2011 XLT 5.0 Coyote. There is without a doubt a problem, but three dealers don't seem to want to take my money.

Truck has a performance problem - it's missing almost unnoticeably at idle, but it's obvious (if you care to notice) when you hold the throttle barely open. Idle seems smooth, but if I hold it at about 1500 rpms, it most clearly and definitely is missing.

However, since there are "no codes" and since mode $06 (or equivalent for this year) shows "no misfires", none of the young folks at the dealers seem to think anything is wrong.

This really manifests itself when I'm towing a 6k pound trailer and the truck can't pull it up a 2% grade unless I drop it into 3rd gear.

Of course, if I drive it like a race car it's a beast. But I can't leave rubber at every red light, especially when towing.

Fuel trims look fine (ST bounces between -4 to +4, LT sits right at +0.5). Cleaned the TB. Cleaned the MAF. Brand new Motorcraft plugs gapped at .045. CHT sensors read 205 on one bank and 198 on the other. Coolant sensor seems find. Haven't done a voltage test, but TPS data in the OBD seems smooth.

No idea how to test the coil packs (neither does Ford). They want me to drop the $$ to replace all 8, but I'm not throwing that much $$ at a problem unless I can see real evidence a coil pack is bad.

I'm no novice however I'm losing my mind that "everything is normal" yet the truck so clearly has a problem.

This has been going on for months and I'm at my wits end. Fresh ideas, anyone?

 

I got the same problem with my 2011 5.0, slight miss while idling and definitely feels and sounds like misses around 1500 rpm- had to the dealer also told no problems. Did the plugs and fuel system cleaning, air intake cleaning, cleaned all that can be cleaned pretty much with no change. Its been doing it for a long time now though and ive given up, but if someones got an idea that would be great.

 

The coils at autozone are about 1/2 what they cost at the dealer.

One thing that wasn't mentioned on either post above me is the mileage on your trucks. When the plugs were changed, did the boots get changed as well? Sometimes the boots can crack and give a small symptom.

 

Sorry i meant to put the milage, i have 93000 now, i did the plugs at 75000. No i didnt do the boots or springs inside cause they didnt look to be in bad shape at all.

 

Good advice here...

 

I appreciate the idea. I will try this hopefully can get to it soon thank you.

 

Coil packs or COP (Coil On Plug)?

 

Sorry, for clarification they are COP.

 

Watch these two videos. He explains why it is so difficult to find a miss without it setting a code.