Skip the auto shop - Our mechanics make house calls

Q: Nonstop backfiring

asked by on

I am replacing a few parts on my truck. DPFE sensor, camshaft position sensor and fan shroud. Since I have to replace the cam sensor I put a socket on the crank shaft and wanted to see if it would move and it did. But I couldn't get to the bolt that holds down the camshaft position sensor because it's behind the engine so I decided to leave it for now. I installed the new DPFE sensor hooked everything back up and went to start the vehicle. It is now backfiring nonstop and even blew the hoses off themes DPFE sensor. So I put the old one back on and it is still backfiring. Did I throw the truck off timing by moving the crankshaft? What could be causing it to backfire this way.

My car has 160000 miles.
My car has a manual transmission.

Backfiring occurs when the air fuel charge in a cylinder(s) fires at the wrong moment often when the exhaust valve is opening. There are backfires into the intake manifold, too, however. If during your work on the engine you moved the distributor, yes, you could have altered the engine timing. However, merely turning the crankshaft, using the harmonic balancer bolt only, clockwise is harmless. The possibility of the ignition timing being off is easy to check with a timing light...just check the basic ignition timing at idle and check the advance function, too.

It is possible that the distributor cap is cracked and/or the plug wires have carbon tracking. In working on the engine, you may have sort of "tipped the balance" on already old, failing parts and set the stage for this backfiring you are getting. Backfiring is also possible is the fuel to air ratio is too high (rich); that means there is too much fuel to create an explosive, fast-burning flame. When too much fuel, the fuel burns slower, and isn’t complete before the exhaust part of the engine cycle. When the exhaust valve opens on the affected cylinder(s), the extra air allows the unburned fuel to explosively burn and the popping noise of a backfire is heard. Check for a dirty air filter by the way which can cause too little airflow. A certified Mechanic can be dispatched to determine the causes of the backfiring in your engine.

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

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: Restricted Performance message on dashboard

When the controller sees a misfire, it shuts the fuel off to the offending cylinder, hence your "restricted performance" message. Your friend may be right because coil failures are quite common on the Jaguars. P0357 says your failure is on...

Q: Car won't start on a hot day

Hello there, many different faults can cause your 1994 Honda Accord to not start when hot. The most common would be the fuel pump, spark plugs, cap + rotor, coil, fuel filter, starter, battery cable, or a wiring harness fault....

Q: Shifts into reverse but locks up.

Hello. Thanks for writing in about your Ford Ranger. From what you've described, your transmission has either a broken gear or the shift forks have broke causing it to get stuck in a forward gear. You will need to have...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
What Causes Hoses to Leak?
While the largest part of your engine is mechanical, hydraulics plays a significant role. You’ll find fluids at work in a number of different areas. Your car's fluids include: Engine oil Transmission...
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...