'05 5.4 cylinder 4 issue - Ford Truck Enthusiasts Forums


'05 5.4 cylinder 4 issue

Old 10-09-2018, 02:47 AM
James Tracy
James Tracy is offline
New User
Thread Starter
Join Date: Oct 2018
Posts: 1
James Tracy is starting off with a positive reputation.
'05 5.4 cylinder 4 issue

Hello all, curious if there's anyone that have one cylinder in particular causing them grief. My '05 5.4 has 280 000km (174 000 miles) on it. The first 2/3 of that mileage was a good balance of commute/towing/sport. The last 1/3 it has been mostly short commutes and light towing. I'm on my 3rd set of plugs and coils. The previous set #4 was destroyed in less than a year. When the 3rd set was installed 7 months ago compression test showed #4 down significantly but not worrisome for what the truck does now. Under "prolonged moderate" or short hard load, #4 misfires. The plug has been pulled twice to make sure its not deteriorating. My uneducated guess is that with the compression loss in #4 it can only sustain so much pressure. Seems to be a lot better when I keep my shift points at 2500rpm or less and cruising speed at 2000rpm or less
Old 10-11-2018, 11:29 AM
Rumble phish
Rumble phish is online now
Senior User
Join Date: Aug 2018
Location: Riverbank, CA.
Posts: 106
Rumble phish is starting off with a positive reputation.
Have you put a scanner on it? Is it showing a check engine light or throwing any codes? You definitely have an issue in #4, and it doesn't sound like it's electrical. Have you tried swapping and known "good" COP onto the #4 plug and moving the COP on #4 to another cylinder to see if the misfire follows the COP from #4? The loss of compression in #4 you say is "significant". What is significant? What is #4 at compared to the other cylinders. I think this loss of compression is going to lead you to your issue.

Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service

© 2018 MH Sub I, LLC dba Internet Brands

We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.