I have been fighting an off idle stumble on a D16 (ZC SOHC Vtec - same as a Z-6) for some time now.

Logically, one would assume that there was an air/fuel problem at low RPM, so I set out to figure what the problem was.


1.) I checked for a vacuum leak by spraying starter fluid around the hoses and gaskets that connect to the intake manifold. (CAUTION) Starter fluid is highly flammable, use at your own risk!

2.) With a multimeter, I checked all the sensors, and all tested out fine.

3.) I was worried that I had bad basemaps for the ECU, but before I started jigging with those, I decided to remove the throttle body and check for any internal leaks.

What I found was that the throttle body was caked with carbon. Literally, the butterfly would not close all the way, thus any adjustment on the idle screw did nothing to change the idle of the engine. I ended up just changing the throttle body, but I am sure a good cleeaning would have fixed the problem.

My off idle stumble is now gone.

I decided to share this in case others might be out of ideas for the same situation.

 

will look into this

 

Thanks for posting this, having same problem. Hopefully this will work.