LeeG

I have a 2010 F-150 Supercrew with 120K miles. Recently I have been experiencing rather severe stuttering and lurching during heavy acceleration from a stop. It almost always occurs when getting on a freeway at an on ramp that has an incline. If I hit the gas hard to gain speed, it happens. If I gradually accelerate, it does not.

Things tried so far:
New plugs
New Fuel Pump Relay
New Fuel Pump and Filter

My mechanic and I are both stumped, so hoping for some insight as to what to try next.

Thank you
Lee

Spanky666

Sounds similar to a sparkplug wire shorting out against the block. How old are the wires?

Check ignition coils. You can check for spark by running the truck and pulling the wire out of the coil abt 1/2", you should hear a POP POP POP POP POP like a taser arcing. Do that for every wire one at a time to verify spark at each wire first. Becareful to keep your hands and fingers clear of the arc. No more than 1/2" lift off

andyzonneveld

do you notice the CEL (check engine light) flashing during this acceleration? if so you have a misfire. Misfires could be due to bad COP (coil on plug). I see you didn't change those when you put in the new plugs. Get yourself a code reader and check for pending misfire codes. If nothing pops up on code reader, you could have a slipping transmission.

LeeG

Andy,

They changed the boots on when they changed the plugs.

Spanky,

I have not tested that they are firing, but when I asked my mechanic about it, he said that if that was the case, we'd be getting a check engine light.

I am not getting a check engine light at all, even when it is happening. It also happens when just sitting parked. If I hit the accelerator, it does the same thing as the speed ramps up. It seems pretty much ok, at a constant RPM, but definitely will sputter when increasing.

Lee

RLXXI

What brand plugs did you use? Have had a lot of issues with anything other than Motorcraft over the years. Autolite plugs are the worst.
.

LeeG

I believe they used Motorcraft. The problem predated the plug change. It was nearing time to change the plugs, so we swapped them out before trying anything else.

Spanky666

Maybe a long shot but, my truck has 200k + miles on it and the valve stem seals went bad. Worn out, hard as plastic (theyre rubber), and was sucking oil into the combustion chamber. I would have to put 5qts in every 2 months. Messed up all my cat converters, but did the same thing. Loss of power on acceleration, occassional stall outs. I could not for the life of me find the problem. Swapped literally every sensor under the hood. $3000 into it I realized it was the valve stem seals which im told go bad around 150k-175k

LeeG

Problem is finally resolved, so I thought I'd summarize the whole thing thing here in case it helps someone in the future.

Initial problem was strong shuddering/shaking during acceleration. The problem could be duplicated just sitting in park and pressing the accelerator, so that ruled out a transmission or drive train problem. I was not getting a check engine light at any time - not even a flicker.

The plugs were due for replacement, so those were changed out. When that didn't fix the problem, it was road tested while being monitored, and they saw some pretty drastic fluctuation in the fuel pressure, so they replaced the fuel pump relay, and then the fuel pump itself.

Neither of these fixed the problem so they then performed a back pressure test, and it passed, but they noticed the gauge was bouncing severely, so performed an exhaust back pressure test. A few cylinders showed loss (#5, 11%, #6 9%, #7, 3%, #8 4%), but all were within spec.

I then took the truck to a Ford Dealer, and they pulled the following codes with their IDS
P0012 - Intake camshaft position timing - over retarded (bank 1)
P0022 - Intake camshaft position timing - over retarded (bank 2)
P0346 - Camshaft Position Sensor Circuit A (bank 2)
P0341 - Camshaft Position Sensor Circuit A (bank 1)

Based on this, they recommended replacement of VCT solenoids as per TSB #14-0114

This was completed, and the truck ran worse than ever. The next day after this was complete, I finally got a check engine light, so I took it back in to my mechanic and they pulled the following codes:
P0150 Bank 2 Sensor 1 (Hard)
P0130 Bank 1 Sensor 1(Pend)
Based on this and monitoring of air fuel ratio sensors, the recommends replacing both Upstream Air Fuel Ratio Sensors.

The problem was better, but not completely resolved. They did an extended test drive with the scanner running, and didn't pick up error codes, but did detect possible issues with the Mass Airflow Sensor readings, but no codes from it. They replaced the Mass Airflow sensor with a new unit, and all running issues went away.

I have no idea how many of the above repairs were not needed, but at this point, I am just happy to have everything working again. I hope this helps someone else in the future.

Thank you to all who took the time to look and offer advise. It is much appreciated.

Lee

chickenwire

Thanks for closing it out with the final fix! Goes a long way for anyone having the same issue in the future.

proud2bcanadian

Lee,
Was hoping to see if you could provide an update on this. Are things still good now? My truck has started doing this exact thing and it's worrying me because I just put $6k into new suspension, brakes, tires, and some smaller bits and pieces.

Thanks!