2001 fors ranger 3.0L. Stalls deaceleration and at idle in shop with ac on. No codes. Fp is 64 psi. Changed iac. Maf crank sensor pcm twice fp relay ecm relay as well. Tps moves smooth with volt ohm meter. Has new wires and plugs fuel filter clean like ibsaid fp 64 psi even when it dies. Egr valve is working properly with scan tool iac works with scan tool. I'm at a stump

 

Welcome to the forum.

Automatic transmission or manual?

Could there be water in the gasoline, bad gas?

At cold start PCM should set idle at 1,100rpms, using IAC Valve, does that happen?

As engine warms up idle will start to drop to 650rpms(manual trans), 750rpms(automatic)

PCM uses ECT(engine coolant temp) sensor to detect engine temp, if ECT was reporting engine is at 200degF all the time then no code and engine would stall when cold
PCM just "thinks" you are restarting the engine after sitting for a minute or so, instead of after 4 or 5 hours.


When you turn on the AC PCM should bump up idle by 50-100rpm

If automatic trans then PCM should also bump up the idle by the 50-100rpm when you shift into Gear, if AC was not already on.

 

Thank you. Auto transmission. And no water in fuel took filter off and checked for water and rust and dirt. Temp is right starts like 140-160. And goes up slowly stays around 196 on scanner gauge stays half way or little under. Idle stays high and gradually comes down stays around 850-900 and goes up with ac and same when in gear. I unplug maf and it dont change the way it runs same with camshaft sensor. If this helps

 

o and the mil light does come in when camshaft sensor is unhooked for more than 2 engine start cycles

 

Does it only act up after it is warmed up(closed loop) or will it also stall when cold(open loop)?

Does the column shifter seem tight or loose?
Is the shift indicator spot on, for P R N D 3 2 1

On the transmission is the DTR sensor, it tells computer when trans is "in gear" and it is working if RPMs are bumped up when "in gear", but..............if shifter is loose DTR sensor could be going to Neutral when "in gear" and cause the stalling because there is still a load on the engine.

 

Its does it when its warmed up and the column is right and the shift indicator is in line with scan tool as far as what gear its in.

 

So its something in Closed Loop that is causing loss of fuel, I doubt it is spark related, possible but fuel is just more likely.

Spark is an instant feedback to the PCM so misfire or no fire would tend to set a code fairlly fast.

Fuel on the other hand is not all that well monitored, there is no "fuel pressure" sensor.
Just O2 sensors after warm up
Fuel pump power is monitored, at inertia switch, so if PCM or fuel pump relay was cutting power to pump then that would set a code.

While it would be a pain to set up you could put pressure gauge where driver could see it and then monitor pressure when engine stalls out.
Fuel pump is an electric motor, and they can become intermittent or the wire at the tank can, 12v or Ground wire for pump
I guess that would be the next step in my opinion
Because anything else causing a stall would set a code

 

Ok I replaced tps sensor and I ger the idle to come down from 1100 -1300. I unhooked iac valve idle is down to 650-750 and the idle screw is not touching the throttle. But its not stalling out anymore. ?????? Is there a way to turn idle down any other way than unhooking iac amd turn screw down to 550 and plug iac back in ?????

 

Find the vacuum leak, that will bring idle down to 500, thats with engine warmed up of course

there is no "idle screw" with fuel injection, looks similar but called "anti-diesel screw"
It can be used to make small adjustment to TPS closed voltage, which needs to be .69 to .99, under 1 volt with throttle closed
TPS is mainly used to give the computer a "heads up" that driver wants to accelerate, just using a MAF sensor there would be a delay, hesitation, from when you pressed down on gas pedal and when you got the acceleration.
Had the same problem with carburetors, Jets used vacuum and air flow, so there would be a hesitation when you pressed down on gas pedal, so an accelerator pump was added, squirted extra gasoline into engine when you pressed down on gas pedal, to give instant throttle response and allow Jet's fuel flow to catch up

Throttle body gasket can be a vacuum leak
Older PCV valve can be as well

If you unplug all the hoses from upper intake, one at a time, and seal open port with your finger that will test all of those.


RPM changes in a gasoline engine is done with air, not fuel, adding more fuel to an engine at 800rpms, for example, will get you a flooded engine, not higher RPMs, only adding more air will get higher RPMs.
So to lower RPMs you have to lower access to air, this is why vacuum leaks cause higher idle