96 Explorer Running Rough when hot

[phipps]

I have a 96 Ford Explorer with the 4.0L V6.

The vehicle starts and idles fine when it is cold, but if you shut it off, run into a store for a few minutes and then come back out it is harder to start and idles really rough. Occassionally it will die. If it is only shut off for 5-10 minutes it starts and idles fine. After you get going it goes away and runs fine.

I'm guessing a sensor is acting up, but not sure which one I should be suspecting. Any ideas/thoughts would be appreciated.

It does have a MIL on right now, however it was doing this long before the MIL came on.

[shorod]

Sounds like common symptoms for a failing electric fuel pump.

You really should get the codes read though. Many of the chain auto parts stores will perform this service at no charge. Maybe the code will indicate another issue that may remedy the fault. It is possible for problems to compound take some time to get so far out of spec that they trigger a diagnostic code.

-Rod

[phipps]

Originally Posted by shorod

Sounds like common symptoms for a failing electric fuel pump.

You really should get the codes read though. Many of the chain auto parts stores will perform this service at no charge. Maybe the code will indicate another issue that may remedy the fault. It is possible for problems to compound take some time to get so far out of spec that they trigger a diagnostic code.

-Rod

Replaced that a year or so ago. It did it before we replaced it and still did it after replacing. I really think it is a sensor getting "heat soaked."

I will get it in to AutoZone to get the codes read.

[chupakabras]

the engine have sensors and actuators,. sensors send info to the computer, then the computer uses the actuators to control the engine,.
sensors,. MAF SENSOR, CRANK POSITION S,. THROTTLE POSITION S,. COOLANT TEMPERATURE S, KNOCK SENSOR, CAMSHAFT POSITION S, OXYGEN S, AND OTHERS, these read and send info to the computer,

the actuators are electro mechanical components, like, FUEL INJECTORS, IDDLE CONTROL VALVE, RELAYS, and others

the most common problem when the engine iddles rough or wont iddle and shuts down and hard to start, is the IDDLE CONTROL VALVE, that controls the amount of air needed to start the engine and to control iddle speed, also and very important, the engine coolant temperature sensor, even if you already replaced the fuel pump, you have to perform a fuel pressure test, dont forget to check for vacum leaks, if you have vaccum leaks it will iddle rough or wont iddle at all,. good luck.

[phipps]

Is the coolant temperature sensor for the computer seperate from the one for the temperature gauge?

[shorod]

Originally Posted by phipps

Is the coolant temperature sensor for the computer seperate from the one for the temperature gauge?

Yes. You might also remove and clean the EGR valve. If there is a lot of carbon in that, it could be preventing the EGR from closing completely at idle and causing a vacuum leak. The consistency of the carbon can change due to temperature.

What about a general tune up, when's the last time the vehicle's had one of those (fuel filter, plugs, plug wires, air filter, etc.)?

-Rod

[wrightz28]

Originally Posted by shorod

What about a general tune up, when's the last time the vehicle's had one of those (fuel filter, plugs, plug wires, air filter, etc.)?

-Rod

Also, once again, I'm more of a GM guy and this type of scinerio ended up being a ignition control module on it's way to autoparts heaven.

[phipps]

Thanks for all the suggestions! When it warms up I will start looking things over.

It is due for a tune up.