Shvitz2k, what year is your car and what's the mileage?

 

[QUOTE]Originally posted by txst
[B]The strange thing is that before and after the cars do the "stumble", they run perfectly.

 

I've always assumed this behavior is just part of the closed-loop engine controls designed to monitor and limit emissions. In the first couple minutes after a cold start, the cat is not up to temperature and the ECU is trying to monitor and adjust everything to minimize emissions while also warming up the engine (conflicting requirements).

I think short-term fuel trim may also be a factor, as I have occasionally noticed a stumble when restarting after a track session -- in that case, the engine's still warm (though the cat may have cooled a bit), but I'd just spent 20-30 minutes in VTEC.

 

Oddly enough, my 91 MR-2 did that when I had it. It did the same exact thing: right after start up, the engine would "stumble" for a fraction of a second, and then it would run just fine the next time I jumped on the gas. I never worried about it much, since it was not all the time.

If it bothers you that much, just have the dealer look at it. If they can't find anything wrong with it, it should be fine.

 

My car was running perfectly the first 43.000 miles, but now it is doing about the same thing you describe.

It is most pronounced when cold, but sometimes when it is hot I can feel it as well.

I have no idea where it came from though.

 

Mine does it once, right after the 3rd light comes on and it is ready for vtec. After that never.

 

my miata has this problem until i cleaned the butterfly valve near the intake. Apparently it was related to carbon buildup near where the intake meets the throttlebody