Would like some input on options to keep this car alive but I have to try and start from the beginning, it's quite a story. Family members' Honda Odyssey 2004, been on the road for quite some time. Has had catalytic converters replaced 3 separate times over the years. This year it was replaced again. And needs to pass the emissions test. Codes keep coming up and it's been with a mechanic hunting issues with a shotgun. The spark plugs been replaced along with coils, IAC valve, Evap solenoid valves and a misfire showed up. Intermittent. Not constant but it trips more codes. It was serviced for oil change and the lube shop stripped the plug so it leaks a ton of oil constantly. So much in fact it was accidentally driven with low oil and started smoking. oil was refilled and it ran just fine with some blue puffs of smoke for a day or so. after that the blue exhaust went away. Ditched that mechanic and went to another who said the compression in the cylinders are low. No word of doing a wet test. is this engine toast? Is there a way to bring it back? Is it possible that carbon build up on the valves may be the cause of all this? Or are the pistons rings gone? Seems like a long issue that's been compounding over time. No signs of blown head gasket.
It was serviced for oil change and the lube shop stripped the plug so it leaks a ton of oil constantly. So much in fact it was accidentally driven with low oil and started smoking.
Very likely there's your problem. We recommend people avoid quick lube shops since that kind of incompetence is all too common at those joints.
is this engine toast?
Very likely. Do a wet versus dry compression test, or better yet a leakdown test, to determine where the compression is being lost.
Is there a way to bring it back?
Rebuild the engine.
Is it possible that carbon build up on the valves may be the cause of all this?
Not likely. You can use a borescope to get a look at the valves and the cylinders.
are the pistons rings gone?
Very likely.
No signs of blown head gasket.
Lost compression is a sign of a blown head gasket, but it would be highly unusual for it to affect all cylinders.
Very likely running the engine without enough oil damaged it internally. There may have been problems even before then. Catalytic converters don't fail that frequently unless the engine is blowing out unburned fuel through the exhaust or is burning oil. The cost of replacing or rebuilding the engine in a 21-year-old Odyssey, which is likely to blow out its transmission next, is going to exceed the value of the vehicle. You can do further checks as mentioned above but realistically it's time for a new car.
