Skip the auto shop - Our mechanics make house calls

Q: Truck bogs out under load

asked by on

I've replaced the plug wires, coil packs, throtle position sensor, fuel pressure sensor, fuel filter, and cleaned the mass airflow sensor, but the truck still bogs under load. I no longer have any codes due to my battery dying but the two codes I remember are p0171 and p0174. If it helps I do have short and long term fuel trim numbers at idle and at 2500 rpm... At idle STFT bank 1 =1.6% -10.2%... Bank2 = -2.3% - -3.9% LTFT Bank 1 = 2.3% - 3.1% Bank 2 = 9.4% - 10.9% and at 2500 rpm STFT Bank 1 = 14.1% - 21.1% Bank 2 = 6.2% - 9.4% and LTFT Bank 1 = 14.8% - 16.4% Bank 2 = 18.8% - 19.5% . I must also mention that my egr valve tube that attaches to the exhaust manifold has completely rusted away. Could that cause lean mixture codes? I look forward to hearing from you soon. Thanks Bruce. P.S note the STFT Bank 2 were both in the negative at idle.

My car has 150000 miles.
My car has an automatic transmission.

First, the EGR tube rusted away will cause excessive air to get into the exhaust and cause the O2 sensors to read erratic. The main reason you most likely have a mass air sensor that is not reading correctly for the altitude you are at. You should check the mass air sensor with the key on and engine off to see if the barometric sensor is reading the correct altitude. If it is reading above 10,000 ft, then replace the mass air sensor. Disconnect the battery for 10 minutes to clear fuel control then road test for problem. If you need a diagnosis, a certified technician from YourMechanic can come to your car’s location to inspect the loss of power and advise you on repair.

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・Fair and transparent pricing

Get a quote

What others are asking

Q: Hydraulic lift gate not working

The lift gate could have many problems that might cause it not to work. I would recommend taking the truck to the lift gate manufacturer or the dealership to have them look over the problem. They will have all the...

Q: Rough idling when the MAF is plugged in

If the problem is present when the MAF sensor is plugged in, this is a classic sign something may be going on with the MAF sensor. Many other things can cause a vehicle to idle poorly as well though. The...

Q: Car cuts off when sitting still and idling. What could that be that is causing it to do that

This may be related to a dirty or failing idle air control valve. The idle air control valve monitors the air intake as it is mixed with fuel prior to being injected into the engine at low speeds and at...

Related articles

Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...
What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
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...