Misfire on cylinder seven again

JASONPYZO

MEMBER
2004 DODGE DAKOTA
4.7L
V8
2WD
AUTOMATIC
96,000 MILES

Hi, the check engine light came on and I have had a misfire on cylinder 7 again, this has happened a few times. I cleared the code then this time I swapped cylinder 7 coil to cylinder 1 and drove for a few days until the engine light came on and it was cylinder 7 again. So I cleared the code once again then I swapped cylinder 7 spark plug to cylinder 1 and drove again. It happened again to the cylinder 7. So I parked it this time because I've heard it might be a collapsed lifter. Could that be the case or do you have any other suggestions?

2 Replies

JACOBANDNICKOLAS

MECHANIC
108,179 POSTS

I'm questioning if it is a fuel injector issue. Also, you mentioned that you switched the spark plug and coil which didn't move the misfire (good idea by the way). So, I feel it is likely fuel related. Here is a guide to help you step by step with instructions in the diagrams below to show you how on your car.

https://www.2carpros.com/articles/how-to-replace-a-fuel-injector

By design, these engines usually hold up well, so unless the engine hasn't been serviced properly, I wouldn't suspect a lifter to be collapsed. Also, if there was one collapsed, you would hear it ticking.

Another thing you can check is fuel pressure leak down to see if it drops fast. That could indicate an injector leaking.

Here are directions for performing a leak down test:

2004 Dodge or Ram Truck Dakota 2WD V8-4.7L VIN N
Fuel Pressure Leak Down Test
Vehicle Powertrain Management Fuel Delivery and Air Induction Fuel Pump Fuel Pressure Testing and Inspection Component Tests and General Diagnostics Fuel Pressure Leak Down Test
FUEL PRESSURE LEAK DOWN TEST
Test 1 - 2

Another idea would be to switch two of the fuel injectors. Here are directions for removal and replacement. Try that also.

INSTALLATION

Warning: the fuel system is under a constant pressure even with engine turned off. Before servicing fuel injector(s), fuel system pressure must be released.

To release fuel pressure, refer to Fuel System Pressure Release Procedure.

To remove one or more fuel injectors, fuel rail assembly must be removed from engine.
1. Apply a small amount of clean engine oil to each fuel injector O-ring. This will help in fuel rail installation.
2. Install inject or(s) and injector clip(s) to fuel rail.
3. Install fuel rail assembly.
4. Install air cleaner.
5. Start engine and check for leaks.

Check out the diagrams (Below). Please let us know what you find.

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