black smoke, black plugs need help please
- Thread starter RED88XJ
- Start date
MudderChuck
New member
1045850
Fuel rail pressure test, pressure regulator (stuck closed or blocked), maybe a stuck fuel shutoff (stuck open). Are ALL the plugs black with soot? Make sure the EGR valve isn´t stuck open (won´t idle). The EGR doesn´t work often at idle, but can make you run a little rich at speed. Vacumn test at the intake manifold (between 10 and 15 inches of vacumn). Sucking air somewhere in the exhaust manifold will mess with the 02 sensor (exhaust manifold leaks sometimes suck air due to a venturi effect) as will a vacumn leak (usually resulting in a high idle). Are there bubbles or foam in the coolant sytem at operating temp.? You may have crossed up the vacumn lines and are getting conflicting signals to your computer. MAP sensor will mess with the fuel metering as will the 02 sensor. A few ideas.[addsig]
Fuel rail pressure test, pressure regulator (stuck closed or blocked), maybe a stuck fuel shutoff (stuck open). Are ALL the plugs black with soot? Make sure the EGR valve isn´t stuck open (won´t idle). The EGR doesn´t work often at idle, but can make you run a little rich at speed. Vacumn test at the intake manifold (between 10 and 15 inches of vacumn). Sucking air somewhere in the exhaust manifold will mess with the 02 sensor (exhaust manifold leaks sometimes suck air due to a venturi effect) as will a vacumn leak (usually resulting in a high idle). Are there bubbles or foam in the coolant sytem at operating temp.? You may have crossed up the vacumn lines and are getting conflicting signals to your computer. MAP sensor will mess with the fuel metering as will the 02 sensor. A few ideas.[addsig]
MudderChuck
New member
1045866
A compression test might be helpful, should tell you if you have a valve hanging open or ring and cylinder damage. Make sure all the rockers wiggle a little, when each cylinder is at the top of the compression stroke. You may have set the lash a little to tight.[addsig]
A compression test might be helpful, should tell you if you have a valve hanging open or ring and cylinder damage. Make sure all the rockers wiggle a little, when each cylinder is at the top of the compression stroke. You may have set the lash a little to tight.[addsig]
