Misfires and running rich?

REDD9670

MEMBER
2010 FORD F-150
5.4L
V8
4WD
AUTOMATIC
330,000 MILES

So, it has been misfiring on almost all the cylinders. So, I changed some of the plugs and coils but that didn't change much of the problem. So, then I removed the cats which kind of helped but again not very much and now my truck is running really rich and my gas mileage has gotten pretty expensive. My truck goes up to about 20-30 kmph then starts to backfire and the welding job that was done to my exhaust wasn't very good. I don't want to buy a new truck and would like to fix this one so any help would be great.

Wednesday, August 24th, 2022 AT 2:49 AM

1 Reply

KEN L

MASTER CERTIFIED MECHANIC
54,142 POSTS

This sounds like you have one or more struck fuel injectors, to see which cylinder are having a problem, remove all of the spark plugs and look for the ones that are back or washed clean, these will be the cylinders that need to injectors replaced on.

This video and guide should help:

https://youtu.be/E6oier7agkY

and

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

Please run down these guides and report back. Also, if you can upload a short video of the engine cranking over, I can tell if the compression needs to be checked.

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Wednesday, August 24th, 2022 AT 8:39 AM