Skip the auto shop - Our mechanics make house calls

Q: Sluggish when starting from braking position and when going uphill

asked by on

Truck will work relatively normal when cold, as soon as engine heats up acceleration gets sluggish and very busy especially when going uphill. Been told about it being in "limp in"mode and something to do with transmission maintenance. Would like more specific model/year details to go fix. There is also a loud roaring sound when accelerating and it gets quite hesitant when switching to Reverse (R). Thank you.

My car has 114000 miles.
My car has an automatic transmission.

A: Hey there. If your truck is in limp in mode...

Hey there. If your truck is in limp in mode, the PCM (powertrain control module) believes there is something wrong and it is attempting to protect itself. The place to start is connecting a scanner to your truck to read any codes and study the scan data. Only with this information can we point you in the correct direction. By following a diagnostic process that begins with a scanner, we can discover clues as to what is wrong.

As for the roaring sound when accelerating, this is most likely your fan clutch locking up. When the hydraulic fan clutch locks up, the fan will pull lots of air through the radiator and create a very loud rushing noise. This is normal, with one exception. If the fan clutch is frozen, it will be permanently locked up and this will creating a non-stop rushing noise heard at all times. If the noise goes away once you reach speed, then it is working correctly. If the noise is always there (cold and warm), then you should have the fan clutch replaced. A qualified professional from YourMechanic can come to your car's location to diagnose the vehicle's loss of power if you are still having trouble.

Good luck!

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!

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Save up to 30%

Get a quote

What others are asking

Q: 1.69 amp parasitic draw, previous owner had hitch. Everything stock

The best way to find the draw is to pull fuses out one at a time. This isolates which circuit needs to be diagnosed. You may have a module (computer) that is not going to sleep. I found a technical...

Q: Is the 2002 Lexus is300 with manual transmission a good car and why?

This is a relative question depending on your zip code and supply and demand for cars of that type in that area. Kelly Blue Book complies comparative sales of specific cars of a given type with specific options and compares...

Q: I hear the fuel pump coming on but sometimes it won't start

Just because you hear the fuel pump run does not mean it is pumping the correct pressure to the injection system. If the pressure is real low or the filter is plugged solid, then the pump may not get enough...

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 P0052 code means This code is seen when the Engine Control Module (ECM) tries to control the...
How Much Does a Mechanic Make in Vermont?
Automotive technician jobs in Vermont have an average mechanic salary of $37k, with some mechanics earning a salary of $53k.