[V8] Engine Still Not Running Smoothly ...

urq urq at pacbell.net
Sat Nov 7 18:01:11 PST 2009

When I got the engine back together I left the big cover that holds the air
filter in place off (the air filter was installed).  The engine does seem to
run more smoothly 
 perhaps due to the fact I had to mess with ¾ of the
spark plug wires when I pulled the distributor.  I’m still thinking the
engine is a bit down on power compared to the other car 
 but perhaps this
is due to the cams from the automatic engine 


As those who have pulled this cover know, the engine intake sounds are much
more audible with the cover removed.  One thing I noticed was that I could
hear a variable hissing at idle.  I’m thinking it is the ISV, and perhaps a
sticky ISV 
 but it did seem to cause a bit of rough running.  I
disconnected the ISV and kept the engine running by cracking the throttle a
bit, no hissing.  


I’m going to use the carb cleaner method to see if the ISV is sticky, but if
any others out there have had to deal with similar issues and have something
to share I’ll appreciate hearing from you!


Steve Buchholz



 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
 then I thought to fire up #344 in the adjoining bay 
 smooth as


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
 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

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