2001 Sonata 4 cylinder - Two questions

I purchased my 2001 Sonata used from the original owner. I now have just
over 10K miles on the car and it has developed an erratic engine miss ( 90%
of time missing-10% of time seems OK)- This engine starts fine and
accelerates OK. The miss is most noticeable at idle or if just cruising at
very low power requirements. At idle the miss is occasionally severe. I'm
not getting a check engine light despite significant bucking and stumbling
of the engine. Does this in both humid and dry conditions. I've had my local
garage check the plugs / wires / injectors without improvement. They feel it
may be the coils. They'd like to see the computer codes but I'm not getting
the check engine light.
Questions:
1. Is it necessary to replace both ignition coils at the same time- or can I
just try swapping one at a time ?

2. Will this replacement be covered under warranty if I return the car to
the dealer. I've gotten conflicting reports as to what warranty coverage is
transferable to a second owner. Anybody know for sure what (if any) warranty
coverage is transferable ?

Thanks,
Jon Harris

 

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Jon,

If you are in the U.S., the 6 year/60,000 mile warranty is
transferable.

Depending on just how the "miss" feels, it might not be electrical at
all. Could be a fuel/air problem -- a clogged filter, perhaps, or
possibly a clogged air filter. Less likely, a problem with other parts
of the air intake system?

BTW, just because the check engine light isn't coming on doesn't mean
there are no codes stored. If it were my car I would get the codes
read out. In our area Auto Zone parts stores will to that for free.
Checker stores will loan you the code reader for free. Our dealer wants
$85.00 for the same readout.

If you do try the coils I would do one at a time -- it's extremely
unlikely that both would be bad (actually, it's a very long shot that
*either* of them are bad).

Good luck!

Harry

If the car only has 10K miles on it none of the "usual suspects" should
be presenting, however. How many miles does the odometer have on it?