Skip the auto shop - Our mechanics make house calls

Q: Truck won't accelerate past 35mph

asked by on

Suddenly for no reason my truck won't accelerate over 35mph it's a 4wd 4spd tranny with a 350. She accelerates through 1st 2nd and 3rd without any issue up to 35. When I shift to 4th she just stays at 35 no matter how much gas I give. How do I fix this issue?

Hi There, This may be a sign of a clogged catalytic converter. The catalytic converter converts toxic exhaust gases into less harmful pollutants that are suitable to be expelled into the atmosphere. When this is clogged, this causes these gases to be backed up into the exhaust system not allowing the engine to breathe properly. When this happens, the engine is forced to work much harder to expel these gases. This often results in the engine bogging down, hesitating, shaking and causing very poor fuel economy. This should also cause a check engine light to come on as the O2 sensors should be reading the incorrect amounts of oxygen in the exhaust gases if this is your problem. I would recommend having an expert from YourMechanic come to your location to diagnose and replace your catalytic converter.

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: Put my GMC into gear and when I give it gas it just wines and won't move.

Hi there. Check the clutch to see if it is slipping. When a clutch slips, the engine will continue to operate but the transmission will not drive under a load. If the clutch is new and the noise is still...

Q: 2002 GMC Envoy message displayed on message board, turn engine off now. What does this mean?

Hi there. The message could have came on for something that may have been active on the engine or transmission. If the light comes on again, then the computer (ECM) should store the events and you could have them read...

Q: Ac condensation leaks a lot of water from drainage tube outside under yukon 2005, even if I haven't driven it in a day, is this ok

You will see varying amounts of condensation draining from the a/c drain depending how much humidity is in the truck. This is normal. The larger amount you see if just an indication of how much humid air is being removed...

Related articles

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...
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.
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.