Limp mode why?

Tiny
KSFARMER
  • MEMBER
  • 2013 FORD F-150
  • 5.0L
  • V8
  • 4WD
  • AUTOMATIC
  • 70,000 MILES
I was driving down a dirt road in the country, turned a corner and the engine started not wanting to accelerate. At first I thought it was traction control, not that, It slowed down to an idle. I was able to keep it running and by working the gas pedal slowly got it back to the farm shop. It did set codes after running poor for about a mile. P0300, P0304, P0306. Engine miss codes. Changed the spark plugs and looked at the wires. Plugs were worn but didn't look bad. Starts and idles for a second or two then starts running poor and sometimes shuts off. Touch the throttle and you can hear the air sucking through air cleaner, filter looks new, but no engine response. While messing with it, it set a different code that I can't remember. It was a difference between mass air and O2 flow, maybe plugged exhaust. Took it off at the engine, same problems. Disconnected the battery for a couple days while working under it. When I started it it idled normal run for most of an hour just idling. Touched the gas pedal and same thing again.
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Sunday, March 31st, 2019 AT 4:24 PM

12 Replies

Tiny
SCGRANTURISMO
  • EXPERT
Hello,

This could be a problem with a dirty throttle and throttle bore. When air is being moved through the the throttle body in the volumes that are ingested by your engine a black "sludge" cakes on the walls and throttle plate. Over time this will cause interference with the signal from the Throttle Position Sensor (TPS). Without a clear signal from the TPS the Power-train Control Module (PCM) AKA, computer" will go into limp mode to keep the engine from going lean. Clean the throttle and throttle body and get back to us with what you find out. I have also included a link for you to go to down below.

https://www.2carpros.com/articles/engine-has-low-power-output

Thanks,
Alex
2CarPros
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Sunday, March 31st, 2019 AT 4:36 PM
Tiny
KEN
  • ADMIN
Here is a guide for limp mode:

https://www.2carpros.com/articles/reduced-power-limp-mode

Please let us know what you find. We are interested to see what it is.
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Monday, April 1st, 2019 AT 11:10 AM
Tiny
BMDOUBLE
  • EXPERT
Disconnect the mass airflow sensor at the air filter housing then see how it runs. These vehicles are notorious for bugs sticking to the mass airflow element.
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Monday, April 1st, 2019 AT 2:43 PM
Tiny
KSFARMER
  • MEMBER
Cleaned the throttle body and mass sensor. Running fine now but I have to fix an exhaust leak before I can test drive it further. Thanks everyone.
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Monday, April 1st, 2019 AT 7:10 PM
Tiny
KEN
  • ADMIN
Nice work, we are here to help, please use 2CarPros anytime.
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Tuesday, April 2nd, 2019 AT 11:15 AM
Tiny
BMDOUBLE
  • EXPERT
Awesome! Glad to help!
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Tuesday, April 2nd, 2019 AT 5:19 PM
Tiny
DEANC
  • MEMBER
  • 2011 FORD F-150
  • 3.7L
  • V6
  • 2WD
  • AUTOMATIC
  • 120,000 MILES
Occasionally, first thing in the morning, transmission will feel like it is in neutral and the throttle becomes non-responsive. Only lasts a few seconds. This morning, instead of falling to idle, the engine revved while transmission went to neutral. Not a lot. Maybe 2,000 rpm. Again, only lasted a few seconds.
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Tuesday, April 6th, 2021 AT 12:14 PM (Merged)
Tiny
KEN
  • ADMIN
Hello,

This happens when the throttle bore gets dirty and the PCM loses correlation with the throttle bore due to coking. Start by disconnecting your battery and follow this guide.

https://www.2carpros.com/articles/throttle-actuator-service

Also we should run the codes as well.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please let me know what happens. Cheers, Ken
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Tuesday, April 6th, 2021 AT 12:14 PM (Merged)
Tiny
DEANC
  • MEMBER
I am not getting a check engine light. The transmission is going into neutral. Will coking of the throttle body cause that?
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Tuesday, April 6th, 2021 AT 12:14 PM (Merged)
Tiny
KEN
  • ADMIN
It could, but so can low fluid. Here are diagrams on how to check the transmission fluid level. Check out the diagrams (below). Please let us know what you find.
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Tuesday, April 6th, 2021 AT 12:14 PM (Merged)
Tiny
GIB FORREST
  • MEMBER
  • 2005 FORD F-150
  • 5.4L
  • V8
  • 4WD
  • AUTOMATIC
  • 176,000 MILES
I was driving home one day and just started missing and went into limp mode cylinder 3 was the code. I have changed all the plugs and coils and it still misfires in cylinder 3 and 1 I have switched coils and plugs around and it doesn t follow it it stays on 3 and 1.
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Tuesday, April 6th, 2021 AT 12:14 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Hi,

The next thing I would check would be compression and the fuel injector for cyl 3. It may be stuck or not operating. Also, low compression will cause a misfire as well.

Here are a couple of links to help. The first explains how to check an injector.

https://www.2carpros.com/articles/how-to-test-a-fuel-inje

When checking the injector, make sure it is getting a pulse (power) to fire.

Here is a link showing how to check engine compression:

https://www.2carpros.com/articles/how-to-test-engine-compression

_______________________________

Try these things and let me know the results. Also, let me know if you have other questions.

Take care and God Bless.

Joe

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Tuesday, April 6th, 2021 AT 12:14 PM (Merged)

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