Skip the auto shop - Our mechanics make house calls

Q: Engine takes to long to warm up I've replaced thermostat already and it misses horrible till it warms up its a 4.9 engine

asked by on

Truck starts up in the morning and idles tight up then dies and misses and runs rough then warms up and runs good until i stop for a few minutes start it back up and it misses again until it runs for a few minutes

My car has 173000 miles.
My car has an automatic transmission.

These engines are known to get real bad carbon build up on the back sides of the valves. If you engine has a hard time getting to operating temperature then it will also cause the engine to carbon up even faster. Once you correct the engine not getting up to operating temperature by replacing the fan clutch if it is locked up. You will then need to remove the excessive carbon from the intake system ans valves using Ford combustion chamber cleaner or equal and allow the engine to suck it in to the intake when the engine is cold so the carbon will soak up the cleaner. Shut down engine and let sit for about 20 minutes and repeat process. Once this is done then start and run engine at 1500 rpm for 10 minutes to loosen any remaining carbon deposits. Once this is done then you may have to replace spark plugs and also should have the fuel injection system cleaned. The injectors get carbon deposits on them that cause the spray pattern to be incorrect and cause running issues. Have a mechanic like one from YourMechanic come to you to perform all these services and repairs.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  • Home
  • Questions
  • Engine takes to long to warm up I've replaced thermostat already and it misses horrible till it warms up its a 4.9 engine

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: codes p0101 and p0303 simultaneously

The code P0101 is for a problem with the MAF sensor and code P0303 is for a cylinder number 3 misfire. The first thing to check is to make sure there is no vacuum leaks or leaks between the MAF...

Q: 2002 Jeep Liberty Limited 3.7 misfire bent spark plug tip with rough idle

I can't find any information suggesting there is a recall for your vehicle. Either way, you need to figure out what has failed in cylinder number two. Replacing all the injectors is not going to fix the problem in cylinder...

Q: How do I use hill start assist?

Your truck is equipped with Hill Start Assist. Hill Start Assist keeps your vehicle from moving when stopped on a hill. To use Hill Start Assist. Keep the brake pedal pressed to activate Hill Start Assist. Hill Start Assist...

Related articles

How Long Does a Heater Control Valve Last?
Keeping the right amount of coolant in a car is essential in keeping the engine at the right temperature. Failing to have the right amount of coolant or even bad elements...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
P2428 OBD-II Trouble Code: Exhaust Gas Temperature Too High Bank 1
P2428 code definition A P2428 trouble code signifies that the PCM has detected a problem in the exhaust gas temperature sensor circuit in bank 1, which subsequently contains the number one...