Super Rich on Stock car

[Infiltrate2000]

My car is running extremely rich. Setup is completly stock. I can see the black deposits on my driveway and when wot, a cloud of black smokes comes out. My gas mileage is horrible, i get about 16 miles a gallon all highway with easy driving.

I did a leak test and only found a small leak which i fixed. But the problem is still there. Any help would appreciated. I have no idea what to do. Did tons of search, and everything pointed to checking for leaks. o2 sensor is brand new btw.

 

[hopwoodp]

My car is running extremely rich. Setup is completly stock. I can see the black deposits on my driveway and when wot, a cloud of black smokes comes out. My gas mileage is horrible, i get about 16 miles a gallon all highway with easy driving.

I did a leak test and only found a small leak which i fixed. But the problem is still there. Any help would appreciated. I have no idea what to do. Did tons of search, and everything pointed to checking for leaks. o2 sensor is brand new btw.

I once had a bad Mass airflow sensor that caused me to run super rich. I got 5 miles per gallon. I was the only one that figured that out. I checked spark plugs, wires, o2 sensor. You name it, I checked it out and that how I figured my mass was trash.

 

[mach4g63t]

How's your turbo and boost levels? Got an aftermarket boost gauge? Pull the intake and check it for shaft play. If you have no leaks, then just no turbo boost at all could be a problem.

 

[romeen]

Do you have a CEL?

Even though you put in a new O2 sensor you may want to use a multimeter to double check it's function.

Pull your plugs to see if all cylinders are running rich (black plugs smelling like fuel) or if just one or two. If only one cylinder is this way then consider a leaking/stuck open fuel injector. You can listen with a stethoscope placed on the injector during idle to check for a cyclic clicking sound. The rate should increase with rpms.

If all show signs of running rich you might start by checking the fuel return lines for kinks. You might also consider getting a fuel pressure guage to see if fuel pressure is too high. B&M makes one that you can attach to the top of the fuel filter.

 

[mach4g63t]

I once had a bad Mass airflow sensor that caused me to run super rich. I got 5 miles per gallon. I was the only one that figured that out. I checked spark plugs, wires, o2 sensor. You name it, I checked it out and that how I figured my mass was trash.

that's a good point to. the car can be stock, but check to see if the MAS has been hacked. I had the upper honey comb hacked on mine when I originally bought it and that 'cause me to run really rich under boost too. Are you running rich when WOT or even at idle and cruising speed?

 

[hopwoodp]

that's a good point to. the car can be stock, but check to see if the MAS has been hacked. I had the upper honey comb hacked on mine when I originally bought it and that 'cause me to run really rich under boost too. Are you running rich when WOT or even at idle and cruising speed?

When my mass was bad, it caused me to burn really rich all the time. I found out that my mass got wet and messed things up. Once I changed out the mass, it ran much better.

Hacking up the mass won't affect as severly in my case but, I am not sure about the OP's situation.

 

[cbrue122]

Engine coolant temperature sensor is another thing to check. If that sensor is bad it will make it run rich and will throw a CEL as well. I also found that the off-brand sensor does not get the job done; make sure it is the Mitsubishi brand.

 

[Infiltrate2000]

I changed the Mas already. Same problem. As for the plugs, all cylinder is running rich. Every plug is black. Turbo has barley any play, boost fine to stock level. As for the coolant sensor, i hooked up a data logger and it was giving me a reading of 209 degrees after running the car. My guess it is working, since the tempeature is high. I read that when temperature is low, the computer adds more fuel. But i am getting a reading. I have no CEL.

Also put a gauge, my fuel pressure is fine. Maybe 1psi above stock. But its nothing major. The poster who suggested fuel return line, thats something i was going to look into next. The fuel feed and return is the only thing i have not checked. Maybe a bad fuel filter can cause this? I know the hoses for the fuel return is fine, i will have to check the hard line. Please add more suggestions. I have tried so many thing and still no resolution.

Maybe i have a bad computer? I mean the computer threw cel codes before, and i get no smell but i don't know what else can cause the car to run this rich.

 

[c4uldr0n]

maybe too simple but have you tried unplugging your battery for a couple minutes to see if a reset helped?

 

[Splitpi]

fpr on the way out? What is the base pressure?

