Terrible Looking Spark Plug. Pictures*

[1994lt1]

I changed my spark plugs the other day and all of them were spotless besides the last one on the passenger side. It seems to have a kind of sludge on it that at the time smelled of gas. I changed the plugs about 6 months before this so it hasnt taken long to get this bad. After I saw this plug I ran some Techron fuel treatment in it and I fouled an o2 sensor on that side... I think thats a good sign but what does this look like to you.

http://i39.tinypic.com/e05utu.jpg


http://i44.tinypic.com/v43wiw.jpg


http://i44.tinypic.com/10ol4xl.jpg

What are your thoughts?

[GP99GT]

does the car smoke at all? deposits like that are usually a sign of oil burning

[1994lt1]

No the car doesnt burn at all. I did a compression test tonight and all was fine. I think I'm going to let it go for now. I cant get into valve seals at this point its just bad timing.

[HardcoreZ28]

I second that it's oil. Besides a compression test I'd run a leakdown if I were you.

[JL8Jeff]

I think that last cylinder gets all the stuff that gets into the manifold. Check your pcv to see if it's sucking in any oil through the line. Also check the crank vent line that goes in near the throttle body. You might also have a plug wire getting weak back there. Check inside the throttle body to see if there is any oily buildup. I would expect that to affect more than 1 cyl though. How many miles on the engine and have you ever replaced the plug wires?

[LTb1ow]

I think it would have been both back cylinders,and most times they are running a tad lean. But yea, def check the wires, stock routing is horrible.

[sweetbmxrider]

what was the gap on that plug?

[1994lt1]

I changed the wires on the car about 6 months ago. The car has just over 100,000 miles on it. How would I check to see if the spark is weak?

[sweetbmxrider]

gap??

[LTb1ow]

I changed the wires on the car about 6 months ago. The car has just over 100,000 miles on it. How would I check to see if the spark is weak?

Well, you could borrow the tool used for it, not sure what its called, basically it goes in series with the plug and you can adjust the gap to see where the spark fails at.

Or just go shotgun method and replace the coil. :lol:

But yea, what was your gap? Stock is hugggee.

[sweetbmxrider]

its not like you are measuring the spark though....

it really looks like oil contamination though, i was just curious what the gap was since it smelled of gas. could also have corrosion in the opti or something though.

[1994lt1]

I am unsure of the gap sorry not to respond. I set it to stock when I changed them though.

[JL8Jeff]

I wonder if that cyl is sucking oil from around the intake gasket, the LT1's do have an intake gasket leak problem. Check those intake bolts, at least around that cyl.

[sweetbmxrider]

thats kinda what i was thinking jeff. the egr sits too close to the intake and bakes the rtv. then you leak earl

[1994lt1]

Ok so heres another strange possibly related problem. Tonight I noticed that when the car is in overdrive (about 50 mph and 1500 rpm) and I ease onto the gas without making it downshift, the car jerks like crazy while trying to accelerate. I didnt notice it as much at lower speeds but I did terribly when its in overdrive. Im thinking maybe because the engine is being strained and thats when its most likely to occur? Anyway there are now SES codes or anything and I am lost. I am getting really fed up at this point. Any ideas?

[LTb1ow]

Strange, no codes?

Could be spark falling apart, but usually when the coil dies its at higher RPMs that the symptoms show. Were you in [D] or D?

[1994lt1]

No codes what so ever. I am IN overdrive when this occurs.

[JL8Jeff]

You may want to check the resistance on that plug wire to see if it's damaged internally. Try moving the spark plugs around as well to see if the problem stays in that cylinder or goes with the plug. The plug might be damaged and not sparking strong enough. It sounds like you were running on 7 cylinders when it started jerking.

[LTb1ow]

Are you running stock manifolds and what not?

Idk where you are, but I have a few stock wire sets laying around if you need a wire or two.

[1994lt1]

Yes I am running stock manifolds. I pulled the plug out of cylinder 8 with 250 miles on it and it smelled of gas and only had minor to minimal sludge on it. I think Im going to test that wire now.