[V8] Engine Still Not Running Smoothly ...

[k1drbar]

. in preparation for the smog inspection I went through and did a
replacement of the spark plugs, dizzy caps and rotors in #2 . 

 

The "new" engine I installed a few years ago has always run a bit rough for
a V8 IMO.  I had imagined that there was something wrong inside a combustion
chamber or some such . well, since I had all the spark plugs out I did a
compression check . the first measurement on #4 was ~120PSI, considerably
lower than the ~160PSI I saw on the other cylinders . but then since that
was the first pot I tested I decided to go back and check again later .
compression was now up with the rest of them.  I verified that each cylinder
was firing by pulling the plug wires off, each one seemed to have a
consistent effect on the idle speed and smoothness of the engine.  I started
to convince myself that the engine was running smoother with the new bits
installed . then I thought to fire up #344 in the adjoining bay . smooth as
silk . 

 

The engine in #2 is an automatic variant, but I can't imagine that would
make a difference in smoothness of the engine.  I wouldn't imagine bolting a
flywheel on the crank would have imbalanced it in any way (it was a brand
new flywheel).  This engine also seems to be down on power compared to #344.
I thought I'd toss this out to see if there are any hypotheses out there on
what may be going on.  The ECU shows no fault codes.  I've got the set of
injectors sitting on the PT in the garage . I may try running them to see if
it makes a difference.  

 

While I found some plugs to be in better condition than others, the exhaust
does not have a strong hydrocarbon smell when the engine is warmed up and
running . in fact it seemed clean enough that the car would likely have
passed the test as is . I just like to have a bit of margin . and the
ignition parts are the ones that came with the engine . in fact I had to
break the old rotors off with a vise grip . 

 

Steve Buchholz