Skip the auto shop - Our mechanics make house calls

Q: Car sputters and backfires under load

asked by on

I have an 88 mustang with a new cam, springs, coil, distributer, fuel pump, spark plugs, wires, timing chain and I'm having a sputter problem if I go over 3500 rpm and if I keep pushing it it will backfire. Then when u let rpms come back down it continues to sputter till u turn car off and back on. Then it's good till u go over 3500 rpm again?

My car has 292000 miles.
My car has a manual transmission.

This sounds like one of the valves are sticking or a spring is weak or broken. You may also have a lifter that is holding the valve open after you go to 3500 rpm and will continue to hold open the valve until you shut off the engine and oil pressure gets off the lifter. You may have to check the push rods and lifters for clogged passages. If you would like to have this checked in person, an expert from YourMechanic can come to your car’s location to diagnose the sputtering issue and determine what repairs are needed.

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: Rough idle/Check Engine light/Cylinder # 2 misfre

Hello, thank you for writing in. The spark plugs may absolutely be the cause of your misfire. Even if only one cylinder is registering a misfire at this time, you should replace all of them at the same time. The...

Q: Car sputtering when I let off gas pedal

It sounds like you have a fuel-to-air ratio issue. Anything from the idle air control valve to the oxygen sensor may have a malfunction. Diagnosis would be required before changing parts. YourMechanic can send a qualified technician out to your...

Q: Interior panels peeling off on doors

This upholstery issue affected Mustangs from 2005 to 2009 and it really does make the interior look terrible and cheap. Ford keeps on saying they are not aware of this being a widespread issue but they have repaired this...

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...
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...