 

[Infiltrate2000]

43.5psi with vacum connected. Reset the computer many times too. I am really stumbled here.

 

[spyderturbo007]

43.5psi with vacum connected

Are you sure you don't mean that it was 43.5psi with the vacuum disconnected? You should check the FP with the vacuum line off, not on.

 

[Infiltrate2000]

Are you sure you don't mean that it was 43.5psi with the vacuum disconnected? You should check the FP with the vacuum line off, not on.

yes sorry. With it disconnected it was around 43-44. With it connected it was 35-36. The strange thing is, i taught with it connected it suppose to drop below 35 psi?

 

[Infiltrate2000]

Just want to add. I had the car parked for two hours. It around high 78-80 degrees today. I parked the car from 5:45 to 8. I just logged the intake temperature and its 105*F. I think this is very hot for the car just sitting. I will try and make a run tomorrow and see how hot it gets.

 

[hopwoodp]

Just want to add. I had the car parked for two hours. It around high 78-80 degrees today. I parked the car from 5:45 to 8. I just logged the intake temperature and its 105*F. I think this is very hot for the car just sitting. I will try and make a run tomorrow and see how hot it gets.

How long did it read like that? Also, what was the temp while driving at higher speed?

 

[Infiltrate2000]

May have found the problem. I took the heatshield off today. And behold, right above one of the stud, on the gasket there is a black carbon buildup. Only that one section. I looked at it, and it just doesnt seal. That part does not touch the gasket, every other thing does. I am guessing the manifold is warped there? Going to buy another gasket and replace the manifold too. I see all these part store only stock the paper looking gasket, not the metal one, do they work?

I hope this is my problem, i somehow dont think it is. The leak looks very small, because that little piece just doesnt seal. And the turbo spool perfect, no strain like if there was a major exhaust leak. Wish me luck.

 

[hopwoodp]

May have found the problem. I took the heatshield off today. And behold, right above one of the stud, on the gasket there is a black carbon buildup. Only that one section. I looked at it, and it just doesnt seal. That part does not touch the gasket, every other thing does. I am guessing the manifold is warped there? Going to buy another gasket and replace the manifold too. I see all these part store only stock the paper looking gasket, not the metal one, do they work?

I hope this is my problem, i somehow dont think it is. The leak looks very small, because that little piece just doesnt seal. And the turbo spool perfect, no strain like if there was a major exhaust leak. Wish me luck.

Get a metal gasket. Preferably the 4 layer one. When you change the manifold, clean all carbon buildup from the head (where the exhaust manifold mounts).

 

[Infiltrate2000]

Update-
Replaced exhaust manifold gasket. Car still runs rich. When start up, pure black comes out. It sticks on the ground, unburned fuel. I just got p0125 cel code, which people said is oxygen sensor. My oxygen sensor is brand new and has less than 2000 miles on it. I will swap out another one and see. I have no idea why the car is running so rich.

 

[hopwoodp]

Check your mass airflow sensor.

 

[Splitpi]

p0125 is Insufficient Coolant Temperature for Closed Loop Fuel Control, Meaning your car hasn't warmed up enought to be in closed loop (which the ECU is in). So your ECU is thinking it is running very lean and so throwing tons of fuel at it. I would think then it is an issue with either O2 sensor. Is the rear O2 connected?

Also consider replacing the ECU Coolant Temp Sender near the thermostat. Its a $20 part. Replace it, clear the code then let us know if the code returns. Still though it may or may not explain the pig rich fuel issue.

 

[Infiltrate2000]

p0125 is Insufficient Coolant Temperature for Closed Loop Fuel Control, Meaning your car hasn't warmed up enought to be in closed loop (which the ECU is in). So your ECU is thinking it is running very lean and so throwing tons of fuel at it. I would think then it is an issue with either O2 sensor. Is the rear O2 connected?

Also consider replacing the ECU Coolant Temp Sender near the thermostat. Its a $20 part. Replace it, clear the code then let us know if the code returns. Still though it may or may not explain the pig rich fuel issue.

The front 02 sensor is brand new. . Its was a denso unit. OE fit. I have a spare that i can use and see if it clears the code.

The engine coolant temperature sensor is what i was reading up on. It seems to be working fine because when i use the datalogger, it gives me an average reading when the car is driving around 180-210 * F. Its a cheap part, so i guess i can replace it.