Yes ofcourse, but that wouldn't explain the stalling.

ECU should learn not to let the engine stall, but it doesn't or it can't.

 

The CEL is gone?

 

CEL doesn't appear with testpipe

I've installed the testpipe again to be sure my cat wouldn't melt

 

I was wrong, it does appear with testpipe! Only after idling for a while.

Spent the day with a guy who knows his Honda's. Unfortunatly he also can't pinpoint the cause of this.

Temperatures are higher the last few weeks and today it just wouldn't stall after we adjusted the idle screw back to factory. It wanted to die a couple of times, but didn't. Could be the temperature, or the fuel additive I put in last week.
Idle vibration, low rev jerkiness and other problems were still an issue though.
Valve clearance, timing, vacuum, ... everything checked out fine.

The only remark he had was that the crankshaft was hard to turn in comparison to an other S2000 he had a while back. It went up to a point where it took a lot effort to turn and would then "shoot through it". He suspected the dual valvesprings to be the culprit of that. Might possibly also cause the vibrations and maybe the rest of the problems.

An other issue he noticed while using a stethoscoop was one injector which was a bit louder then the others. We switched it over and it suddenly became a lot quieter. The injector which was now in the spot where the noisy one was, was also very quiet now.
Allthough the injectors came back fine from a testing rig, he still suspects they might have something to do with this.

One other thing I noticed was white smoke from the exhaust whilst revving the engine. The engine had been shut off for a couple of minutes and after startup the white smoke was definetly there, even after some revving it kept on blowing clouds of white smoke (like it does in cold weather). The engine was still at operating temperature though.
Coolant checks out fine, no drops in level.
Might be because of the testpipe?


To his opinion it could still be the injectors, or the ECU or even possibly those dual valve springs....

 

Compression test for fun...Just to rule out mechanical problems...Maybe even a leak-down test....

 

Compression has already been tested 3 times

Every time very consistent between all four cylinders.

 

I did the valve adjustment myself, and the "shoot through it" part seems familiar. Don't know if that's normal tho, but I'll ask my mechanic.

I seem to have AP1 retainers, but I don't know about valve springs.

Also, I'm inclined towards injectors, I will switch them with a friend and we'll see what happens.


Edit: the cranking might be related to my transmission not fully disengaging. Maybe it's the same for you.

 

Well, the dealer and another mechanic never mentioned this "heavy crankshaft" issue. Might be related, or not.

Vibration at idle, stalling, jerkiness at low rpm and slight hesitations... It all seems to point at MAP sensor issues or vacuum leaks. But they're all fine...

I'm also still suspecting a small leak at the intake manifold gasket, but I would suspect this would lead to a higher idle?
At cold start, the revs do shoot up above 2000rpm for a brief second. Can't remember this being normal?

 

Were the spark plugs out when your tech noticed the difference turning the crank?
Do you know if your engine has a higher compression, decked head?

 

Yes it is normal.
Horrifying.. but normal.