Spark Plugs (pics)

[supercrackerbox]

I need your ideas on what happened to my spark plugs here. These are NGK GR4s with about 6-7K on them. Symptoms are a rough idle, lack of top end power, and random stumbles throughout the RPM band. Please note the tiny chunk of crap hanging off the end of #2. It's very solid, feels like metal.

Plug #1



Plug #2





Plug #3



Plug #4



With the new plugs, the car also got a new thermostat due to a code 17, all vacuum lines were inspected. New cap and rotor were installed when the NGKs went in, wires seem to be okay. Still, the problems persist.

Thoughts?

[Turbodave]

There's a pretty big difference between 1/2 and 3/4 plugs. Are the compression numbers consistant across the board?

[supercrackerbox]

Don't know, I need to find my compression tester. This is the engine that I had in my CSXT (now in my Daytona). The cylinder head had just been redone when I bought that car, and was stored in favor of the ported one that is now on my Charger, and went back on this engine when it went into the Daytona (keeping this straight? lol). The bottom end was fully rebuilt for the CSXT, and torn down again at around 5K due to a collapsed ring on #1. I think it has about 25K on it now, so yeah a compression check probably would be in order. No coolant or oil loss, and only a very minor trace of blowby through the oil fill.

[Turbodave]

Just curious if there is maybe a bad gasket between #1 and #2? could explain the deposit on the plug, the poor performance, and why those two cylinders would look richer, and the others look leaner due to the computer trying to compensate for incomplete cobustion on #1 and #2.

Just a theory, but doing a compression test should prove me wrong or right.

[supercrackerbox]

Thought crossed my mind too, but with no coolant/oil loss or mix and no erratic temperatures, I kinda ruled it out. But a small gap just between #1 and #2 would make sense. I'll try to do a compression test in the next day or two, or at least by this weekend.

Let's see, today is Wednesday, so by Saturday I'll have another 180 miles on it. Gulp. But off to work now.

[supercrackerbox]

L-R 120 30 120 120

Yeah, this is worse than I thought.

[moparzrule]

OK so number 2 is dead, broken piston probably. But 3-4 look really lean. I'd check your injector wiring harness and/or check for clogged injectors.
If number 1 didn't look like a perfectly normal plug I'd say check the FPR. But I would still make sure your fuel pressure is good. But I suppose since number one is the first injector to get fuel, it still is getting the most fuel even with a weak fuel pump.
What fuel pump do you have? When was the last time the filter was changed?

[supercrackerbox]

Fuel pump is a Walbro 190, and I have a Wix fuel filter, both were installed at the end of October.

I don't know if I have any extra fuel injectors I can swap in, I'll have to look.

[Turbodave]

That sucks Adam, sounds like a cracked piston. My van had similar numbers when the #1 piston cracked on it. I drove the van like that for a few months anyhow, never used any oil or smoked or anything, just a rough idle and a little down on power.

[supercrackerbox]

Well I've already been driving it a few weeks at least since the problem showed up, and don't have much choice but to keep driving it. Gotta get to work if it kills me. Haven't missed a day yet, and can't until June if I wanna be able to go to SDAC.

A few other guys here think I might have burnt a valve, is that a possibility? I need to find someone with a leakdown tester and learn how to use it. If it's something relatively simple, I'll fix it, but otherwise I think I'm going to just re-double my efforts on the Charger and drive the Daytona til she blows up, and haul it to the scrap yard. Charger probably could have been done weeks ago, but I've been spending a lot of time helping a few other guys with their engine swaps.

[moparzrule]

Does your head have non turbo valves?
It's possible.

[turbovanman²]

Hate to say it but you've melted a piston, those chunks on the plug are molten aluminium, been there, done that. Cracked pistons usually have around 90 psi compression, holed pistons much less.

[supercrackerbox]

Just seems odd to me that I wouldn't be burning a lot of oil with a broken piston. But I'll find out for sure in a day or two. Gonna crank it to TDC and put air to it and see exactly where it's coming out. I know for sure it's got the turbo valves, this is the head that came factory on my CSXT.

Now, tell me if this makes sense. Whatever the reason, this engine has a dead hole. Being as such, the air fuel mix can't be burning properly in that hole, and would then be dumping a fair amount of raw fuel out the exhaust. Would the O2 sensor be picking up on this and trying to cut the fuel back, and maybe that's why the other two plugs look so lean? Or am I not thinking straight on this?

[moparzrule]

Does your oil smell like gas?

[supercrackerbox]

Negative.

[86Shelby]

Would the O2 sensor be picking up on this and trying to cut the fuel back, and maybe that's why the other two plugs look so lean?

The O2 sensor picks up on the oxygen in the exhaust, not the fuel. Misfires will generally throw a lot of unused oxygen into the exhaust and cause the system to run richer to compensate.

[supercrackerbox]

[turbovanman²]

Yes, the ox picks up all the oxygen and tries to lean it out as it see's a rich mixture.

[Turbodave]

Yes, the ox picks up all the oxygen and tries to lean it out as it see's a rich mixture.

To Ray's point though, wouldn't an unburnt mixture have more oxygen in it? That would tell the o2 sensor the mixture is to lean which in turn would result in the computer richening the mixture? That makes sense for a misfire at least.

But in Adam's case, the cylinder is firing, so we will assume the charge is probably being ignited. Due to the low compression the volume of oxygen in the cylinder is less than normal, but the injector still adds the same amount of fuel so the result is a rich mixture on that cylinder. When this is read by the 02 the result is a rich mixture to which the computer would compensate by leaning things out. It think this is what Simon is trying to say.

[turbovanman²]

To Ray's point though, wouldn't an unburnt mixture have more oxygen in it? That would tell the o2 sensor the mixture is to lean which in turn would result in the computer richening the mixture? That makes sense for a misfire at least.

But in Adam's case, the cylinder is firing, so we will assume the charge is probably being ignited. Due to the low compression the volume of oxygen in the cylinder is less than normal, but the injector still adds the same amount of fuel so the result is a rich mixture on that cylinder. When this is read by the 02 the result is a rich mixture to which the computer would compensate by leaning things out. It think this is what Simon is trying to say.

Yes, the bad cylinder is full of unburnt fuel hence tons of oxgyen, the sensor pics this up as being rich so the computer compensates by leaning out the mixture. My Emissions theory is a bit rusty so I could be backwards on rich/lean operation of the ox sensor.