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I have a 2013 5.0 which has developed a stumble and loss of power on acceleration. Under light to moderate acceleration it sounds like an old 4 barrel carburetor has opened the secondaries, then starves for fuel. This lasts anywhere from 3 seconds to a minute or more. Sometimes it will clear out when floored, but not always. Occasionally I get a lot of lifter/valve noise, like it is dieseling, when this happens, but not always. It is not throwing any codes during all of this. I have replaced the spark plugs, replaced the air filter, cleaned the Mass Airflow Sensor, cleaned the intake tube end to end, and inspected it for any visible holes, cleaned the throttle body, and unhooked the battery to clear any possible hidden codes.
Throttle calibration can substantially improve throttle responsiveness over "factory standard." Many people notice what appears to be sluggish throttle response or a "dead area" at initial accelerator depression. Throttle calibration can take care of these.
1) turn the key in the ON position (don't start the engine)
2) press the gas pedal down slowly all the way down
3) let go of the gas pedal fast so it come back up
4) turn key into the OFF position
repeat steps 1-4 two more times then start engine.
Most drivers notice an immediate change in throttle response, but depending on your driving style, you may need to repeat this procedure periodically due to the computer's adaptive programming. You likely need to repeat this procedure any time the battery is disconnected.
I Tried this, and there was no change to my issue, but I did get better throttle response!! Thank you!!
I went by my friendly O'Reilly's and had them hook up the scanner, still no codes. They ran live data to see what was going on. I am attaching a pic of the page that is baffling me and the parts guy. The highlighted line reads FUEL SYS 1 as closed, which it should be open by the time the engine warms up. this tells me something is wrong somewhere..... but where?????
The highlighted line reads FUEL SYS 1 as closed, which it should be open by the time the engine warms up. this tells me something is wrong somewhere..... but where?????
That's telling you if your ECU is operating in open or closed loop mode. As you said that picture was taken when it was in closed loop mode. Once the engine warms up it spends most of its time in closed loop, where it uses feedback from the O2 sensors to trim the fuel and reach an optimal air/fuel mixture. If the engine is warm and operating properly, there are very few times it goes into open loop mode (WOT, highway coasting, overheat conditions...). If you were just sitting there idling warm when the picture was taken there is no issue with your ECU being in closed loop mode.
Did you find the problem? My 2011 is doing the same thing and has been at the dealership for 4 days so far. I've replaced everything you mentioned above as well. Thanks for any guidance you can give.
Did you find the problem? My 2011 is doing the same thing and has been at the dealership for 4 days so far. I've replaced everything you mentioned above as well. Thanks for any guidance you can give.
Yes, can position sensors. Changed them out and it went away.
11-27-2018, 10:43 PM
2013 5.0 stumble and loss of acceleration
