Idle issues

[mfg3502]

1996 ex v-8 awd xlt This has just started happening.When I do a cold start,the truck idles erratically and wants to stall.This only happens for about 30 seconds then it seems something catches and it returns to normal idle.The truck runs fine for rest of the day.I have great pickup and no issues with hesitation.Things I have done after reading numerous posts.New idle air control,tear off an clean throttle body,new fuel pump,new filter,new wires and plugs,seafoam thru throttle body,cleaned maf and currently running lucas injector cleaner in tank.Also,my mechanic checked for vacuum leaks.None found.Anybody have any other ideas?

 

[KBarbina]

Coolant temperature sensor? - SHOULD throw a trouble code, but I have seen bad ones that didn't. It grounds a circuit to the ECM once the engine is hot so it will go into closed-loop operation, which requires less fuel. If it's bad and the computer is getting the ground while the engine is cold, you may not be getting enough fuel to keep it running. just a thought...... good luck!

 

[mfg3502]

Thanks for the response.I"ll look in to it.Do you know where sensor is located?

 

[ranger7ltr]

The ACT and/or ECT being defective is a good start...

But they send a variable voltage to the PCM to determine engine temperature and air intake temperature and the amount of fuel to input...Location of the ECT sensor will be in the black vertical fitting on the black metal lines on the passenger...It is the gray bodied unit a the top of the vertical fitting...

Also this link goes to explain how both the ACTand the ECT work...

http://www.fordfuelinjection.com/?p=28
http://www.fordfuelinjection.com/?p=29

 

[mfg3502]

Ranger7ltr thanks for excellent reply with pics and explanation.These parts are relatively inexpensive and i"m hoping to do the job over the weekend.Also,my ex is not throwing any codes.Wish it where instead of guessing.

 

[1AJeremyD]

The first OBD2 vehicles have limited computers compared to todays fast codes. You can pretty much do anything you want with the new vehicles from opening and closing purge solenoids to starting the vehicle now just through the reader. Just a matter of time before we are driving our cars like James Bond through his phone via Wifi