So I recently bought a 1991 E350 superwagon, 5.8L 351 V8. Van starts right up but if you do not wait until it reaches operating temp it will stall out when put in any gear. After it warms up (5 min) it shifts into gear without stalling. Curious about any ideas I can take to help it run a bit smoother when cold. New parts just installed in the van are as follows:
Idle air control valve, TPS, engine coolant temp sensor, idle tensioner/belt, spark plug and wires, distributor cap/rotor, ignition coil, MAP sensor, fuel pressure regulator and fuel filter. Many vacuum lines were replace already that I can see..

 

In this vehicle, the ECA is supposed to increase engine RPM to accommodate the increased load when put into gear. There are a few inputs that the ECA monitors and either the message (signal) is not being sent to the ECA (vehicle computer) or the ECA is not responding when shifted into gear.
Does the engine run at higher RPM when cold and first started?


If someone replaced a bunch of vacuum lines and mixed them up that might be part of the problem.
Ex. EGR working when cold , should not be.

 

Even though you replaced the IAC motor (which probably wasn't bad) did you also clean the throttle body? The bore on the throttle body which the IAC resides will get carboned up.That will affect the operation of the IAC and the amount of air which is metered into the intake..

Many times there are two ECT sensor/ sender. One for the computer and a sender for the dash gauge. Did you replace the one which feeds the computer?

 

Thanks for the replies fellas.. so to answer the first question yes it does idle higher at start up.. The previous owner did an EGR delete on it so I don't really know if that would have an effect also.. the throttle body was cleaned when I took it off and the coolant sensor that was replaced was for the computer not the gauge. I mean granted the van misfired and barely idled when I bought it so there is definitely a big difference now , just that cold start idle issue when put in gear.. Thanks...

 

If,,,,,the engine does idle at a higher speed when cold and first started ,it would tell us the computer is responding to the temp and raising idle speed accordingly.

What we need to follow up on is, when the trans shifts out of park or neutral the computer should raise the idle speed to accommodate the increased load.
One way that is accomplished is by way of the switch on the trans that notifies the trans controls to react, which seem to be working OK.
I would want to check the plug at the trans for any corrosion first. to see if there is any possibility of the signal from the trans sw not getting to the computer.
Let us know what you find,thanks.