jedow

Yeah I understand, 225,000+ Miles on it and now along winded book of questions..But I'm confident its not just the mileage. Barely any problems,especially compared to all my past cars. I have been having Multiple Misfires for a week now,with intermittent power.Been down the coil pack road before. I checked them all,and all seem in decent viable shape.Same with plugs,changed them all out.Had a little oil on 2 & 4.But that's a given since I've been pushing back the valve cover gasket.Which may be the issue?Except now I have a broken VC Bolt and just snapped a Coil Pack Bolt. 3 Days until the VC Comes in,since I cant figure out the size, I had to order through Stealership. I map whacked it aqnd nothing new. After the plugs it runs a little better,but the problem still exist. It keeps putting around like a lawn mower.Has very little power and kicks in at high revs and throughout the rpms with no consistency.But even that falls off depending on how fast I accelerate and push the gas.If I come off the gas a little,its a bat outa hell,until a few seconds latter,if feels like someone is hitting the brakes. then it Bucks,yes or like a kangaroo.And yes I read all those forums and nothing fixed.Oh and the CAT is on its way out.Had a CEL a few months back after a shot coil pack and the CAT OBD CODE never came back.So I start the car,seems nice for 20 SECONDS,no CEL.Then after the rpms start to drop, the Damn CEL comes on and it starts shaking violently. I try to drive, but it feels like the emergency brake is on. Then if I back off the gas a little it runs great.I cant figure it out.Has anyone else have this problem or someone with a solution?

I did SeaFoam it in the gas tank during the week to hopefully figure this out and it seems like it got worse.Here are a few other questions in addition to the above. Every time I unplug the battery and reset the cpu and the codes erase, if there is still a problem with the erased code will it come back?Since Im only getting misfires codes.Like if I had a Sensor code,erased it, and now just misfire codes, or will a bad sensor code keep coming back until replaced? I figured coming back,but I'm reaching for straws at this point.And the whole coil pack issue that occurred a second ago,sorry at 225,000+ these bolts weld themselves to everything. So, the coil pack bolt hole is somehow stripped a little and now loose,I can Helicoil it, but it seems the bolt hole is in a sleeve attached to the Valve cover. Is this true? Can I work the sleeve out and replace it .Or do I need to Helicoil/ REthread? And lastly, if its the fuel injectors and the seafoam didn't work and I have a bad injector, how can I check it myself?Is it difficult to check the injectors,is there a forum/thread somewhere?

BTW Since 2003 and over 225,000+ miles and a few minor issues, I've been using S2ki as my bible and its always helped,especially for an inexperienced mechanic like myself, who cant trust mechanics that don't know this car.Or a rip off dealer.I wanted to THANK EVERYONE FOR ALL THE HELPFUL INFORMATION AND IDEAS.Its made my S2000 experience significantly Better and More Enjoyable. THANK YOU!

Supra-holic

Read Misfire thread if not already.

Things to check.

Mechanical condition:
Compression Test, easy test
Leak down, little more in depth on set up but more accurate on condition
Also, check throttle plate, air filter and pcv are clean. My throttle plate was pretty dirty at way less miles as you, 166K, this was causing the car to run like crap at idle
When was the last valve adjustment?

Spark:
Coils, you said you verified they are good, how?
Plug condition

Fuel:
Injectors, not sure on how to test these other than to pull the rail and pressurize to see any leakers

With this amount of miles I would be cutting oil filters open at oil changes to inspect and sending the oil out for used oil analysis.

Good Luck.

DFWs2k

Check injectors if youve looked at coil packs and plugs already

zeroptzero

like the guys metioned above ^ for sure, the injectors could create isssues. Plus I'd change the MAP sensor at that mileage. Oil leakage will cause misfires. If your cat is plugged due to broken bricks inside of it, that will create problems. I am pretty sure you can re-thread the valvecover, I did it for my TDC sensors when those threads stripped on me. The oem bolt size is 6mm, I just opened them up to 7mm x 1 using the proper sized drill bit and tap, and then put in a 7mm bolt, it's a simple job.

cyrusakakumar

I had that same problem as well. Did you do a leak down test? or atleast a compression test. I had a burnt exhaust valve in cyl 4 in my AP1. Ended up just swapping the head and doing some head work. Compression tests are not that hard to do and it will narrow down your solutions. If you do not know how to do it, any shop should be able to do it for an inexpensive price.