Skip the auto shop - Our mechanics make house calls

Q: Misfire cylinders 4 and 7.

asked by on

My truck has been misfiring on cylinders 4 and 7. I've changed the plugs and coils fuel injectors are clicking and I've ran a compression test both cylinders were around 165-170. At first it was throwing a lean code on bank one as well now is throwing a rich code. Cylinder 4 and the rich code seem to be intermittent because they go from stored codes to pending codes. The lean code was the same as well. I've checked for spark checked for vacuum leaks and checked for any fuel leaks. I changed the fuel filter and my fuel pressure was good as well.

My car has 145000 miles.
My car has an automatic transmission.

A: You need to check the PCV tube that goes be...

You need to check the PCV tube that goes behind the intake and connects into the back side. The hose can get a leak in it, causing a vacuum leak on the back side. This will create lean conditions that may be worse for cylinders 4 and 7 specifically on this engine.

If the hose is good then try and have the injectors replaced or cleaned for these two cylinders. You could swap them with different cylinders to see if the problem moves along to the other cylinder, doing so will help pinpoint the issue.

If you decide to get the car looked at, consider YourMechanic, as a certified technician can come to your location and diagnose your car’s misfire. An accurate repair can then be made once the problem has been pinpointed.

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: Engine shimming problem

Hi. When the engine shims or shakes there could be multiple things causing this problem. The most common cause is the spark plugs and spark wires are bad and causing the car to misfire. A misfiring engine will cause the...

Q: Turns over but will not start and has a strong odor of gas.

Check the location of where the fuel smell is emitting from on your vehicle. If the fuel smell is coming from the fuel tank area, then the fuel pump, fuel line, fuel filter, fuel fuller neck, charcoal canister, or the...

Q: When replacing the ecu, do I have to have it programmed upon installation?

The PCM will need to be programmed if you have theft system that is factory installed. The PCM will need to be programmed to communicate with the theft module.

Related articles

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...
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...
Rules of the Road For Iowa Drivers
Driving on the roads requires knowledge of the rules, many of which are based on common sense and courtesy. However, even though you know the rules in...