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96 Explorer rough idle

Whedbeec

New Member
Joined
July 12, 2021
Messages
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City, State
Ormond beach Fl
Year, Model & Trim Level
1996 Explorer 5.0L V8
Help! My sister has a ‘96 Explorer that originally wouldn’t start, when we did get it to start the idle was very rough. Changed the air filter, cleaned the throttle body, replaced the fuel filter. The idle got better, but now when accelerating if you’re giving the truck gas and immediately let off the gas pedal, the RPM’s go down and it struggles to stay idling. It will stall if you slam on the gas and then pull off of the gas quickly. PLEASE HELP
 



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When asking for help, it's always advantageous to specify type of engine, whether any engine codes are present, prior maintenance history (aside from parts you just replaced), mileage, etc. Could be a vacuum leak, faulty IAC sensor, plugs/wires, MAF sensor, etc. But, rather than continuing to throw parts at it, first check for any codes.
 






If no codes show up I would next go to fuel pressure test.....sounds like possible fuel pump on it's way out.
 












My vote
Iac and or fuel pump
 






Help! My sister has a ‘96 Explorer that originally wouldn’t start, when we did get it to start the idle was very rough. Changed the air filter, cleaned the throttle body, replaced the fuel filter. The idle got better, but now when accelerating if you’re giving the truck gas and immediately let off the gas pedal, the RPM’s go down and it struggles to stay idling. It will stall if you slam on the gas and then pull off of the gas quickly. PLEASE HELP
Plugs and wires should be next.
 












idle air control valve
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Help! My sister has a ‘96 Explorer that originally wouldn’t start, when we did get it to start the idle was very rough. Changed the air filter, cleaned the throttle body, replaced the fuel filter. The idle got better, but now when accelerating if you’re giving the truck gas and immediately let off the gas pedal, the RPM’s go down and it struggles to stay idling. It will stall if you slam on the gas and then pull off of the gas quickly. PLEASE HELP
Was having the same problem with my 96 Explorer XLT, replaced the idle control sensor and it cleared right up for me, may be something different with hers but the part isn't expensive so give it a try! BTW there wasn't any engine codes while it was doing this so I just guessed at it.
 






Help! My sister has a ‘96 Explorer that originally wouldn’t start, when we did get it to start the idle was very rough. Changed the air filter, cleaned the throttle body, replaced the fuel filter. The idle got better, but now when accelerating if you’re giving the truck gas and immediately let off the gas pedal, the RPM’s go down and it struggles to stay idling. It will stall if you slam on the gas and then pull off of the gas quickly. PLEASE HELP
Hi There, FATK here. I just now finished up my Dad's 96 Explorer with the 5.0 V8 that had the same issues as you have described. BTW it used to Lope at idle too. Here is what I did and here is what finally fixed all the problems at once. I cleaned the MAP sensor, replaced the MAP sensor previously. I cleaned the Idle air control valve. I replaced the throttle position sensor. I previously found an intake vacuum leak and changed the intake manifold gaskets. When you first start the car when it is cold it starts in what is called OPEN-LOOP. That means the engine is running on preset values that are not changing base on all the sensors on your car. When the car reaches operating temperature the controls system then changes over to CLOSED-LOOP Control. That means that the PCM/ECM (the computer) is taking all the information from all the sensors and making decisions on what to change in the engine to make it run properly based on a bunch of stuff in an Algorithm (fancy equation). Any one of your sensors could potentially cause problems with how your engine runs. Now with that being said, most of the time you get a check engine light that will alert you to have someone check what engine code(s) are making the check engine light come on but, sometimes no code is present. Imagine that with all that fancy technology. Well that is exactly what happened to my Dad's car. I had a sneaking feeling that it was a fuel pressure related problem because of the poor exceleration and coughing. I did have a fuel pressure gauge kit to tie into the fuel line to check that out so I ordered on off of Amazon. Well it did come in in time so I proceeded to change the fuel filter. BTW, you will need to get this cheap little tool at the parts store to release the quick disconnect fuel line fittings. Just get it when you buy the fuel filter to save you a trip. Take the Negative Battery cable off of the battery and wrap a rag around it so it doesn't touch the Negative Battery Terminal. Well I took out the old fuel filter (Gas will squirt out probably a little so wear some safety glasses and have a catch pan and rags. It is located on the inside of the driver side frame rail just in from the back edge of the drivers door under the car. Mine rattled like it had a walnut inside of it so I knew it was done. That made me think that probably the fuel pump was also suspect. I removed the gas tank. There are some good YouTube videos on that and it is not a lot of fun. I would rather get bit by a Python down here in Florida rather then have to take out the gas tank again. Well I love my Dad so I pulled the tank out. When I looked inside of the tank after taking out the fuel pump assembly I saw a bunch of junk in the bottom of the tank with what little gas was still in the tank. I syphoned out most of the gas before I dropped the tank out so it would not be so heavy. I am glad I did. The junk in the bottom of the tank turned out to be the suction filter for the fuel pump. It has fallen completely apart and was getting sucked up into the fuel pump and system. I was lucky that it did not mess up the injectors. Anyway I bought a fuel pump for about $30 bucs and changed out the old one in the assembly. Very easy to do once you get the tank out. If you do the pump and filter yourself you will save a lot of cash. Now once you are all back together you have to do this before you just drive away. Get a jumper wire with alligator clamps on both ends or some like that and connect it between the Positive Battery Cable that is still on the battery and the Negative Battery Cable that is wrapped up in the rag. Let it stay connected for about 1-2 minutes. This is kind of like resetting the memory of the computer so it will have to learn everything over again. Take the jumper wire lose and reconnect the Negative Battery cable. Make sure you have at least 5 gallons of gas in your tank. Remember, you fuel line, filter and most tubing is empty so it will have to fill up before your car starts and this is how you do it. Turn you key to the on position. If you listen closely you will hear the fuel pump cycle on for about 5 seconds then turn off. I will make a certain sound. Now turn the key off then back on again. The pump will sound the same. Keep cycling the key until you hear the pump sound change pitch. Remember that sound and keep cycling the switch until the sound changes again. It will sound like the pump is having a harder time pumping. That sound means is has filled everything and is building pressure. Now start the car. It will start right up and idle. Don't rev the engine, just let it idle for about 15 minutes which will bring it up to the proper operating temperature. During this time the car's computer is in a "Learning" mode because you wiped out it memory of certain idle settings. Now you will need to drive your car for about 15 minutes to let it learn how you drive and when to shift gears so just drive normally not like like you are trying get beat that old lady next to you to the next traffic light. Sometimes they are pretty quick and you don't want that when your computer is learning. After that you are all done. It work Great for me. You can probably skip changing out all the parts in the beginning but, I would recommend cleaning them. There are a lot of YouTube videos for that stuff.

I do believe that the faulty fuel pump and the bad filter was the main factor in the problem. I am not sure but, I believe the computer is telling the fuel pump to pump at a certain speed for certain throttle positions and conditions. If the fuel pump was not pumping effectively and the computer just assumed that it was working just fine then I could understand why it was doing all that crazy stuff. I am not sure if the computer monitors the actual fuel pressure in real time and makes changes based on that reading. That would be an example of Closed Loop Control (PID).

I hope this lengthy response helps you out and others that are going to experience this exact same issue in the future. Happy Motoring!
 












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