FX414'

Hello all,

New here, but have owned my 2014 F150 5.0L 4X4 for about 4 years. So to begin, I am the second owner of this truck. Has a clean record and all maintanence is kept up with religiously. If not done by me, its done by a Ford dealer. When i purchased the truck, it had 68k miles on it. I now have 139k on it. Ever since iv owned the truck iv noticed its had a surgy idle when in gear also kind of a rough idle when in park and sitting. For example, while at a traffic light or in traffic. Truck is at operating temp, foot on the brake creeping up slowly to the light or following stop and go traffic, you will feel a surge or pulse equal to that of the engine RPM (its like you can feel each compression stroke). The pulse/surge gets wores with the A/C on. There are NO CEL illuminated. IF you put the transmission is 2nd and allow it to creep, the pulse/surge does not appear at all???

Figuring it needed a tune up, I did the following:
* Spark Plugs Replaced
* PCV Replaced
* Air Filter Replaced
* MAP sensore cleaned
* Throttle body removed and cleaned with new gasket
* Disconnected battery to reset PCM

Still no change in correcting the problem, kinda figured at that point, since there were no CELs, that that was just the nature of that engine (characteristic). So I drove it for about 40k miles until it started getting noticably worse.

I finally took it in for them to diagnose and repair. I also had them change the transmission filter and fluid. During the diagnostic report... I was told that there were "pending" codes of a missfire. As the service tech said " I had cylinders breaking down". They were going to do a tune up, but i had informed them that I already performed a tuneup with new plugs 40k miles ago. After me telling them that, they dug into it deeper and found that i had three faulty injectors. While they were in there I had them replace ALL injectors with new. When I got my truck back I had noticed they replaced three coil packs as well. I hopped online and ordered 5 more Motorcraft coils so that i would have all matching set AND replaced the spark plugs yet again. So it now had new injectors, coil packs and plugs gapped correctly. Well the problem was still there. I will say I noticed my average MPG increased from 16.9 to 17.7 so i knew there was a change in performance, but still could not figure out why it still surged/pulsed while in gear AND had a rough idle??? I took it back to the dealer and they ran another diagnostics on it without any new pending codes. The next step they told me to do was to find another truck of the same kind (engine, year. ect) and replicate the situation to see if that truck did it.

So last week a contractor i know allowed me to take a spin in his 2013 F150 STX with the 5.0L with 196k miles on it. I immediately notice his idled smoother then mine AND his DID NOT surge/pulse like mine does in gear. So now I have an "apples to apples" comp. Either something else is going on that has not been detected yet. Or my truck has its own characteristic.

I did give it one last ditch effort to diagnose and fix. I just replaced the EVAP purge solenoid, for those have been know to cause problems. Again... no difference. At this point I think iv exhausted all SIMPLE possibilities that it could be.

Kinda at a lose now. Is it engine related? Or transmission related. I just reset my Average MPG last week and im currently averaging 18.8MPG Highway. The transmission does not slip or shift roughly.

Im thinking my next course of action is a compression test on all cylinders? Maybe I have a weak cylinder?

Does anyone out there with the same configuration as me experience this phenomenon? If not, are there any technicians that have run into this before??

gDMJoe

Vehicle Information Engine? Year? "configuration as me"

Check for a vacuum leak?

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FX414'

Thanks, just updated.

Im not sure on how to properly look for a vacuum leak, unless i break down and buy a smoke machine. I would have thought on a vehicle as sophisticated as this... that if there were a vacuum leak, that it would trip a CEL?

Dustodustrider

Also maybe check the evap canister purge valve ( but usually that leaves a CEL)
I see you removed and cleaned the Throttle Body but did you do the proper TB reset proceedure, my 5.4 surged and hunted until I did it just this way ; I haven't heard of it on Fords but my Chevy TB developed an intake leak at the valve pivot bushings
I have had good success at finding vacuum leaks using a piece of 1/2" PEX like tubing with a small funnel at the ear end as a stethescope to listen for the hiss, sometimes you can hear it by naked ear as the motor shuts off at the very end

Spiky

Unplug the MAF sensor and drive for a few miles to see if it changes.

FX414'

You know... I thought about a possible throttle body leak... When you say 'Pivot Bushings", are youtalking about where the shaft goes into the housing? If so, i thought about checking that.

When you TB leaked, did it trip a CEL?

As for as the Throttle Body relearn. I did discounect the battery for 2 hours. Then hooked it back up and followed the procedure for the relearn. Is that not enough? is it needed to jumb the negative and positive??? Iv never seen anything in a repair manual or owners manual to do that

Spiky

That was plenty of time unhooked to reset the computers.

13fx4150

I thought disconnecting the battery does not wipe out data? You’ll have to manually do it via forscan.

FX414'

The truck goes in tomorrow for state inspection and emissions. While they have it, iv asked them to perform a compression test on all cylinders and investigate the situation further. The service tech witnessed it via test drive and he even says "that very weird".

So we will see what becomes of this.

As far as the reset for the throttle body, i will ask a tech tomorrow when i drop it off.

Spiky

It wipes out Keep Alive Memory. Not all memory. There is a lot of drivability data that is cleared. For instance, the learned portion of the trans shifting strategy.