30)</small>

i thought so aswell, but more like 45psi. learn something new everyday.