Rough Idle Woes and More

[Zatko]

First thing: I am not great with cars. My knowledge is limited, so please forgive me if I leave anything out that is important (and let me know!).

I have a 2004 ford explorer, v6 4.0, 2WD, with almost 100,000 miles.

After being a complete dolt and riding for over 6 hours (300+ miles) with overheating problems, I have had a laundry list of problems. Luckily, it seems I taken care of most of them: my thermostat casing cracked, along with shorting my temperature sensor, so I went ahead and replaced those. Spark plugs and wires have been replaced. Recently replaced the thermostat after a pretty decent radiator flush. After all this was done, my check engine light went off, as did my check gauge light. So no more overheating. Even the rough idle was diminished, but still there. I thought all was well.

Until today. My check engine light came back on (and with a vengeance - it's blinking now) and the rough idle is even worse. The engine is visibly shaking. I can take pics and a video if necessary.

I have had a diagnostic run by Ford prior to any of the repairs I mentioned. They said I had a possible cracked/blown head gasket, but obviously they won't know until they open her up. I'm trying to avoid that, so I wanted to take care of every other aspect first. Note: there is no mixing of water/coolant with gas, so I do not suspect a cracked block.

I have read that the rough idle could be due to a computer module (which one? I have no idea) needing recalibrating. After that, I read that it could be due to a vacuum leak between the upper and lower manifold halves, so some o-rings might need replacing. And one other thing I read was that it could be due to the PCV valve being melted/collapsed, causing some sort of obstruction. Honestly, I have no idea about any of these things. This was only from simply browsing some websites (mainly this one). I figured those were my 3 best options.

So I am going to bring her over to my buddy who has an OBD II reader tomorrow or on Saturday, and hopefully this should isolate my problem. If it doesn't, I am hoping that a few of you have some suggestions that may help me out.

Like I said before, I'm quite ignorant to many things auto-related, but I'm learning. Be gentle.

EDIT: I forgot to mention I have had some oddball problems with my AC/heat. It sounds like there are leaves somewhere in the system. When the AC is on, occasionally it will sound like leaves are rustling around (particularly around the passenger side airbag area), but it won't last long. The AC usually works no problem, but when the sound comes up, it doesn't work as well (i.e., the fan seems to have less strength), but then quickly fixes itself. I noticed that the heat wouldn't come through the air vents when I was having my overheating problem (I wanted to cool the car off so I turned the heat on). I don't know if the two are related, but I would imagine they are. The heat problem only happened once, and the AC problem has happened quite a few times.

 

[BIGTREAD]

well the heat not coming on could be simply low on coolant. Once enough has blown off from overheating, there isn't enough in the system to cycle through the heater core.

Ford idle issues...arg. The vacuum lines and the vacuum in general is ultra critical. One melted or cracked hose somewhere and the gig is up. Sometimes you can hear a leak by using a tube like aquarium tubing as a stethoscope. It's gonna take some systematic narrowing down to find the culprit.

 

[Zatko]

Found one line was not connected. My friend (who is more car savvy than me) said it was some sort of vacuum line, but wasn't sure what it was. I guess it was shook loose somehow.

Rough idle still happens, though. But not after start-up. The car has to be warm and then put into park for the roughest idle, but will still idle a bit rough at stop lights/signs (in 1st). The colder it is, the less the idle. Only takes about 5 minutes to warm up.

As for the coolant issue regarding the AC, I checked that a while back. It still has plenty of coolant and pressure.

And what do you mean by using aquarium tubing as a stethoscope? I have a fish tank, and plenty of tubing, so I'd like some more info on that.

 

[Exproblems]

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EDIT: I forgot to mention I have had some oddball problems with my AC/heat. It sounds like there are leaves somewhere in the system. When the AC is on, occasionally it will sound like leaves are rustling around (particularly around the passenger side airbag area), but it won't last long. The AC usually works no problem, but when the sound comes up, it doesn't work as well (i.e., the fan seems to have less strength), but then quickly fixes itself. I noticed that the heat wouldn't come through the air vents when I was having my overheating problem (I wanted to cool the car off so I turned the heat on). I don't know if the two are related, but I would imagine they are. The heat problem only happened once, and the AC problem has happened quite a few times.

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Under your front passenger side dashboard, behind the glove box is the outside air incoming duct work or air recirculation box and you may have gotten some debris or leaves down in there. It's common for stuff to get in there.
If your fan is blowing less air through your dash vents, you could have a failed "air recirculation door". That "air recirc door" is inside the "air box" that sits on top of your blower housing that is located directly behind your glove box. Open and press the plastic side tabs inward on your glove box and it will roll downward towards the floor for access. I recently removed that air recirc door in my Exp and once it was removed, the air flow to my dash vents greatly improved to normal flow. There are lots of posts on that subject in here and the repair instructions and photos to remove the failed air recirc door. Use the search function at the top of the forum to find that topic. Takes about an hour or so to remove the air recirc door. Once it is out, you lose the "Max - AC" cooling effect but your AC will still work, just not get icy cold.
If you aren't getting proper heat through your vehicle's heater core you may not have gotten all of the air of of the cooling system when you re-filled your cooling system with antifreeze, after you over heated it and had to replace the thermostat housing and components you mentioned. Try squeezing out the air in the system by squeezing the upper radiator hose numerous times when the vehicle is cooled down, watch for air bubbles coming up in the expansion tank. Also have the over flow/expansion tank cap off when doing this, but replace the cap prior to starting the vehicle up again. Then run it again and let it warm up to normal operating temp and turn on the heater, see what happens. Add more antifreeze if the level goes down in the expansion tank after doing this and fill to the full level mark on expansion tank. If you do get heat but just no air flow thru the vents, then your problem is that air recirc door mentioned above in my post. It will affect both heat and AC vents when either option is activated. Good luck.

 

[Exproblems]

And what do you mean by using aquarium tubing as a stethoscope? I have a fish tank, and plenty of tubing, so I'd like some more info on that.

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He means stick the tubing in your ear! : LOL Use the aquarium tubing like a Doctors stethescope and one end of it goes in your ear and the other you press against the vacuum lines and listen for a leak or hissing sound while the vehicle is idling/running in PARK. Move the tubing along the length of vaccum hose as you go from one end to the other or as much of it as you physically can. "Hissing" sound will mean a leak in a rubber vaccum hose, replace it. Vaccum leaks can be hard to find.

 

[BIGTREAD]

yep.thx