OK everyone I need some help here. I'm going to try to describe what happened twice in a long distance trip in my F1 50. First, I'll say that it's got a Livernois tuner in it. I have never had a problem with Livernois tuners and I've had them on several cars. In this occasion I had a 93 octane performance tune I had about 200 pounds of gear in the bed of the truck two teenagers in the backseat and another parent in the front seat. 35 gallon fuel tank was full, So, probably more weight than I usually would have. The first time it happened I was slowing down at the stop light then the light turned green and I slowly started to accelerate the gears were lugging and as I depress the gas further the transmission started to downshift. Right at that moment I also heard a rattling as though a rock was banging around inside the engine block area. I thought maybe in fact it was a rock that maybe got caught in the tires and flipped up into the wheel well. However, it happened a second time the following day in the same circumstance when The engine was lugging right before it downshifted and as it downshifted I heard the rattle. Anybody have any ideas what this could be?

 

Sounds like maybe knocking/preignition.

 

+1 on the knocking/preignition. Seems like your tune is a little too aggressive with the ignition advance and too slow to dial it back at low rpm/high load.

 

I like the part where it sounds like a rock banging around inside the engine! Ford designed a Sport Mode for their truck buyers, likely to reduce owners from installing a custom tune on their engines. Be that as it may, enough is never enough! Perhaps uninstalling your custom tune, and putting your truck back to stock may help? And just cause the fuel pump says such, doesn't mean someone didn't make a mistake or the blend is a combination of winter or summer fuel. Sometimes running on the edge, one can occasionally stumble and fall.

 

Glad this was brought up, as this has happened to me a few times, mainly going up a small incline. As the truck begins to slow down and I depress the pedal to sustain speed, it begins to lug on me, like its in to tall a gear and I too hear an obnoxious noise (as described) before the trans shifts down to accommodate. The trans is not downshifting quick enough for some reason. Stock tune. Best example is, as with a manual trans, going up a hill in wrong gear, lugs on ya to shift to lower gear.

 

That's why I usually turn on tow mode when in that kind of situation. Slightly more aggressive in the shift department.

 

So its not really anything to fret over? I'll give it a try. Usually happens where I get gas sometimes, got a slight incline leaving the locality.

 

No more than a little man in the combustion chamber beating on the top of the pistons with a hammer. Just don't allow it to go on too long.

 

I changed the tune to a 93 tow tune and the problems went away.

 

Sounds like low octane knock.

Change where you purchased your last gas fill up and make sure it`s 93 octane or higher.

 

Makes sense. A tow tune expects high loads at low rpm's and large throttle openings and a slower increase in engine speed. Remember the good (??) old days of carbs and distributors with vacuum advance diaphragms? At large throttle openings and low engine speeds there was no vacuum to advance the timing. As rpm's increased so did the manifold vacuum and along with it the timing advance. Now we have the software version of all that plumbing.

 

I have the same problem with 5000 miles and I was told I need new spark plugs. Not sure that is the solution.

 

Are you saying that you have a new vehicle with 5K on it that knocks? Who told you that you need new plugs? The dealer? I've never heard of a modern engine needing new plugs after 5K unless detonation was soooo bad it destroyed a plug in which case you'd probably have holes in the pistons too.

 

My truck is a 2015 Ford F150 3.5 Ecoboost with 5000 miles that I bought new, first they had to replace the canister vent solenoid cause the engine was running rough and was getting terrible gas mileage, then this shuddering/rattle started going up incline around 25 mph hour, only time it does it. When I took it in the service manager said I needed new plugs, I replied it's only got 5000 miles on it. Whatever it is it should be covered under new car warranty, still have another year left.

 

Since you guys are ecoboost, spark plug changes are in your immediate future. The change interval is only 30k miles and gap is finicky at .030. Also, drill your 1/16" weep hole in the intercooler... it will save you headaches later.