So I went and pulled all the spark plugs. They were all pretty good except
for cylinder 8. That one was fairly gunked for a regular change interval,
but extremely gunked considering it only has 4000 miles on it.
be sure sparkplug and or sparkwire are good
...not fairly new...but working...fairly new does NOT always equal working
actually you haven't found the cause...you have found the effect. the effect
of missfire on No 8 it causing what you found
good luck with the cause
Is there any way for me to check this without replacing it? Buying another
spark plug is not a big deal, but buying a new wire is a waste of a lot of
money if I don't need it. Also, considering that the plugs only have 4000
miles on them, can I just change the one that was fouled?
If it is oil deposits on the plug, it may have a valve guide "floating" at that
cylinder, i.e. no longer attached to the head. This can be fatal. Do not drive
the car until someone pulls the left cam cover, sets no. 8 to top dead center
with the valves closed, pressurizes no. 8 to hold up the valves, and removes
both valve springs and seals from the guides for no. 8. With the air OFF, check
for excessive side play between valve and guide, and evidence that the guide
itself has been moving up and down in the head.
425 White Horse Pike
If the car has gone about 1000 miles with the miss and not died yet, could
this still be the issue? How soon can it kill? My dad says he only needs
about 1 more year out of the car or so (then it won't be junked, but we can
just park it. Once I'm out of college I'll be able to do all the things I've
planned on doing to it)
What do you think having someone do that cost me?
You mean, like, see no evil, hear no evil...
The fouled plug is the handwriting on the wall. Doing something about it now
may prevent a failure, or it may be too late already. If the guide is still
secure on the head, and is just passing too much oil down the valve, replace
the seals for those two valves (better yet all valves) and change the plug as
425 White Horse Pike
Pretty much. My family needs 3 cars, and the only reason the 380 hasn't been
replaced is because I want it. He only needs one more year from it because
he's waiting for the new vette, the new mustang, and to see what happens
with the GTO.
As far as the number of miles post-miss, I need to correct myself. It's been
about 300-400 miles (i wasn't here when it started, and I just figured by
how long its been going on that it had been 1000 miles, but it has actually
been 3 or 400)
Is this something I can check? I can do pretty much anything on the car, I
just am not good at diagnosing things from symptoms, and I don't have
Is this something I could do myself? On a scale of 1-10, with 1 being
changing the oil changing fuel injectors being a 4 and changing the rear
main seal being a 10, what would this be? How much would this cost at
Also, that test you said to have somebody do before driving it any more, if
I wanted to ask a shop how much they would charge to do it, what do I ask
for (i.e. what is that procedure called)? How much you think they would
charge to check it?
Thanks a lot,
The cause of the problem turned out not to be a real biggy. The lamba needed
to be adjusted (the little tool he used gave a reading of 2.5 and he
adjusted it to 1.5) and the cylinder 8 fuel injector gets clogged up by
something in the lines. The mechanic told me to flush it out and use some
I found why my 6.9 was running rough too, when I changed the plugs they all
smelled strongly of fuel, so I immediately pulled off the distributor cap,
and discovered the real problem - the contact on the rotor had fallen off -
its never been changed in its life. replaced it, now the engine even starts
on the FIRST rotation of cranking every time, basically 0.5 seconds after
turning the key to start :)
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