"Stephen Young1" wrote:
> shiden_kai wrote:
> > NickHanson wrote:
> >>I have a 1997 GMC pickup with the 5.7L V-8 Vortek
> engine. The problem
> >>I have is that it has a bad miss/shudder down the road
> and rough idle.
> >>I recently pulled all the plugs to check the condition
> and see if
> >>there was anything unusual. The spark plug on the #6
> cylinder is
> >>covered with carbon. I also noticed that I have been
> lossing a little
> >>bit of anti-freez, about a half gallon every few
> months. I think I
> >>may have a burned valve on the #6 cylinder?? Also
> maybe a leaky
> >>intake gasket possibly both on the front and rear.
> Any ifon that
> >>anybody may have would be great or any ideas as to
> weather my
> >>diagnosis is correct on the burned valve. Thank you
> very much
> > The first thing I would do is get the intake gasket
> replaced. Not
> > only do they leak antifreeze on these engines, but I've seen
> a number
> > of them get distorted and they will go out of shape and
> > a vacuum leak at a cylinder or two. The vacuum leak will be
> > the engine, so spraying stuff around the exterior of the
> intake will
> > not find the leak. Anyway, if you are using antifreeze, the
> > needs to be replaced. I'd do that first and then see how
> she runs,
> > she may smarten right up.
> > Ian
> While you have the intake manifold off, do a thorough cleaning
> of the EGR valve & passages -
> mine had 100% blocked passages which, when cleaned, smoothed
> the motor immensely.
Thanks for the suggestions. I will do the manifold gasket first and
do a good cleaning inside when I have apart. But I cant see that
causeing #6 spark plug to be covered with Carbon?? Maybe I am wrong
but I think there are further problems. Last night I unplugged my
mass airflow sensor and it did not take the roughness away but did
give me all my power back and improved my gas milage quite a bit too.
Anything else you guys can think of would be great!!
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