I had my valves adjusted recently by a reputable local shop, begins the story. After initial startup, the tech thought the valves sounded a bit tight so he went back and redid them. I noticed a lug/chugging in the lower RPMs so I took it back and had them check it again, stone cold. Tech who adjusted the valves said they were in spec.

Here's where things start sucking:
The hesitation in lower RPMs hasn't gone away and it's been about 1100 miles. Kind of a little lag and then the engine gets up an goes, at least for the first few hundred miles or so after the valve adjustment. It's actually getting worse, the car feels like it's way down on power. On a recent road trip to Atlanta, I was shifting from 1st to 2nd and when I pressed on the throttle in 2nd after engaging the gear, the car starting breaking up. Almost like it wasn't getting enough fuel. Scared the hell out of me.

So far, it's not gone after resetting the ECU, buying a new MAP sensor, running fuel injector cleaner, etc. I'd really like to know what's wrong with my car.

 

Did they do a compression check before the adjustment?

 

how long was the car in their possession?

 

You know what...I've noticed that too. I got mine done a long time ago and ever since then its been way under power. I never put those two together.

 

No, a compression check was not done. The car was there for half a day the first time, then a full day when I took it back.

Little background on the car, it's an '02 with now 132xxx miles.

 

How out of spec were the valves when they were adjusted the first time? Do you trust these guys to do the job properly??? I've never heard of anyone doing a VA and then saying the valves sound tight, and then doing it again. I'm thinking if the valves were way out of range the first time, perhaps the ECU has adjusted to run with that.

 

Should have done a compression check b4 the adjustment. I'd do one now to see where your motor is at. It'll be a good starting point.
Check the plugs while you at it.

 

I did this - called myself a right muppet after - mostly because I'm a very experienced mechanic who knows better than to rush. Bottom line I read the spec in metric then picked up an imperial feeler guage set. 16 valves all perfectly adjusted to the wrong setting. I guess the man that never made a mistake never made anything!

Symptoms were rough idle, low power, and MIL light (though I've been chasing as yet unresolved air pump issues that make this the light a bit random to this day).

I'd look to the basics if I were you - it was right last week, now it's not, backtrack through what's changed since and double check. My advice is do not drive it if you think the valves are tight - you will only burn them which is a whole other world of expense.

 

I'll do that, guys.

Thing is, we checked the next day, like very next day and they were within spec. I trust the shop to do it right, the guy who did it used to work for Full-Race.

Compression check tomorrow, and I'll report back.

 

Did your mechanic measured your valve clearence from the cam lub and rocker arms or between the valve screws and the end of the valve? A lot of S2000 owners make the mistake of meassuring their valve clearence from the cam lub and rocker arms thinking that the valve adjustment procedures are the same as the b-series.

Also, adjusting the valves on s2000 from the cam lub and rocker arms will cause your clearnce to be, I believe, 0.005 looser than OEM spec. I know for sure that having loose valves will make you loose some power low end, but your high end power would feel the same.

Do you hear tiny ticks coming from the engine?