Engine Runs After Turned Off

[adamp]

Ok, I have a 1992 Ford Explorer V6 4.0L and when you turn the truck off, it will sputter and deisel a bit and finally die, or sometimes I have to turn the key back to on and gas it to make it die.
I am also experiencing the pinging noises when the truck is under a load. I have read mosts of the posts concerning the pinging and will try those suggestions, but I haven't found any info about the motor still running. Please let me know if you got any info.

Thanks - Adam

 

[spiper]

Check your EFI. It may only need to be cleaned to stop the over run.

 

[adamp]

How would you go about cleaning the EFI. Is there a sensor that you can clean/replece or do you just mean clean the injectors themselves. If so, how do you normally try that. I have never trusted anything in a bottle what you can pour in a gas tank that will clean the fuel system, but who knows. Let me know.
Thank again - Adam

 

[FORDisKING]

There are possible deposits in the tips of the injectors block fuel. Either that or this is not a good sign. I have never heard a EFI engine diesel. Try STP Complete Fuel System (in Silver plastic container) put it in after an oil change. They just might need replacing though. How many miles are in this engine?

Jason

 

[adamp]

The motor has about 102k miles on it. I have tried the STP fuel system cleaner that you add into the gas. I figured that it might need new injectors. One concern that I have is that it could be the timing since the motor is still turning over. I keep wondering if any of this could be related to the pinging you get when the car is under a load. Let me know what you think. Thanks again - Adam

 

[james t]

pretty sure its the timing. from what you say, it also detonates? any time an engine "diesels" after you turn the key off its usually the timing. try runnin' a tank of high-octane fuel with some octane booster. if it gets better, your proly runnin too much advance...

 

[Lemondrop]

Fix the pinging first . Id clean your mass airflow sensor . The dieseling is from deposits on your piston and or valves . Running a higher octane fuel will cause even thicker deposits . Run a lower octane fuel and clean the MAS . The ping you are getting is from the cylinders leaning out . The spark plug ignites the air/fuel mixture . When the MAS is dirty the engine thinks you are just running a light load or idling . It will not send enough fuel to the injector(signal) for the engine to run correctly . You then get the "ping" from the mixture igniting too fast . It actually burns everything in the cylinder before the piston reaches top dead center (where the burn is supposed to take place) . This makes you pistons extremely pissed-off . They crowns get HOT ! Crown is the top or head of the piston . Ive seen many engines that pinged so long that it melted the piston crown and blasted it into the oil pan . Once your pistons are this hot , you shut off the engine and now the piston and deposits stuck to it act like a sparkplug . Also , with it being a EFI engine , one or more of your injectors must be leaking . Either they are leaking on the lower orings or the tips are letting fuel bleed through them after the engine is shut off . That is the only way it would continue to run .

Clean the MAS , change your fuel filter , replace the spark plugs . Then consider having the injectors professionally cleaned or replace them . You might be able to remove the injectors and replace the orings on them and have them stop but I imagine if the orings were leaking the engine would smoke and run like crap .
If you want to remove deposits from the eninge , remove the inlet pipe (at throttle body) and get a spray bottle . Fire the engine up and open the throttle while spraying a little shot of water down the throttle body . Might even work with carb cleaner but it can backfire and cause you to get burned
Don't blast alot of water , just a little mist and keep reving the engine up while spraying . This will remove deposits from the valves and cylinders but you don't really need to do it . A nice long freeway drive at 70MPH blows deposits out very well also .

 

[james t]

yea, try cleaning the mass air sensor. i suggested trying the high octane for ONE tank only to see if your timing is running too much advance. there could be problems with the computer, ignition in this area. if your timing is advanced too much, the high octane fuel will help curb both the detonation and the "dieseling." if this works, then you know what is wrong. the deposits could be bad enough to cause the detonation, also. but, ANYTIME i have seen a gasoline engine detonate AND "diesel" @ shutoff, it was the timing.

 

[01EB5.0]

i would say get different spark plugs....sounds as though the ones you have are of the wrong heat range. either that or your timing is off

 

[adamp]

Ok, I pulled the injectors and the shop is saying that none of them are bad (leaking). They are going to clean them. What else could it be? The plugs look fine, I've cleaned the MAS, can't find any vacumn leaks, fuel pressure regulator looks good. Any ideas? Thanks - Adam

 

[adamp]

Ok, now I have replaced the fuel injectors, the fuel pressure regulator and the truck is still dieseling after you turn it off. I have tried cleaning all tha carbon out of the cylinders, nothing. We checked for vac. leaks, nothing.

Anyone know what it could be. It runs very good and doesn't seem to be detonating so I don't suspect timing, but what do I know. Maybe EGR, maybe an ignition short, maybe ICM. Please help, I am about to drive it off a cliff.

Thanks - Adam

 

[01EB5.0]

Adam,
It soulds like a timing issue to me. I know you said you don;t think thats what it is, but it's either timing or spark plugs that are too hot.

 

[TPLYNCH]

Replace the FPR if you haven't already. Just because it looks good doesn't mean it's not taking a crap on you. They are notorious for going bad and dumping excess fuel....