Engine Knock after Spark Plug Change

[Jason Little]

I just changed all my spark plugs because I was getting code P0300 (may have been a number at end, I don't recall which one at the moment). The coil packs were a pain to get out and I actually broke two boots off inside, which was also a pain in getting out, but they were all removed and the broken ones replaced. So I get everything back together and start it, and I have a knocking sound. Any idea what this would be?

 

[LokiWolf]

Year, and miles are a good start....


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[JExpedition07]

5.4L 3V? Check torque on all 8 spark plugs, but particularly those back 2 cylinders stuffed into the firewall can be hard to torque. The trick is one long and one short extension and a swivel. Then you can get good torque on them. What happens is without the proper torque cylinder pressures will loosen it right up and allow blow by and excess sound. Likely just didn’t torque the back 2 as much as you think you did lol.

 

[Jason Little]

5.4L 3V? Check torque on all 8 spark plugs, but particularly those back 2 cylinders stuffed into the firewall can be hard to torque. The trick is one long and one short extension and a swivel. Then you can get good torque on them. What happens is without the proper torque cylinder pressures will loosen it right up and allow blow by and excess sound. Likely just didn’t torque the back 2 as much as you think you did lol.

Its a 2017 Expedition EL XLT with 3.5 Ecoboost. I had planned on pulling the coil pack connector plugs one by one and starting it to see if I can isolate where issue is, and then just hopefully work on that one. They are a pain to get to as you mentioned. Thanks for the feedback.

 

[JExpedition07]

Its a 2017 Expedition EL XLT with 3.5 Ecoboost. I had planned on pulling the coil pack connector plugs one by one and starting it to see if I can isolate where issue is, and then just hopefully work on that one. They are a pain to get to as you mentioned. Thanks for the feedback.

Yep same rule can go for the EcoBoost too they have those back ones shoved under the wiper cowl area also.

 

[Jason Little]

Yep same rule can go for the EcoBoost too they have those back ones shoved under the wiper cowl area also.

I pulled both back coil packs and plugs, inspected and put back in, problem went away. Thanks again for the help.