S200 OBD2 P28 stalling problem

[roach]

I am having a stalling problem on decel and not sure on what to do to fix this problem.

It stalls almost everytime (when slowing down or coming to a stop) except if I blip the throttle before I go to neutral(manual transmission). Although, it does not stall when I blip, the rpms do fall below the target/idle RPM (set at 1000rpm) and than bounce back up to the target/idle RPM.

Car drives well; idles fine and accelerates fine; only the stalling problem when slowing down or coming to a stop without first blipping the throttle. (Really dangerous when coming off the freeway offramp and stalling with cars right behind me) BTW, after stalling, car starts up right away and idles/drives fine.

I am not sure if this is A/F ratio related, Timing related, Vacuum related.

[Hondata]

First check that the idle valve is working within it's range by unplugging it and checking the hot idle drops to ~650 rpm. It sounds strange but if there are enough vacuum leaks to allow the engine to idle at 1000 epm (or whatever idle speed is) then the idle valve is right on it's minimum opening and won't respond well to a request from the ECU to increase idle (in decel). If the idle is too high with the idle valve unplugged then reduce the amount of bypass air by screwing in the adjustment screw.

Second in RomEditor bump the idle adjustment a couple of notches to the right - that should do the trick. Too far to the right and the idle will tend to 'float', and take some time to fall back to the idle speed. Too far to the left, and the engine will stall in decel, which sounds like the problem you have.

[Spunkster]

Also unplug the evap purge valve which is either on the firewall or on the manifold as this sometimes on OBD2 cars will cause stalling.