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
  • 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: upper intake valley puddles with oil, no seal leakages, misfire at #3,5,6...

A misfire can be caused by a variety of reasons such as a vacuum leak, dirty fuel injectors, a weak fuel pump (low fuel pressure), a faulty fuel pressure regulator, fouled spark plugs, bad spark plug wires, or weak ignition...

Q: When I come to an abrupt stop, the engine stumbles like it wants to stall. Any thoughts?

A low transmission fluid level from a leak is more likely to cause the transmission to slip, especially on hills. If the torque converter clutch of the electronics that control it are sticking on, this situation may cause the engine...

Q: How do I clean the instrument panel, the interior trim, and the interior?

The interior of your truck will become dirty from time to time. To ensure that the interior of your car stays in pristine condition, clean the inside regularly. To clean the instrument panel and interior trim. Use a clean,...

Related articles

What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
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...