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: Issue involving spongy brakes after multiple bleeds.

You may have rear brakes out of adjustment. I'd try to adjust them until you get a light drag on the drums. Check both front calipers to make sure the slides are free and lubed well. Then you should have...

Q: I just got my serpentine belt replaced and it's squealing when I start the car and sometimes when I hit the gas

Noise of that type is due to a failed or failing bearing in one of the pulleys or accessories (e.g., alternator, water pump, A/C compressor) that is driven by the serpentine belt, the belt is not properly tensioned, or the...

Q: Q: Iac valve

Danny. We appreciate you contacting us and asking questions - but this issue with your Dakota is something that we really can't "guess" at what might be normal or is wrong with your Dakota. Any responsible mechanic would insist on...

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...
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...
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.