Oil disappearing...

I'd like to say hi as I am new to this forum.

My problem is kinda strange. I Last year about this time I started getting the check engine light but due to being unemployed I ignored it for about 2 months. Shortly after the engine started misfiring and that's when all hell broke loose.

First - I realized that the rubber air hose was almost completely in half, so I replaced it and the air filter (while I was at it).

Second - The misfire/check engine problem was not really going away and I realized that the oil was low and the valve cover gasket was leaking. So I replaced the VCG along with the spark plugs, wires, and coil packs.

Third - Check engine light went and misfire problem disappeared for about 1 month. But now I'm still losing oil at the rate of 1 quart per month (with high mileage oil), the check engine light is back on (Code: Warm-up Catalyst Below Threshold Bank 1), and it seems like it might be slightly misfiring on the highway at high speeds.

- I have a manual with 112000 miles.
- There is no oil on the ground nor is there any smoke coming out at any time. I have been watching it during cold start and intermittently while driving.
- Otherwise the car seems to be driving fine...

PLEASE ADVISE!!!

BTW, I checked the antifreeze and there is no oil in it. I also replaced the PCV. The C/E light is solid and Warm-up Catalyst Below Threshold Bank 1 is the only code. There is no sulfur smell. The idle is mostly consistent.

The reason I am trying to get help from you guys is because I am totally confused by the oil. I'm thinking my next move with be to change the O2 sensor by the front heat shield (and possibly the cracked heat shield for that matter) to fix the light. Although I'm starting to wonder if the c. converter or pre-converter is bad. The car is going to need to pass emissions soon and is ALMOST paid off... But if the rings are bad I might as well try to sell car and save my losses. I'm really lost at this point...

1. The misfiring probably caused the pre-cat to fail (unburnt fuel kills 'em). Replace.
2. The oil could be being burnt - pull and inspect the plugs for oily gunk. Good? Then i would look much more carefully for oil gunk on the engine - it may be leaking only when running (and not overnight like a leaking oil pan). You may have to clean the engine since the VCG probably leaked all over... Check around the cam seals. Check compression before selling 'because it is the piston rings/seals'
3. DO NOT IGNORE the CEL anymore. Take the time to find out. You can go to Autozone and have it read for free next time. No excuses. [end lecture]

-I posted the result for the CE already = "warmup catalyst below threshold bank 1"

-There is no oil anywhere. The engine is clean.

-The "misfire" is very rare, maybe happens once a week.

-I was told that if the rings are going bad then doing a compression test could make them worse.

*I will check the new spark plugs and post results.*

dj binks said:

-There is no oil anywhere. The engine is clean.

Click to expand...

I vaguely remember somebody posting that they were losing oil and it was all piling up in the housing behind the rear engine seal, which was leaking. None of it leaked out of the car until they took things apart, at which point it all drained out of the housing and probably made quite a large and unexpected mess.

Perhaps there is a way to check for oil back there without taking the car apart. Anybody know if this can be done?

Wondering how much it could pile up. The auto has a hole somewhere down there to lock the flywheel with something when changing harmonic balancer & every manual tranny I've ever had had a little hole where the bell housing meets the motor. Definitely a surprise mess..........

dj binks said:

-I posted the result for the CE already = "warmup catalyst below threshold bank 1"

-There is no oil anywhere. The engine is clean.

-The "misfire" is very rare, maybe happens once a week.

-I was told that if the rings are going bad then doing a compression test could make them worse.

*I will check the new spark plugs and post results.*

Click to expand...

I have never heard of a comp test making it worse. It is still kinder and easier on the engine than running the engine....

dj binks said:

-I posted the result for the CE already = "warmup catalyst below threshold bank 1"

-There is no oil anywhere. The engine is clean.

-The "misfire" is very rare, maybe happens once a week.

-I was told that if the rings are going bad then doing a compression test could make them worse.

*I will check the new spark plugs and post results.*

Click to expand...

First off, your front cat is definitely shot. Any sort of bad misfire will kill it in short order. Secondly, you should still do a compression test. If it ends up messing up your rings, then they were being held together anyways with only carbon deposits - personally, I'd rather the engine not crap out on me when I'm on the highway, but instead do it in the garage.

Your best bet is probably to get a used engine if your piston rings are bad, but you should definitely take your car to a professional mechanic before making a major decision like this.