Q: Q: Truck is back-firing.

asked by on

After changing the harmonic balancer my truck was running rough. I asked the friend that did the work what he suggested, he said a tune-up. He then performed a tune-up on the truck and now it is back-firing. He doesn't know why. I asked if he adjusted the timing (thought this was done after a tune up, not sure) he said he didn't touch the timing. Please help.
My car has an automatic transmission.

There are a few possible causes for an engine to backfire. Some of the more common causes are a vacuum leak, lean condition caused by a weak fuel pump, an exhaust manifold leak, or a faulty ignition system. With the information that you’ve provided, in that the engine was running rough before doing the tune up, I would focus on either the ignition system, or the fuel system. With the backfiring showing up after the tune up, I would suspect that there has been a pair of wires crossed when they were reinstalled after replacing the plugs. This is a very common occurrence, and even the best in the business do it from time to time. With the engine running rough before the tune up, I would look more at the ignition coil, the wires, and check the fuel pressure. If you feel you could use some help identifying and/or repairing the problem, contact a certified mechanic, like those available at YourMechanic.com.

Was this answer helpful?
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
  1. Home
  2. Questions
  3. Q: Truck is back-firing.

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: My husbands gas guage has been messing up?

Hello, thank you for writing in. The fuel pump is part of a unit called the fuel module. The module also houses a float that raises and lowers with the level of the fuel. That movement is then translated into...

Q: Car won't start and is also leaking oil.

Your battery needs replaced in the car. This is why nothing will work as the key is turned to the 'ON' position. Then, if your engine does not have a valve cover gasket, be sure to install one to prevent...

Q: Q: Crank no start

Hi there. The issue seems to have a misfire with the spark plugs and wires. The smoke that is coming out of the breather on the intake or valve covers is caused by the fuel burning on the exhaust stroke....

Related articles

How Long Does a Distributor O Ring Last?
The distributor is part of the ignition system in your vehicle and its purpose is to route high voltage from the ignition coil to the spark plug. The spark plug then...
P0240 OBD-II Trouble Code: Turbocharger Boost Sensor B Circuit Range/Performance
P0240 code definition Turbocharger Boost Sensor B Circuit Range/Performance What the P0240 code means P0240 is an OBD-II generic code triggered when the Engine Control Module (ECM) detects the intake boost...
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...