Well, I finally got my paws on a Ranger. Unfortunately, a few days after purchasing it and driving it around, I've come across a problem that my mechanic cannot figure out. He's had it in the shop with his guys for a month now. I'm going to have to take it somewhere else, but I'd like to know if any one around here has any clues as to what might be occurring or has experienced a similar problem. Forgive me for my terminology -- I'm a computer geek, not a mechanic!

2011 Ford Ranger Sport V6 4x4

Description of Problem:

When engine gets to operating temp (temperature gauge directly in middle), truck will have seemingly random engine power loss under load. Must be in gear for problem to occur. Will not happen in idle or neutral according to last garage. No shudder or engine noise. Lights/radio/fan stay on, power steering stays on. RPMs drop, no response on gas pedal. Comes back after anywhere from 2-5 seconds. Issue is not present when engine is cold, only happens when fully warmed up. Will occasionally stall outright and suddenly when stopped at a red light, in gear. The only thing that was done between it operating fine and not operating was that I pulled a single fuse out of the passenger foot well panel (4x4 fuse) to see if it was in tact because my 4x4 was not working. That issue turned out to be a transfer case motor and was fixed promptly.


Work completed:

• spark plugs replaced
• decarbon (chemicals in throttle body, fuel additive)

Problem still occurred. Prior to replacing spark plugs and decarbon treatment, the engine would outright stall and require restarting. It now comes back on it's own still in gear after a few seconds, no outright stall. Previous shop describes it as 'losing spark' and could not determine the cause.


Swapped for testing:

• inside fuse box (corrosion found)
• crank sensor
• throttle position sensor
• idle air control valve

Inspected:

• grounds
• O2 sensors
• fuel delivery (never skipped a beat)
• Coolant temp (within range)
• Did not swap coil, but wet it down and nothing
• connections at computer
• under hood fuse block
• did bunch of wiggling and tapping of units
• watching scanner to see what kicks out (nothing registered, it happens too fast, no codes. KAM error, however)

He's at a loss and not sure where to go from here. He suggested I run a few tanks of fuel through it to see if the problem goes away, or if it gets worse. I'm obviously going to have to take it somewhere else to be looked at, however, the mechanic is up for any sort of suggestions of things to try that he may have missed.

 

Compression Test?

 

"No cylinder misfires, therefore no need for compression test. Runs way too good for poor compression!" -- My Mechanic, when asked if he did that :) 151,000km on engine. He suspects the computer, however isn't 100% confident and doesn't want me to drop $1200 for no reason.

 

Welcome to the forum

No, nothing I have read about matches your symptom

Fuel pressure should be 60psi average, there is no fuel pressure sensor
Not sure what this means "fuel delivery (never skipped a beat)" unless fuel pressure gauge was attached and visible to driver when loss of power occurred
On the fuel pump assembly in the gas tank are the fuel pump, of course, lol, and the Fuel Pressure Regulator(FPR), either could cause a momentary loss of pressure, so loss of power
I assume fuel filter has been changed just to take that off the table, and should be done every 5 years in any case

If you can watch Live Data watch the Knock Sensor data, see if it spikes when power loss occurs , indicating Lean mix, or failing Knock sensor

Computer issue maybe, but I would expect other signs and some "odd" codes when a computer starts to fail
If you have a code reader you could do a "sanity" test by unplugging one sensor at a time and see if computer sets correct code when engine is started