I have an 05 S2000 with 80k miles on it. Purchase it 5 years ago in 2018 with only 48k, owned by a doctor that barely drove it. In 2020, I installed a supercharger, BC cams, BC springs, ported intake, larger TB, test pipe, skunk2 header, 1000cc injectors, etc.
Engine has run great and has been solid in last 3-4 years with a reasonable amount of spirited driving and pulls....I also have been using AMSOIL 10w30 for all this time. I would say the only thing that I know has been a slight issue is "once in a while" I will see a slight cloud of smoke at wot but only at night when I can see it behind me from street lights. Never really at all during day. Also this past 3 months I have started to notice a considerable amount of oil consumption. About a quart every 1200-1500 miles. No leaks below and no leaks around valve cover. I do have a oil catch can. Lastly. I have been having some oil fouling on plugs 2 and 3 lately. Even cylinder 4 a little...Cylinder 1 spark plug looks great. Looks like carbon as it isn't wet looking but now I am thinking it is oil fouled from guides and/or valve seals.

A week ago, I took the car out one night and did a few WOT pulls as the weather has been cooling down. It pulled very strong and it seemed like everything was fine.
The very next morning I took it up to the store. It was smoking a little after being started (never has before) and continued to smoke a little (bluish tint) if I accelerated past half throttle....As I drove it for about 20 min, the smoking got less and almost went away. Only if I full throttled it, would I see a small cloud. Drove the car home and decided to run some compression and leakdown tests. I had run a compression months before and it was reasonable (210 on all 4). A buddy of mine helped me do a leak down test about a year and a half ago and it was good also although I don't recall the percent.

Anyways, this past few days I have run some tests.

My compression tests (dry) are as follows on warm engine:

Cylinder 1: 210 psi
Cylinder 2: 204 psi
Cylinder 3: 201 psi
Cylinder 4: 208 psi

Leakdown test

Cylinder 1: 7%
Cylinder 2: 12%
Cylinder 3: 14%
Cylinder 4: 7%

So, here is my dilemma. I believe based on my new issues with oil consumption and smoking that there is a good chance it is related to valve guides and/or valve seals. I am not 100% but I believe my rings are probably "ok"....and even if they were a little worn, I really don't want to deal with that nor can I afford to go that route right now anyway. Really hoping most of my issues/gains can be resolved by refreshing seals, guides, and maybe even new valves with a valve job.

I just bought new valve seals regardless and was going to put them in this weekend. Now I am afraid if I do and don't replace the guides (requires removing head), it may be all for nothing eventually once the seals "maybe" wear fast from guides and I would be back in same situation....and if I do decide to replace guides (have to remove head which I would prefer not to), then while I am at it, does it make sense to refresh/replace valves? My compression may also benefit and leak down in cylinders 2 and 3....

So, I have 3 options as i see it.

1.) Replace seals one valve at a time obviously and while valve springs are off, do wiggle test on valve to see if I feel movement. On first valve that I see does have movement, stop there and plan on just removing head and also replacing guides.
2.) Cut to the chase and just remove head and plan on replacing guides and seals. Have valves looked at but don't replace unless they look bad.
3.) #2 plus intentions of replacing valves no matter what (since I already have head off)

I would definitely just do the valve seals if my leak down numbers were all under 10%....Now I think I may have two issues. One is guides and seals, and the other is valves (from compression and leakdown results)

If this was your car, what all would you do?

 

What's your oil usage per 1000 miles?

Thanks!

 

​​​​​​​About 80% of a quart.

 

Just ran another leakdown test on cylinder 3. Still getting 14% leak.

however, I put my ears right next to exhaust pipes and there is no sound at all. Opened up butterfly on Throttle body and it is also silent.
My valve cover and cams are out at moment. I also put a piece of paper up to the dipstick hole and paper didn't move at all.
no bubbles in coolant.

is 14% enough that I should hear it? Anyone else experience same thing? Running air at 100 psi into cylinder.

Forgot to mention, the engine is NOT warm when I run the leakdown test. Car has been sitting for 3 days.

Does anyo0ne think because the leakdown test was done on car that is NOT warmed up that it actually could be better than 14%...say 10% if it was warmed up ?

 

If you warmup the car to operating temperature --- take it for a spin and, say coming down a hill use a lower gear to help slow you down. Then at the bottom of the hill, come to a stop. Now, gun the engine --- does it smoke like crazy?

 

1.First thought is what tuning <ecu>and whats the afr
2.Cams and stronger springs =could wear seats/guides faster ?

 

Good question. I wasn't able to do it and now valve cover is off and cams are out.
What I can tell you is, it smoked quite a bit first thing in morning and continued to slightly smoke on 1/2 acceleration for first 5 min. Then kind of died down after 10 min of driving....If I goosed it a bit, I could see some faint smoke behind me.....slightly smoked at idle. By the time I was done driving it after 20 min, it subsided quite a bit but was still there. I DO believe it may have blown a puff of smoke on deceleration as well. I am just not sure

It definitely felt like there was some oil sitting on top of pistons over night and burned off the first 10 min. By the time I got back to house it was still slightly smoking even if it was very faint...This is why I "believe" it is related to seals or guides.

 

Update: Re-ran the cylinder 3 leakdown. This time I added 2 tablespoons of motor oil in cylinder. The PSI from cylinder stayed about 86-87 psi so still around 14% loss. Maybe improved 1 percent. Now I feel more like it is not the rings.

 

good point! I guess I will hopefully be able to find out by doing wiggle test of one of the valve stems while head is still on car. The last thing I want to do is remove head only to find out the guides are in fact ok.
Plan on removing a spring later tonight and check seal and valve stem movement.
I will report back with my findings/

 

Well, since you have the cams out, might as well try the seals. But, it sounds like you will soon be doing a complete valve and valve guide job.

Good luck!