Stuttering at 1,600 rpms

[Postal_Dave]

My 1996 Explorer 4.0 XLT stutters at 1,600 rpms. It's fine at 2,000 rpms. It's fine when it idles. However, when trying to maintain speed and I'm giving it that little bit of gas to keep it at 45mph, it stutters. By stutter I mean the vehicle vibrates like I'm riding poorly tuned motorcycle.
I've been chasing codes, the first was O2 sensor on bank 2, upstream. So I replaced that and cleared the codes. This didn't stop the stutter. The next code was the EGR valve. Changed that and cleared the codes. Now I'm getting that cylinder 3 is having misfires.
I fix one thing, then another code comes up and I'm still having the same problem. I know that there is a cylinder that misfires intermittently, I just don't believe that is the reason for the stutter at 1,600 rpms.
BTW: I don't know if this will help, but on the last fill-up, I got 10mpg.
Thanks for reading and for your advise.
Dave

 

[Fix4Dirt]

if you kick it down a gear is it alright? is it fine at 1600 rpm in a different gear/without torque converter locked? could be TC shudder maybe if its consistent when tc is locked and not stumbling when you cruise off the line in 1st at 1600

 

[Fix4Dirt]

heres a good link Torque Converter Shudder

 

[C420sailor]

If you don’t have Forscan, I recommend you get it.

That way you can record live data of the shudder and play it back. I’d pay special attention to misfire counts, EGR valve position, O2 sensor data, fuel trims, etc.
My mom’s expedition had a miss at 1500rpm that happened to coincide with the EGR valve commanding open. Disabled the valve, miss vanished—bad valve confirmed. Not saying that’s it, just an example of how good data can help.

Any hard starting? What’s your ECT and IAT reading? 10mpg is pretty damn rich…

 

[Postal_Dave]

I drove it today in low 2 and it still shuddered at 1,600 rpms. Then I shifted to Drive, with the O/D off and at 1,600 rpms it shuddered. The engine was was mostly at at 2,200 rmps to maintain speed (50-55mph) but there wasn't any shutter at that rpm. When I turned the O/D back on, the shutter was back and still at 1,600 rpms.
The check engine light started to flash so I had advance auto use their scan tool. It only had that cylinder 3 misfire on it.

 

[C420sailor]

Last time you did plugs and wires?

 

[Postal_Dave]

Plugs and wires were done less than 40,000 miles ago. But that has also been about ten years. My Explorer is usually driven only 10 - 15 times a year when I need to haul something, or my daily is in the shop. I'm going to buy the plugs and wires today and put them in soon.

 

[Fix4Dirt]

a bit late, but iirc on my sohc egr opening is commanded around 1700, so not too far off from yours... could potentially be thet too! could injector be stuck? have you tried swapping coil pack banks/?

 

[Postal_Dave]

I'm fixin' to get ready to change the plugs today. If I still get the misfiring code of cylinder 3, after I change out the plugs and wires, then I'll change out the coil bank. I feel like the Explorer is throwing one new code after another just to keep me busy, or just to get attention. lol

 

[Postal_Dave]

OK. After chasing codes from O2 sensor and EGR valve, it said that Cylinder 3 was misfiring. So I bought an ignition wiring set and 6 new plugs. I just replaced the plug in cylinder 3 and it's wire to see if the codes would finally clear and they did. The shudder at 1,600 rpms went away too.
Yipee!
So I decided to finish changing out the plugs and I broke the plug for cylinder two in half. It's flush with the block too. LOL Can't do anything but laugh in that situation. With it being right next to the A/C stuff, I don't know yet how I'm going to get to it, but that's for another thread.
Thanks everyone for their help.
Dave

 

[C420sailor]

****.

Some guys have had good luck with a properly sized (big) easy out. I’d spend a good while heating and soaking the nuts off that stub though.

Vacuum/blow out the jug as best as you can when you’re done. If you have a borescope, check it. Small bits of ceramic will be fine, get as much metal out as humanly possible