Misfire 4
#1
Misfire 4
I have a 06 ss Monte Carlo 5.3 with about 90k miles I'm getting a misfire cylinder 4. Good plugs, coils, plug wires, and good injectors. So what should I check next? My engine light flashes when I accelerate it smokes white at idle after about 10 minutes of driving. Hoping not a blown gasket.
#2
Join Date: Apr 2010
Location: Mentor, Ohio
Posts: 12,236
White smoke is water/anti-freeze burning off. I would advise taking the plug out of the #4 cylinder, see what it looks like. It may tell you a big clue to what's going on. You can compare it with other plugs, see how they all look. You can also conduct a compressing test and see if a cylinder is loosing compression.
But the smoke from the exhaust is not very promising.
But the smoke from the exhaust is not very promising.
#3
I have a 06 ss Monte Carlo 5.3 with about 90k miles I'm getting a misfire cylinder 4. Good plugs, coils, plug wires, and good injectors. So what should I check next? My engine light flashes when I accelerate it smokes white at idle after about 10 minutes of driving. Hoping not a blown gasket.
Are you using/loseing Anti-Freeze? Does the Motor run hot? Is the Number 4 plug discolored when you removed it? Does it smell other than of gasoline?
These are all signs of a possible leak/headgasket.... The white smoke after idleing for 10 minutes does the exhaust have a "sweet" smell to it?
If you pull off the oil fill cap...does it have a milk shake color around the edges/or inside the valve cover? Is it low on oil? or overfull? Is there a milk shake color on the dipstick?
I would also recommend do a pressure test on the cooling system.
I would do a cylinder leak down test on the #4 cylinder.
I do know in 2003 and 2004 Chevrolet used a substandard heads on the 5.3's .... They were known to develop small cracks in the top of the head
near/around the valve guides... Thus causeing a coolant leak ... and cylinder failures.
I'm not saying you have a cracked head... But anything is possible.
I hope this helps...Please get back with us and let us know what you have found out...and or how you fixed it.
Thanks for joining the MCF Family.
#5
There is a problem on the LS4 related to oil blow-by caused by the DOD system. Are you burning any oil? Also, here is a site with some GREAT info.
LS4 FAQs - LS4 Store
LS4 FAQs - LS4 Store
#7
So I just found time to take it apart. I got to taking off the manifold all ports are dry except cylinder 4 that was misfiring was filled with gas any suggestions
#9
Join Date: Apr 2010
Location: Mentor, Ohio
Posts: 12,236
Possibly a failed injector leaking gas in the cylinder. Or a spark plug not firing or firing with weak spark (could be plug, wire or coil). My two best logical guesses.
#10
New plugs, new wires, coils good, injectors good