Troubleshooting Question

[feral]

My auto service days are long past, so I humbly call on the OSA experts with a somewhat puzzling question. One of our vehicles is a 2013 ford edge, 3.5 L 6 cyl, with about 140,000 miles. Under moderate acceleration there is a bit of a stuttering that seems like a plug issue, clogged fuel line, something. It isn’t noticeable under stronger acceleration. One ford dealer was unable to diagnose.

Now, the real question of this post. The issue is less noticeable when using higher octane gas.

Any thoughts?

Wife's cousin paid for 3 new transmissions before asking me, and I asked flat out if she buys the cheapest gas:
"I don't believe in that octane stuff."
I told her to try it for 4 tanks and see if it was still stuttering.
Issue gone.

 

[Nate08chevy]

Check engine light on? Ford dealer say it was throwing any codes? Is there any “rattling” on start up or during the moderate acceleration?

Timing chain and/or cam phasers been replaced during the 140k mikes? My vote is the cam phasers are on their way out and not controlling the timing correctly.

Or faulty knock sensor causing the timing to back off? Upstream o2 sensors reading incorrectly? Could be any number of things…

 

[Catt57]

Have you checked the fuel filter?

 

[turkeyrun]

Daughter had a Fusion, 135k, she mentioned stuttering issue under acceleration. I thought plugs and coils.
Cam phaser died and destroyed engine.

Good luck.

 

[capnkirk462]

Moderate/light throttle acceleration hesitation/stumbling is a classic symptom of coils that are on their way out. If they weren’t changed when the plugs were done, they probably need to be done. Personally, I do the plugs and coils as a unit—you have to pull the coils to pull the plugs, so it’s just as easy to put new coils in with the new plugs.

FWIW, my truck got well over 100K miles (I want to say it was closer to 150K) on the factory plugs and coils, but the new (OEM) coils started stuttering after something like 30K miles. The replacements for the second set are still going strong.

My motorcycle did this would stutter/bog down at the 1750-2000 rpm range. Fine at all other rpm ranges. Went online and the forum said it was the coil. Replaced the coil and it went away. Acted like fuel/electrical issue. Most of the times coils just die and leave you stranded.

 

[trekrok]

My next stab at it would be coils. CEL should catch a bad one, but I've had them go bad and not set any code.

 

[jeepjackazz]

If its a misfire it should be easily viewable under driving conditions with an ids scan tool, or any half decent aftermarket tool. before throwing coils at it, id recommend getting it looked at to verify that it is in fact a misfire, and when a suspect cylinder is located, rotate that coil to another cylinder and see if the miss fire moves holes. Power balance is the term for this under ids (factory tool) and should be similar on any other... miss fire monitor, which cylinder is misfiring etc...

 

[BillM]

Wife's cousin paid for 3 new transmissions before asking me, and I asked flat out if she buys the cheapest gas:
"I don't believe in that octane stuff."
I told her to try it for 4 tanks and see if it was still stuttering.
Issue gone.

I buy the "Top Tier" no-ethanol gas at On Cue. My beater 98 Silverado started getting 15mpg instead of 11 or 12. It's what was specified for the Elantra. No longer have any of the Elantras or Accents, but still have that beater Chevy. And a slightly newer 08 Uplander. It was getting 16mpg with three truly beat up plugs in the rear bank until I paid someone else to replace them. Now it's doing nearly 18mpg. 5.7L V8 in the PU, 3.9 V6 in the minivan.