Low RPM / Stuttering - Inconsistent

[jwunsch]

all normal hot is 750 to 850 RPm spec.
cold varies by out door temp and for sure how cold the coolant is, at 150F the cold temps end and hot 800 arrives.
the lower RPM is the EGR main sticking open
as you come to a stop or just cut throttle to zero, (right foot) the EGR is command close, if it dont close rpm can go to 400RPM and engine misfires and shakes hard.
a very common thing, this,  EGR might be cleaned (main) to cure this, 50% change of success. if EGR is super old , chances less.

Im pretty sure this is it,  and not something far worse.  injectors leaking or crank pulley front falling off. is it loves to do latter.
good luck to  you !!!!

This problem isn't very consistent, I sense that when I've been driving the car for a while (at least 15-20 minutes and its very warmed up) the idling problem goes away.

^ I had the same, my problem's inconsistency was very much linked to outside temp and what speeds I was driving. Fine at 10C, not fine +5C - 0C or below 0C (Fine at 50F, not fine 41F - 32F or below).


I suggest getting IR gun to check the STAT housing to verify temps after driving say at least half a hour. I had similar issues with -91 Vitara G16a (Sidekick in US?).  My posts (1991 Vitara G16A frigid) but probably not worth reading all that b$.

My old STAT was open at all temps, fan clutch was semi sticking etc.

I replaced STAT, fan clutch and they helped a lot, but here at winter the car still over cools, so I blocked RAD with cardboard as I some times got CEL 13 due to to low temp and O2 sensor test failing.

After adding block for RAD those stuttering issues ended. (RPM going so low even RPM meter shows 0, but engine still manages to bounce back to idle). Anyways It's easiest to check the water temps before you go deeper into EGR and other stuff you need to dismantle.

As far as I can guess, if the temp too low ECU has problems guessing if it should use "choke" or not. And when you constantly linger on the borderline it causes problems (and high fuel consumption).

ps. Additional benefit, I can get the cabin hot now