1999 ford explorer 4.0 Soch rough idle

[Mumbler57028]

Ok I know this is a topic that is really played out but just bare with me.

I acquired a used 1999 explorer. Had some issues but I figured they where minor so I went with it. It idled very high from the get go. About 1500 to 2000 with my foot on the break. And it would stall like it's running out of gas after 30-40 min of driving. Then I would have to let it sit for 15 min for it to start again.

I got lean codes bank 1 and 2,

So I started researching the symptoms. I read that it could be vacuum leak and or fuel system issues.

I started to inspect and found lots of things that could be the culprit.
1. My iac valve was unplugged. Replaced it. No fix
2. Leak in the upper intake manifold. Replaced upper and lower gaskets. (Lower idle but still high with surges)
3. Fuel pump was converted to an external pump and was being powered by a piece of extension cord ran to battery and fuse box. ( I really got a kick out of that one!!! Haha) replaced it with the proper internal system.
4. A hose going down from the PVC valve was broken and rigged with a hose of smaller diameter as an adapter or extension. Replace the valve and three hoses that connect to it.

Now it runs a lot better but still has a idle surge when slowing to a stop. The rpm will jump like the computer is searching for something. Also does it repeatedly after I reach above 55 mph with my foot off the gas.
And when I'm in drive or reverse at a compleat stop it will bog down and sputter. It's weird though, it only does it in drive or reverse at a compleat stop. Neutral or park runs and idles perfect.

Any ideas? I need to put an end to this debacle.

 

[Mumbler57028]

...

Also when in drive and at a stop with my foot on the brake, it sputters and idles at 500-600 rpm it kind of pulsates up and down but never shuts off. What it the normal idle? It has to be something really small at this point. I've already replaced all of the more costly things that could cause this.. Fun fun she's still pretty awesome though.

 

[2000StreetRod]

torque converter locked?

If the brake pedal position switch isn't working the PCM won't unlock the torque converter so when the vehicle is stopped the engine has a tendency to stall. An easy way to test the switch is to set the cruise control and then tap the brake pedal. If the cruise control doesn't disengage the brake pedal position switch isn't working. The switch has two circuits: one for the brake lights and one for the PCM/cruise control.

 

[Mumbler57028]

When I set cruise control and tap brakes it disengages. I'm leaning towards dpfe sensor, erg valve or maf sensor? Could bad plug wires cause this? The only trouble codes I've gotten where bank 1 and bank 2 lean and iac valve which I previously replaced. I'm stumped..

 

[drdoom]

I had a similar problem once, turned out I had popped the hard line off the IAC tee while doing some other work. Also I am suspect that the idle screw on your truck may have been tampered with. The plug wires you can check them with your meter. Same for the DPFE. And I would do an electrical test at the IAC harness, and the TPS as well. Those are easy things to eliminate. Almost everything can be tested with simple tools and a shop manual. Putting MAFs and IACs on is not cheap. I really think you have a vacuum leak.

 

[Mumbler57028]

Ok so I have a new idea... Maybe it could be a problem with the throttle plate sticking, tps sensor, idle adjustment, or lose throttle cable.. Wile in drive or reverse at a compleat stop it will bog down. But if I put my foot on the gas ever so slightly (just the weight of my foot no pressure) it works great. I'll test all the electrical stuff when I get to work Tuesday where I have my tools.

 

[wbdavid]

Mine was doing this last year after looking all over for vacuum limes loose changing fuel filter having fuel system flushed. It was the maf the whole time. I cleaned it with the cleaner for it has run good ever since.