runs poorly under load, sputters at idle

[jimcollison]

Hi guys. I'm new here and am in dire need of advice.

I have a 99 explorer 4.0 SOHC with 160k miles. A few month ago i ran out of gas (doh!) and have been having trouble ever since. It started with poor idle. Most of the time I'd have to keep one foot on the gas to keep it from dying. I also was experiencing some hesitation and lack of power when accelerating. I changed plugs, wires, fuel filter, cleaned the injectors and changed the idle air controller. After that it idled fine but continued to sputter when accelerating or going up a hill. I've checked for vacuum leaks (with a can of starting fluid) and didn't find any. The cat converters sounded like a box of metal cherrios when pinged with a hammer so what the heck, i changed those too. That didn't fix it and the problem is getting worse. It now sputters a little at idle and runs like a piece of junk when accelerating. Also, I've had the MIL come on and flash a few times and today it came on and stayed lit. I scanned it and pulled a code for cylinder 2 misfire.

I'm not sure what to do now. I was thinking it might be the fuel pressure regulator. I've tested the fuel pressure and it reads a steady 65psi and doesn't move when i hit the throttle. Haynes manual says that the fuel pressure should be at 30-45psi at idle. Part of the problem though is that both Haynes and Chilton make no mention of a returnless system and I'm pretty sure that's what I have.

Any thoughts??

 

[my98nnj]

It's probably not fuel related, running out of gas doesn't cause issues, normally. People do it all the time.

I'd check ignition wires, coils and plugs.

 

[jimcollison]

Can you give me any more insight on what to look for on the coil? I'm guessing i need to pull some connectors and test resistances. Tomorrow I'm going to tear in to it a little more and see what i find. I'll also pull the spark plugs and see how they look and just replace #2 since that's where the misfire was.

 

[chapsdeva]

Definitely pull that plug and replace with another if you have available. I had a cracked plug on an old Civic that had many of the symptoms you describe. Check the condition of the plug wire as well and make sure the connection with the plug is not loose.

 

[jimcollison]

Just an interesting note-

Last night i was screwing around under the hood and moved around the spark plug wires going to 1, 2 and 3. Some of them were touching eachother and i was a little worried about current crossing between wires. (note that when i replaced the wires a couple months ago i bought the cheapest ones). This morning when i drove it, it ran a heck of a lot better. I was amazed! However, after about a half hour of driving it started to run poorly again and continued to run like crap for the rest of the day. The problem has never been intermittent like this before.

I'm about to head up to the parts store to get a new plug for #2 and some spark plug wire spacers. We'll see how it goes.

 

[ranger7ltr]

After running out of gas did the station you got fuel from recently have a flood or some other water related problem? It sounds a lot like my truck.. I topped off after changing the fuel pump in the 99 Sport and it has run like crap ever since..
I pulled a sample of the fuel after changing the fuel filter and half of the fuel I pulled had water in it.. The gas looks murky...Like it had dirt and water mixed with a little gas....

Pull a sample of the fuel in your tank and see what it looks like.. You might be surprised...

 

[jlsparky7]

Check for little pin holes in the spark plug boot. That can cause a false ground.

Run a can of seafoam through it 1/2 tank 1/2 vacuum line. There is a how to in the link in my signature.

Buying cheap plug wires is usually a bad idea, you might want to upgrade to some quality wires.

As for whether or not you have a fuel return look next to your fuel filter. There should be 2 lines if its returnless (1 fuel 1 brake) and 3 if it is a return system.

 

[nitro71]

ranger might be on to something here. Did it start immediately after leaving the gas station? I filled a buick up one time, got bad gas and didn't even clear the lot before it drove really, really bad. Had to change the fuel filter out.

 

[jimcollison]

It's fixed! Last night i pulled the number 2 spark plug. the ceramic had two big cracks in it and one of the cracks has a frickin lightning bolt burned around it. It looks pretty cool actually. Anyway, I put in a new plug and it ran like to good ol' days.

Lets reflect- Don't ever make any assumptions when working on a car. I assumed that since i had changed the plugs a couple months ago that they were fine. That might be the case most of the time, except when you over tighten and crack one. I spent a lot of time scratching my head on this car and a lot of needless repairs. All for a $3 spark plug.

Thanks for all your help guys!

PS- wtf is up with Haynes and Chilton manuals not even mentioning the returnless fuel system? I was seriously ready to pull the upper intake to replace a fuel regulator that I don't even have. That would have been sweet.