Is it a bad valve, valve seat, or valve guide?
It's a 95 5.7L in a Silverado.
The problem. I put new cap, rotor, plug wires, plugs. I drove it for about 40 miles or so and decided to pull the plugs to see if there was any detonation or flooding of cylinders. Before I explain the problem I will let you know the firing order so I can say what I need to say and it'll make a little more sense.
Drivers side (Left Bank) firing order: 1, 3, 5, 7
Passenger side (Right Bank) order: 2, 4, 6, 8
Okay, I pulled the driver's side plugs first and there seemed like there was carbon on cylinder 1 and a little drop of gas on it as well. So I am thinking that this is just because I'm running a little rich. I thought this from the beginning anyway. Thought the new ignition over haul would have helped. I pulled the other three and it was fine. I found this a little fishy since it's a TBI fuel setup and thought that since all the cylinders *should* be getting the same amount of fuel.
I pulled the passenger side (right bank) plugs and ALL of them had significant carbon build up on them. No oil, just carbon. All except for number 8 (closest to firewall) When I pulled that one it had the carbon build up but it also had oil on the part of plug closes to the plug wire, not actually on the threads.
Does anyone know what is going on? The truck only has 113,000 miles but it did set up for four years before I bought it. Which I won't buy a truck that sit's up for that long again. Always have all kinds of problems. New parts include fuel pump and fuel filter plus the new ignition. Fuel pressure is within specs. 11 psi. Book says for it to be 9-13. If any other information is needed you can email me from my profile. Thanks for any/all help.
Oh, and it does not smoke. None whatsoever.
Oh yeah, one more thing. The O2 sensor is BEFORE the catalytic converter but the catalytic converter has been removed...I know, I'm going to put another one as soon as I can afford it.
Don't know if this will make much difference either but the ignition coil (coming from distributor was not bolted down....
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Tags: 7l, catalytic converter, detonation, firing order, fuel filter, fuel pressure, fuel pump, little fishy, number 8, o2 sensor, one more thing, plug wires, psi, rotor, silverado, threads
February 3rd, 2010 at 11:52 pm
I would say you are probably burning the old fuel and once it is entirely cleaned from the system it will be alright. You might put some B-12 injector cleaner in the next few tanks to help.
February 3rd, 2010 at 11:52 pm
I would recommend replacing the PCV valve, as well as the oxygen sensor that is up front, in the exhaust manifold. The problems you detail don’t really add up to make any sense to me, either, but my guess would be the PCV valve is pulling too much oil and the O2 sensor is slow, a common GM problem. I hope this helps. Another really common problem is a leaking base gasket for the TBI unit (vacuum leakage).
February 3rd, 2010 at 11:52 pm
as i read what you have said,to me it sounds as if the oil is on the ceramic portion above the thread if so then it is probley an oil leak from above the plug.!
February 3rd, 2010 at 11:52 pm
Sounds like it had some bad fuel, when an engine sits for years it can also slough carbon from the valves and pistons, it will take a few hundred miles before you can actually read the plugs.