Hello!
I have a '93 yota motorhome with the 3.0.. It was idling rough and would about choke you out from being to rich/rough. Would set a code of the air temp sensor out in MAF sensor. Warmer the motor/ambient temp and the worse it was. Finally got a rebuilt one from NAPA. Now, runs fine as it warms and once warm it idles fine and then dies. No codes. No warning. In other words no stumble for a few seconds before it dies. It skips one beat and dies. Idles smooth up until then. Hoping someone has a clue for me.

Thanx in advance.

 

Sounds like it is dying as it transitions to closed loop mode as it is warming up? When it does this it is no longer using a canned algorithm for fueling and ignition. The TPS/Throttle Plate and AFM need to communicate via the air pipe that is between them so is it intact or does it have a split in it that you can't see easily. Is the fuel pressure regulator getting vacuum signal from the plenum there is a steel pipe section that was plugged up on my 4Runner and this was causing over fueling as the fuel rails pressure would not regulate as the regulator never saw any manifold vacuum when the throttle plate was closed. Almost ruined a new CAT after the rebuild in trying to figure this out. AFM is new to the ECM so how old is the temperature sensor on the rear water manifold that the ECM uses to tell its self how warmed up the engine is? That also might be worthy of checking out to see if it is delivering signal to the ECM. The TPS and AFM and the temperature sensor are key for the ECM to operates as are the position sensing coils in the distributor to tell the ECM were the crank shaft is positioned. All of these work in concert when in closed loop after engine is warmed up. The O2 and the knock sensor are also in on this game as well!

 

"The TPS/Throttle Plate and AFM need to communicate via the air pipe that is between them ..."

​​​so much​​​ NO.. I'm gong to assume you were trying to explain that the air flow meter unit also controls the power to the fuel pump, IE the vafm turns the fuel pump on or off based on receiving a minimum air flow or not.. Commonly referred to as "classic COR troubles", you want to do the fuel pump diagnostic by jumpering the fuel pump diagnostic connector to power (fp to b+)

 

You have left us with nothing but questions!

What code?

What did you replace from Napa?

Can you keep it running with the throttle? As the cold idle starts to change from high idle to low idle give it some throttle pedal!

​​​​​​If that keeps it running it's starving for air, mark you idle screw relative to the throttle body now screw it all the way in and make a note of how many rotations this is. Now pull it all the way out check and maybe change its oring. Run it back in all the way till it stops and back it out one full turn past what you noted. Warm it up and see where the idle settles.

 

Going to look up "classic COR problems". It was the VAFM I replaced from Napa. Thanx for responding you guys.