Hard Acceleration Backfire

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Dec 26, 2009 | 08:47 PM

12secLX

Thread Starter

Junior User

Joined: Mar 2003

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Hard Acceleration Backfire

I have an 04 SCREW with the 5.4. If I drill it off the line it will turn the tires and run out well. If I kick it at 50 mph it will backfire and pop under hard acceleration. If I let off of it the motor will start to come back into it and I can ease my way into it again to take off.

I also have the cam phaser tick and the truck has about 90k on it now.

I am leaning towards plugs but does anyone else have an idea what it might be?

Also if you know a good dealership in Indiana, Kentucky, or Ohio that will stand behind a plug change please let me know.

Thanks,

Rod

Dec 27, 2009 | 10:42 AM

iilijah

Junior User

Joined: Dec 2009

Posts: 83

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some are having problem with the cats. you should look at that.

Dec 27, 2009 | 12:02 PM

bridge

Sick 'n Tired

Joined: May 2006

Posts: 2,969

Likes: 47

From: League City, TX

I'm still having this same problem with my wife's Expy 5.4L. It's fine unless you get on it and it starts making a loud popping/misfire sound. Initially it was misfiring and throwing white smoke and was throwing codes. Dealer said it was one of the cats and replaced it under warranty and did a fuel system flush in case it was stuck injectors. After I picked it up it was still doing it so they replaced the other cat and replaced 2 plugs and 2 COPs. They said I need all new plugs. Again, picked it up and it's still doing it, so I changed the other 6 plugs myself. Still doing it. I'm thinking of replacing all the injectors and the other 6 COPs and see if that finally does the trick. However, it's not throwing any codes (it did initially, CAT insufficiency codes and misfire). I'm taking it back to the dealer this week and see what they'll do. The injectors and COPs are covered under my extended warranty.

Jan 10, 2010 | 10:29 PM

12secLX

Thread Starter

Junior User

Joined: Mar 2003

Posts: 58

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Well I changed all 8 plugs and went back with Motorcrafts. I know some of you out there are thinking, "Why motorcraft?" I have raced motors most of my life and found Motorcraft makes a quality part. Just look at the oil filters on a 300 straight six. If you owned one you know the rattle on start up with any other filter.

Well my problem was fixed by changing all 8 plugs. It has been a week of daily doses of open throttle at all temps and speeds and the truck is running like new. If any thing develops I will be sure to keep you up to date.

Rod

Jan 11, 2010 | 09:36 PM

GwarForAll1021

Elder User

Joined: Jun 2008

Posts: 574

Likes: 1

mine does that when i have my edge plugged in

its your truck over reving till it hits the shift point and the trucks limiter kicks in.

after it makes a quick bounce off the limiter it kicks into the next gear and delivers a nice POP! to make you know **** YEA IM IN GEAR!

it was kinda cool at first but soon figured out its not good. i took the tuner out of the truck.

you didnt say you have a tuner. im sure you dont. if your trucks shifting out of 1st at 50 your truck is defiantly not shifting on time. mine always backfired at over 5000 RMP

just my .02