noahw526

Hey fella's !

Im stumped, i currently have 3 S2000's and have over 10 years of experience working on them from motor tear downs and rebuilds, engine swaps, AP2 DBW engine modified to fit my Turbo AP1 500HP car etc etc but i am slipping when it comes to this.

I have a 2002 AP1 with the original 140K engine. 100% stock and always has been, it is my wife's car and one day coming home from work i stopped at a gas station and shut the car down. When i cranked it back up it was hard to crank and idled very low for 5 mins and wouldn't rev passed 2.5-3k Ish and it would bog like i has hold my hand over the intake and starving it of air. After 5 mins it would act perfectly normal and i was about my way. This would happen every time i drove the car until full operating temps and then shut it down and try to crank it back up while it was still warm. If i let the car sit until it was cold it would crank up not problem and act fine. One thing to note it is that this only happened when cranking the car once warm and it would never show any symptoms when driving down the road when it had cranked up fine.

This went on for a while and i could avoid the problem if i just drove the car to work and only cranked it when i left when it was cold started. One day on the way home it just died as if the fuel completely shut off, no CEL or anything to indicate the problem it just bogged down and shut off. It would turn over fine but never would fire. SO i took it home and just planned to get to when i could since i had my other S to drive and the only reason i wasnt already driving it was because it was a garage queen.

So i found when i did a compression test and got #1-200psi #2-210psi #3-45 #4-195 so that was a problem, i took off the head and the block looked OK other than Cylinder #3 had a scratch that was deep enough my fingernail caught but the rest of the small scratches i couldnt feel so i thought the block was usable. SEE THE PICTURE ATTACHED

So i took the head to a machine shop and had it looked at it checked out fine other than #3 valve seal needed replacing and everything on the head was cleaned etc and given back to me..

****THIS IS WHERE IT GETS INTERESTING***

Once reinstalled the head i did another compression test and i got #1-150psi #2-170psi #3-185 #4-170.The engine would not crank, i tested and have spark, fuel and the compression listed. I know the compression numbers are low but since the head was just rebuilt i was thinking maybe they just need some use and that they would seal up better after a few engine cycles.

I checked each plug and coil and got spark, my fuel pump primes and i have pressure at the rail and even took out the injectors while still in the rail and had the wife crank it over and each injector sprays fuel as it should. My timing it correct im sure SEE ATTACHED PHOTOS.

BUT IT STILL WONT FIRE !!

Like usual i left it alone for a while once it didnt work perfectly and let it sizzle in my head and just for the heck of it i put some gas in a spray bottle and sprayed it right in the intake at the butterfly valve an cranked it over and it fired just enough to burn the fuel i sprayed in there off. SO i was like what the heck??
I know it has fuel at the rail and i visual saw each injector pumping out fuel so why didnt it start?? So since i could, i took the rail and injectors off my other S2000 that i knew was perfectly fine and swapped them and it still didnt crank but when i put the rail and injectors FROM THE CAR THAT DIDNT RUN on my perfectly fine car it ran fine so i know it wasn't the rail or injectors......

So im stumped.... could my timing be off and i just dont know it? Ive done it so many times but i could still be wrong. Its on TDC for Cylinder #1 when the pictures where taken. so if anyone has any thoughts it would sure be appreciated !

Chuck S

I can't see the timing mark on the intake gear that should be opposite the exhaust gear.

-- Chuck

noahw526

Its there, the gear has oil on it an its hard to see. Check to picture attached

Billman250

Cam timing is correct.

Slowcrash_101

Checked the relays already?

noahw526

I thought so, any other thoughts? im just stumped i can spray gas in the intake and hear it fire but nothing when its just the injectors supplying fuel. I mean i clearly saw and video'd the injectors firing and the only thing that makes a little sense to me would be the timing which is fine...

noahw526

Yes, i have swapped any relay that made any sense to try out with a known good one from my other cars and then put the "possibly bad relays" into my good running cars and they worked fine. I also check all the fuses of course.

BuggyofMildDiscomfort

Cracked a ring or similar and the compression is low - that would fit with it running like a dog till it warmed up and the pistons expanded and the marks on the cylinder?
Extra gas in the intake might have been enough to seal it and get it to fire.

Maybe try the same but with a tiny amount of wd40 or 2 stroke oil down the plug holes, just 1ml or so see if it seals things the same.

windhund116

No possibility of bad gas?

noahw526

The cracked ring theory makes sense to me and would explain the scratch, but the fact that it cranked easy and ran fine on a cold start and ran worse when it was cranked when already warm.. wouldn't that be a contradiction ? Also after the head rebuild the Cylinder with the best compressions numbers is the cylinder with the scratch?

I did run a compression test with oil in each cylinder and i dont remember it having a dramatic change. I might have to do it again since it was a while ago when i did it and dont really remember

Thanks for the input it helps!

I really dont think so, I burn a tank of gas in 2 days driving to work and this all happened when i has halfway through one tank and you would think it would be at the beginning or the end of the tank.