2004 Ford F-150 5.4 Irratic Idle- HELP


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2004 Ford F-150 5.4 Irratic Idle- HELP

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Auto Repair Home>> Automotive Repair>> Engine Troubleshooting

Bdoom2
User

Aug 15, 2020, 4:25 PM

Post #1 of 4 (768 views)

2004 Ford F-150 5.4 Irratic Idle- HELP	Sign In

Hello!
I know, I bought a Ford with the worst engine in automobile history. Double whammy. The idle is very irratic - ranging from 500 to 800 rpm and misfiring to no end. I have replaced all 8 spark plugs, but that was 2 weeks ago. CEL came on yesterday with a P0355. Ok, I replaced Ignition Coil on C5. CEL hasn’t come back on yet. Have replaced the TPS and cleaned the Throttle Body, and it still idles badly and misfires. Video linked was taken before replacing the junkyard TPS with one from auto parts store.

This engine makes me want to tear my brains out!

It also has an issue where it won’t crank sometimes and the anti-theft light blinks rapidly. I read online in multiple places to get a new key programmed. Tried that and the problem still persists.

https://youtu.be/brC47Iu9Kls

Hammer Time
Ultimate Carjunky / Moderator
Hammer Time profile image

Aug 15, 2020, 5:02 PM

Post #2 of 4 (751 views)

Re: 2004 Ford F-150 5.4 Irratic Idle- HELP	Sign In

No, you didn't buy the worst engine in history. That's actually a pretty good engine although it does have it's issues.

They have a lot of valve train issues so I would advise a complete compression test before going any further.

You may have to study sensor data to get a feel of what is going on.

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We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

Bdoom2
User

Aug 15, 2020, 7:32 PM

Post #3 of 4 (738 views)

Re: 2004 Ford F-150 5.4 Irratic Idle- HELP	Sign In

I will check the compression soon. Here is another video with the livestream data from my scan tool:
https://youtu.be/3xWFzvmBk7M

Bdoom2
User

Aug 15, 2020, 7:37 PM

Post #4 of 4 (734 views)

Re: 2004 Ford F-150 5.4 Irratic Idle- HELP	Sign In

The truck is also shaking like a mad fiend at idle.

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