Code P0303, misfire?

DJMEATMAN

MEMBER
2010 JEEP WRANGLER
3.8L
V6
4WD
AUTOMATIC
275,000 MILES

Got a P0303 code, so far, I have changed the coil, plugs, plug wires. Ran fine after sat for a day started up and threw the P0303 code again. What should my next project be injector maybe?

Monday, May 22nd, 2023 AT 11:28 AM

3 Replies

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Yep, the fuel injector would be next. Can I ask if the engine is making a slight ticking sound? If so, can you please shoot a quick video with your phone so I can hear the noise? that way I can tell for sure what's going on. You can upload it here with your response. You might have a valve train problem.

Here is how to change the fuel injector out and a guide on misfire problems:

https://www.2carpros.com/articles/engine-misfires-or-runs-rough

and

https://www.2carpros.com/articles/symptoms-of-engine-misfires-a-step-by-step-guide

Check out the images (below). Let us know what happens and please upload pictures or videos of the problem so we can see what's going on.

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Monday, May 22nd, 2023 AT 5:58 PM

DJMEATMAN

MEMBER
2 POSTS

Okay, thank you. No ticking, so my next project will be injectors, should I replace all 6 while I have it apart being it has 275,000 miles and I don't know if they are the original ones?

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Tuesday, May 23rd, 2023 AT 10:10 AM

KEN L

MASTER CERTIFIED MECHANIC
48,363 POSTS

Yep, that would be the next step. Also, I have seen these engines have a lot of intake port carbon build up which can cause misfire issues. Have you done a compression test?

https://www.2carpros.com/articles/how-to-test-engine-compression

Please go over this guide and get back to us.

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