I’ve noticed what I can only describe as a shudder when my truck is idling. I took it to a shop where they ran some tests and claimed there were no misfires and that it seemed to be running fine. They mentioned they could feel the shudder too but said it was normal. That doesn’t seem right to me, but I don’t want to spend more money just to hear the same thing. Any thoughts?
I would check your air flow sensors and spark plugs first. They’re the usual culprits for rough idling.
Kelby said:
I would check your air flow sensors and spark plugs first. They’re the usual culprits for rough idling.
Thanks! I’ll check those out. Seems like something the mechanic could have looked into for me. Might be time to find a new mechanic.
@Torrance
Absolutely. A lot of mechanics today rely too heavily on code readers. They often follow the mantra ‘no codes, no problems,’ which isn’t a reliable approach. But I guess that’s just how it is now.
If new plugs and coils don’t solve the issue, check out videos on the weeping hole fix. I did it to my truck and it got rid of the rough idle.
I’ve had a 2021 3.5 EcoBoost since new, and it has always idled a bit rough too. No codes ever show up. Seems like it might just be a thing with these engines.
A worn motor mount could cause a rough idle without triggering a code 
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It’s normal for these engines.