2015 3.5 Ecoboost has 1200 miles. I'm getting a low rpm miss. I can feel it and see the instant fuel economy gauge fluctuate when it is doing it. Not sure if it's weather or fuel related maybe. It's gotten colder and has been raining a lot and it all started about the same time. Fuel economy has dropped off some and it doesn't seem to have as much power. Doesn't seem to do it at full throttle. Also had a pretty significant surging about mid to 3/4 throttle getting on the highway. Any idea what's going on and how to get it fixed? I'm pretty sure if I take it into the dealer and there are no codes they'll just say they can't duplicate the problem.

 

It should have captured codes that they can find.

 

I had what I thought was a misfire on cold starts on my '13 since it was new. Took it to the dealer, and they kept it for almost a week trying to duplicate the symptoms. They even connected the PCM and watched as no misfires were recorded. Turned out to be nothing at all, I traded the truck a year later and it was running great.

My point is that the electronics on these things are very sensitive. You may have pending codes in the PCM that won't set the light yet. I'd suggest getting it looked at, but if no codes and they can't reproduce it there's not much they can do.

 

Both my '11 and '13 ecoboosts had a slight miss at idle.

 

My '15 misses at idle.

 

This isn't at idle. This is when you're cruising along at low rpm light throttle.

 

Hello
I was wondering if you've made any progress diagnosing your problem? I have a 2011 F250 6.2L that sounds like it has the same symptoms. In my case I'd actually describe the main symptom as a shudder, though I think the cause of the shudder is a misfire rather than something mechanical.

In my case, it shows up right about 1400 rpm, particularly in 3 or 4. Light acceleration is what makes it really show; if you accelerate harder or let off, it stops immediately. Tapping the brake has no effect (supposed to drop out TC).

I have COPs, plugs, wires on the way as I just can't find anything else that looks suspect. Have you carefully cleaned and inspected your COPs and wires?

Thanks!

 

Interesting. We get no miss at idle or any other speed. When it idles, the tachometer sits absolutely motionless on 600 rpm. No wavering, no miss.

 

The PZEV (Partial Zero Emissions Vehicle) and ULEV (Ultra Low Emissions Vehicle) engines are set to idle with such a lean fuel mixture on cold starts, that they are always on the edge of misfire. That may be what you are noticing.

 

That might explain it. I haven't checked to see if there are any codes, but the light hasn't come on.

 

Interesting. I always heard a light misfire on my '13 upon startup. Left it at the dealer for almost a week and they never were able to duplicate the problem. Picked it up and never worried about it after that. Haven't noticed that on this truck.