Amanda wrote:
> 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?


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