Autozone did a computer read and noted "random" misfires, or something
to that effect. I was struck by the word "random." It sounded as if
the problem could not then be wires or plugs, as those would create
problems with specific cylinders. (I hope it is not these as the car
is now having multiple serious problems, including a rear main seal
leak, and I am reluctant to spend the $500 the dealer tells me will
be necessary to do the plugs and wires. No local mechanics will even
attempt to do this work.)
What would be the likely cause of these misfirings, if not plugs
or wires? If necessary, I will have the computer read done again and
note specific codes and post them here.
Help much appreciated!
When I see "random misfire" codes I think of fuel or fuel delivery, although
any part of the ignition that is common to many or all cylinders can be to
blame. Doesn't the '01 Caddy have individual coils for each cylinder? If so,
rule out ignition almost altogether.
The cheap and easy approach is to start with a bottle of injector cleaner
and a bottle of Dri-Gas in the tank. It will take a hundred miles or more of
driving for the injector cleaner to do its thing, but that code is fairly
heavily "damped" anyway; it takes a while to decide to come in and takes a
while to clear on its own.
As 'hls' says, it could be vacuum leaks, too. I just like to start with the
easiest when it is non-emergency.
This is the year 2006, not 1965. This is a Northstar, not a
K-car. The dealership routinely makes 100% markup on
many, many items. You figure it out.
By the way, to the original poster....I don't believe that
you have spark plug wires on this year of Northstar
anyway. This year should have the coil pack cartridge
with spark plug boots, but that's about it.
Times have changed. Plugs run from $2 to $10. Wires can be $10 each.
Given the age and miles on the car, it would be about time to replace them
if they have not been already. I did my 01 LeSabre just a couple of months
ago because of mis-fires. It was a lot less than $500 though, more like
$120, IIRC at a local shop.
A while back I compiled (in another forum) a list of some of the things that
have changed since carburetors roamed the roads. I forget most - many were
contributed by others - but some are:
*the radiator could be topped off with a garden hose
*to tell if the alternator was working, unfasten one battery terminal to see
if the engine dies
*the radiator overflow just spilled on the road
*the points should be filed or replaced at least once a year
*the alternator could be run at full rated output all day
*spark plug gap could be set with a gap tool
The problem has to be diagnosed correctly, not stabbed at with a bunch of
WAG's. The OBDII system has a ton of information in it to diagnose the
problem. Were there any other codes besides the random misfires? Any other
codes could be the cause of the misfires. Take it to the dealer and pay him
to diagnose the problem. Cars today are computers and cannot be fixed by
randomly throwing parts at them like the old days...
Good advice, but typically "random misfire" codes show up all on their
lonesome. All the system knows is that the engine is running unevenly as
determined by fluctuating time between equivalent angle sensor intervals.
It's kind of the automotive equivalent of "my tummy hurts." Could be
anything from bad gas to fouled injectors to neglected PCV. I pride myself
on my troubleshooting skills (on the electronic side I do that for a
living), but the best that can be done for this is to make everything right
and then see what affects the engine after that.
No, most non-Cadillac techs want nothing to do with the
Northstar engine. Can't say that I blame them....it's certainly
not hard to work on once you know your way around them
and you have the proper tools, but they can be quite daunting
if you've never worked on one.
It's quite rare that the rear main seal leaks....and I'd like to
know how the dealership can pinpoint the leak to the rear
main seal without pulling transmission out. It's far more
likely that you have a case half seal leaking, or the oil
pan gasket is leaking. Either way, it's a very expensive and
labour intensive job.
Did the dealership diagnose the "random misfire" problem
and then tell you to replace the plugs and wires, or did
you just take the "very little" amount of information you
got from Autozone and ask the dealership how much to
replace the wires and plugs? If you did the second, I
would reconsider and have the dealership perform some
proper diagnostics. I can tell you what we do a lot of on
these engines. We put a lot of crank position sensors
in them (there are two in these engines).
Thanks to all of you for your information and especially
*for the time you all spent* to have such a spirited and
This vehicle will probably go back to the dealer. I got the
suggestion of bad plugs and/or wires from the Autozone gal when I
told her that I had never had the plugs/wires changed in
about 120K miles (I bought the car with 26K on it and I
assume the plugs/wires were not changed in that interval.
Note also that *nothing* has been done to this car since
I have owned it, short of normal tire and brake maintenance
and oil changes.) I hoped to find something that could be done
locally since the dealer is about 45 minutes drive.
The dealer had recently diagnosed the rear main seal
problem, but the misfire problem is new. The $500 ballpark
estimate for plugs/wires was based on a "what if" question.
We did not explore other possibilities when I talked to the
Every local guy I spoke with refused to work on the
plugs due to their inaccessibility. I cannot evaluate why they
have said this, except to take note of your comments here.
Anyway I will go back to Autozone and write down the
details of the diagnosis and post them here to see if that
helps point in the right direction before I do anything else.
I'll be back soon with this info.
The engine was stumbling so badly I would have to guess
that more than one cylinder was involved.
Once again "thank you!"
That's funny....the dealership should have known these
engines don't have wires.
Hmmmm.....they aren't that hard to change on these engines.
The front four are a snap, the rear ones are more difficult
only because of the air injection plumbing that has to be
removed before the rear coil pack cartridge can be removed.
But still well within the realm of possibility for even the
By the way, the proper response to any suggestion made
by someone like the staff at a store like Autozone when it
comes to driveability issues would be a polite nod of the
head, and then quickly forget anything they might suggest
and have it diagnosed properly.
BTW as for crank position sensors, these were changed twice.
When they were bad, the problem was sudden stalls, and slightly
slow starting of the Northstar, nothing like this. Also, the second
time the dealer told me they were redesigned.
If it appears I am contradicting myself about *nothing* ever
being done, I meant no regular maintenance on things like
plugs or other "tuneup"-type items.
If you are at 146k miles on the original plugs and wires then it is
surely time to change them and they are the most likely cause of
misfires. Sure there are other possibilities, but that is the place to
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