Hi all,
The engine light on my 2002 honda accord just went on. I took it to
the shop they replaced the spark plug but also said the compression
was low on cylinder 1. They said it was at 100lbs and should be around
150 lbs. They said the check engine light might come back on for that.
After two starts, the check engine light is back on. How concerned
should I be? It misses while idle and when it goes into the 65-70 mph
range. Whats the problem? Maybe a head gasket issue? Is it safe to
drive? How much should it cost to get fixed.. I've also noticed
slightly worse gas milage. Should that be a concern? The missing
started after my last oil change, and 3 weeks later, the check engine
light came on. Did the person who did my oil change potentially mess
up my car?

Forgot to mention, car has 117k miles on it.

Amanda wrote:

With 100 lb compression, the cylinder still should fire.

Low compression can indicate the condition of valves and rings primarily.

If compression is low and introduction of some oil into that cylinder
results in a better reading, worn or broken ring(s) are indicated. If no
change, a valve may be in the process of being burned.

Additionally, low compression can indicate a head gasket problem but
usually this is accompanied by other symptoms such as coolant in the
exhaust, oil in the coolant etc. Many times, low compression will occur
in adjoining cylinders.

If the car has been maintained properly, 117K (as indicated in your
follow up post) is way too early for serious problems of this nature but
I'm sure that others here will offer good advice.

JT

The check engine light should have a number, something P-0301. What
code(s) do you have?

Spark misses may be caused by a bad spark plug wire or plugs among
other things (EGR system). In this case you already have new plugs and
maybe should also check/replace wires if not already (but they should
still be good at 117K miles).

Low compression is most likely piston ring wear or valve sealing
problem. It may be as simple as adjusting valve clearances but can get
as involved as replacing piston rings for example.

Besides the simple oil trick mentioned (if squirting oil seals then
you know it's the piston rings), you may want to consider a "leak-down
test".

http://en.wikipedia.org/wiki/Leak-down_tester



On Jul 30, 3:44*pm, Amanda <amanda.sch... (AT) gmail (DOT) com> wrote:

Don't know about the oil change causal factor, at least not as obvious
as doing a timing belt or tune-up for example. But where was it done,
Honda dealer? What type of oil/filter?


On Jul 30, 3:44*pm, Amanda <amanda.sch... (AT) gmail (DOT) com> wrote:
The missing

Amanda wrote:
three potential causes:

1. burnt valve. expensive.
2. blown gasket. expensive, but easy to differentiate from other symptoms.
3. worn or cracked rings. expensive.

bottom line, an oil test will tell you if it's a ring or valve/gasket,
and a look in the radiator when running will tell you if it's the gasket.

from here, you have two choices

1. get the repair work done. many labor hours and thus a huge cost.
four digits.

2. replace the engine with a used jdm import. three digits typically.

if it were my car, i'd look into the latter option. not because the old
engine can't be repaired, but because cheap and available low mileage
import engines make so much more sense.