2011 Explorer - Stumbles uphill

[PAFirefighter81]

Hi all,
Recently purchased a preowned 2011 Ford Explorer Limited with approx 110k miles on it. Started having an issue when going uphill only. When the Ex is on level ground, has great throttle response and takes off. When you start to climb a hill (no matter the % of grade) the Ex starts to stumble like it doesn’t have the power to make it up. If you floor the accelerator, it will then pickup fine and climb.
Had a power flush done on the tranny thinking it was beat fluid. The tranny shop said it was about 1.5 quarts low before they started. He flushed the system and filled with fresh fluid (kept the old for me to see). It was the color of old motor oil (black). Then dropped it off at the mechanic we use and had a full tune up done.
Took the Ex to NY this weekend thinking we were good to go. Got to the mountains in Scranton, PA area and that’s when the stumble came back and more pronounced. While climbing the mountain, I floored the accelerator like usual but this time the RMPs rockets to 5k, no power or throttle response, and the CEL flashed for about 20 secs. Once I peaked the mountain, she flew down like nothing was wrong. Checked it today, and no codes stored in the memory. I’m at a loss......

 

[KayGee]

I'd try a different scan tool or forscan. If your CEL was flashing, there should be something to review (likely multiple misfires on one or more cylinders).

What was involved with the "full tune up" that your mechanic did?

 

[PAFirefighter81]

I'd try a different scan tool or forscan. If your CEL was flashing, there should be something to review (likely multiple misfires on one or more cylinders).

What was involved with the "full tune up" that your mechanic did?

KayGee, I pulled out the laptop and ran the scan program on there. It did show a P0301 as pending. I have called the mechanic to find out what was completed for the tune-up. Will post back from the mechanic

 

[PAFirefighter81]

Mechanic changed all the plugs, air filter, oil, oil filter. I just spoke to him and he said one of the plugs was really fouled. When I asked which plug, he said they believe it was #1. I’m thinking fouled plug called for more power from the coil causing the coil to go bad due to the more power needed for spark

 

[KayGee]

To me a "full tune up" should have included a diagnostic scan which probably should have shown the same pending code and/or misfires that should have prompted the mechanic to do further investigation. Did the tranny shop do any diagnosis to verify what they were doing would resolve your stumbling problem?

P0301 is cyl 1 misfires, so that would be a good place to start. You can test the COP, swap it with one from another cylinder and see if the problem moves with it (bad COP) or stays (look at fuel issue), or just replace the COP since they are pretty cheap.

 

[PAFirefighter81]

Did the tranny shop do any diagnosis to verify what they were doing would resolve your stumbling problem?

KayGee, the tranny shop did some research online and said with the fluid that color, it could be causing the torque converter to unlock in the RPM range. They were thinking build up in the valve body could cause blockages and a power flush would help push everything out. When the wife drove to the mechanic for the tune up from the tranny shop, she said it seemed to shift better and was a little more “snappy”

 

[KayGee]

It has been said that Mercon LV fluid can discolor rather quickly, so fluid color is not a good indicator to judge replacement. Either way, that is neither here nor there as you have a vehicle with 110K, so it may have been past due for a fluid change anyway.

Good luck getting the rest sorted.

 

[peterk9]

KayGee, the tranny shop did some research online and said with the fluid that color, it could be causing the torque converter to unlock in the RPM range. They were thinking build up in the valve body could cause blockages and a power flush would help push everything out. When the wife drove to the mechanic for the tune up from the tranny shop, she said it seemed to shift better and was a little more “snappy”

Welcome to the Forum Leon.

Peter

 

[PAFirefighter81]

Welcome to the Forum Leon.

Peter

Thx Peter