Hey guys, I have a 2004 S2000 with about 170k miles that sees about 30/70 street/track use. I started getting a cylinder 1 misfire code during the last two events of the season. I'm trying to get the car up and running before the start of the next track season (~1 month).

Some background:
The car has some unknown history and probably wasn't treated the greatest before I got it. I'm probably the 10th owner, have had the car for two years, and have been gradually fixing things up as they pop up.
I do most of the mechanical work myself (it's a learning process) but I've also got some great mechanic/s2k friends who help me out.
In the last two events last year (WGI), I was getting multiple cylinder misfire and cylinder 1 misfire codes. After clearing the codes they would typically pop up when idling in the paddock (not while on track).

What's been done so far:
- replaced all the coilpacks with new denso ones
- got replacement spark plugs, but the previous ones were fine (changed maybe ~1 year ago) so left them (see pics below)
- valve adjustment (with guidance of my s2k mechanic friend) -> this cleared the multiple misfire code, not the cylinder 1 misfire
- compression test (it was a cheap tester so the gauge might have just been off; will retry with a different kit later)
- leakdown test (performed by friend because I'm out of town)

Compression/Leakdown Test Results
cylinder 1: 80%, 73%, 73%; 65
cylinder 2: 27%, 23%, 27%; 110
cylinder 3: 20%, 27%, 20%; 120
cylinder 4: 7%, 7%, 7%; 145

Note: compression was done on warm engine, leakdown was done 3x on cold engine (underestimated by ~10%) with 75 psi (OTC tester).
My friend said she couldn't hear where the leakage was on cylinder 1 (checked intake, exhaust, head gasket) but will try again tomorrow with a tissue test.

Diagnosis: S2000 friend suggests an issue with rings (new bottom) and potentially valves (head rebuild). Hopefully tissue test will give some more clarity.

Goals
- track ready ideally by mid-March (unlikely)
- reliable engine for stock power: I like the amount of power it has now (cold air intake with no tune) and would rather learn to drive the car
- I'm currently a grad student (PhD) and not making a whole lot of money, so ideally the cheaper the better but reliability and longevity is key.

So my question is: what are the next steps and what are my options?
1. Is it worth it to get a bore scope and look at the cylinders? Should I do further testing (besides the tissue test)?
2. Buying a used engine or new? Whole engine or just a short block and rebuilding the head?
3. If buying a used engine, how do I vet if it's good or not? Would good compression/leakdown numbers suffice? Should I rebuild it?
4. Should I just K swap it? Is that more reasonable financially short and/or long term? How different would the driving experience be versus keeping the F22C?

Thank you all I've been reading through the forums but am hoping to get some info more specific to my case. Appreciate all the help I can get!

 

https://www.s2ki.com/forums/s2000-ra...urney-1218242/

Good, current thread on K-Swapping with heavy track use in mind.

 

If this is a 04 S2000 in North America, you have a F22, not F20.

The leakdown results are written in inverse, which is unusual. Meaning high number good, low number bad. Usually, its written the other way around.

Idk why there are 3 sets of leakdown numbers per cylinder. What is that? Did she just do the test 3 times?

I would double check the validity of the leakdown numbers.

Your plugs dont indicate bad rings or even a misfire.

However, inverting your cyl 1 leakdown numbers, it would point to like a 80% leakdown. Your friend would hear that even if she were deaf and 5 miles away. Imagine opening a valve on the air compressor to allow 80% of the pressurized air to escape.

Double check your leakdown test. Post here to get more advice.

If its the top end, that's simple. Fix what's wrong and keep rippin.

If the bottom end is the issue...
Don't try to rebuild the bottom end unless you can find a shop which specializes in S2000's enough to tell you the pitfalls of doing so. If you understand fully what you're getting yourself into, then give it a chance.

A K swap isn't a bad idea if you have a busted F series. Budget for $15K, all in, for the initial swap. After that, you'll have the luxury of not worrying much about damaging an expensive engine. It will wear out and break SIGNIFICANTLY faster than a F series (all things being equal), but its cheap and easy to rebuild/replace.

Or...if you're confident you're not going to blow up another F series, buy a used F series and swap it in with minor refresh (gaskets, water pump, hoses maybe timing components). Use your existing F series as a spare. Remember, your current motor lasted 170K. If you can swap in another F series for $5-7K, all in...you should get a lot of miles out of it before you ruin it.

 

Sorry, my bad. Yes, it is a F22C not F20C. And yes, the leakdown values are the opposite. Cylinder 1 has ~80% leakage.

For the 3 sets of results, she did repeat the test three times for each cylinder for validation. I also found it odd that she couldn't hear where the leaking 60 psi was going, but hopefully we get some more info tomorrow and I'll update the thread accordingly.

In terms of the plugs, what would I expect in such a case?

I'm pretty confident that I won't blow another F series (at least not anytime soon). I'm planning to stay NA and not add any power and am also taking much better of the car than the previous owners were. If I look for a used F series, what should I be looking for? Mileage? Compression/leakage values?

Thank you for the help!!

 

I did my K swap last year (F20 -> K24). It will cost you double the cost of an F20 but you get a bit more power and a way more readily available motor. My car is now slowly being converted to mostly track duty so I felt it made sense to go K. Plenty of S2K guys with stock F20/22 doing plenty of track days without issues - so it's really a roll of the dice. I plan to own the car for a long time and I can't imagine the cost of F20/22 in 5+ years.

 

Look for one that's stock and clean looking, with about 210-220PSI compression with single digit variance across cylinders.

Leakdowns should ideally be below 10%, with single digit variances between cylinders.

04-05 is a more sure bet than 06+. 06+ counts on the owner to know to do more frequent valve adjustments. But that should show up in the leakdown, so defer to compression/leakdown results when in doubt.

Miles are somewhat important. A lower mile example is typically going to have less wear and less old, worn parts. But mileage is lower on the list of important stuff.

Look on eBay for a reputable source. TAE and LEEC almost always have motors.

Again...this is *if* you even need a motor.

If your engine's bottom end was leaking all that compression, your plugs would be oil blackened and wet. And you'd be blowing massive smoke.

 

Not a bad plan and can't argue with this logic.

The more track use you have planned, the higher the likelihood of something bad happening to your engine. If you don't do anything crazy (money shifting or running low on oil, for example), the F series will last and last and last.

The K series just puts your at peace of mind. If something goes wrong, its not a big deal.

 

So it turns out that the leakage was coming through the throttle body.

Talked to a few of my S2000 friends and they're all saying that the most affordable option would be to just rebuild the head. New upper engine gasket set, engine oil, coolant, oil filter. See how many valves and valve guides are needed upon inspection and replace accordingly. Get the head decked, hot tank cleaning, parts replaced, then valve job (adjustment?) and pressure check.

Does this sound about right? Should I go ahead and replace all the valves/valve guides since I already have the head open or should I only fix it if it's broken?

Should I still consider replacing the motor since the numbers aren't looking great and used prices are fairly low right now (~$4500 for a good one by these standards)?

Thank you so much for answering all my questions!!!

 

problems with the head are relatively easy to fix

the head will be off and apart, so yes, new seals makes sense. Avoid new guides unless you need them, as they need to be pressed in/out.

Buy everything you need from a Honda dealer.

Don't mill the head. You can skim it. But don't mill it down.

Good luck!

 

+1 on not milling. It messes up timing chain geometry. Not typical on most engines, so machine shop will probably recommend or even insist. You need to be more insistent.