warrenoliver

I have a 2007 XLT with the 5.4L engine with 132K miles. Previously, I was having classic misfire symptoms when going up long inclines in overdrive. On several occasions, I also had the CEL flash while the truck was jerking at highway speeds. I bought a cheapo OBD reader and the Torque Pro app for my android to confirm the misfires. Since I was having misfires intermittently on most of the cylinders, I decided to change the plugs along with the COPS and boots.
I used the correct Motorcraft plugs and COPS, used dielectric grease on the connectors and torqued the plugs. The truck runs much better and I do not have noticeable misfires anymore. What concerns me is that when I look at the Torque Pro app when driving, I notice there are random misfires. As an example, I went on a 3 hour mostly highway miles trip and had a total of 12 misfires scattered among 8 cylinders - none more than 3. Today, I took a 1 hour trip and the 1 hour return trip and noticed 6 or 7 misfires total for each trip. Should I be concerned about these rare misfires spread across the cylinders? What do others see when watching the Torque Pro app?

warrenoliver

Anyone? Is it common to still have occasional misfires after replacing plugs and COPS?

HarryK

I have an'04 with 184K 5.4L and runs well except for idle. Have done most maintenance..I get 2 to 3 misfires per trip

bbrad1775

How are you viewing the missfires?
Have you checked full pressure?

tcruz0004

I have a very similar question -

Background info: my engine (rebuild by a Ford dealership & now approx 45K miles) runs great, and doesn't give me any trouble at all. However, I do get a few misfires detected by Torque Pro every time I run my truck. Usually I'll already have 1 or 2 while its warming up for 60 seconds before I leave my driveway/parking lot. It can get up to 30 during a 20 minute trip but it's usually more like 15.

I never get a CEL but I can get it to continuously misfire about 2X per second in park with the throttle at 2,000 RPMs. Other times it will misfire, usually at low RPMs, but almost never when on level ground and consistent speed.. Cylinder 7 is particularly the bad one. I plan on switching the COP to determine if I need new COPs.

Has anyone experienced anything similar, or any points to add? Am I risking anything by running the engine while its misfiring even if I'm not getting any codes?

warrenoliver

Before I changed out all of the COPS and plugs and replaced them with Motorcraft parts, I was having a lot of misfires just like you are having. Once all were replaced, my misfires drastically decreased so now I have only 1 or 2 each time I drive. I think it is probably normal and I am not going to worry about it.
The COPS are expensive but if you check out Ebay and Amazon, you can save a lot.

tcruz0004

Thanks for a reply! I was absolutely planning on using Motorcraft parts for sure. RockAuto.com had some pretty good prices too, but glad to know your problems were fixed with the COPs and Plugs. My plugs are all covered under warranty but I would have to pay $100 for a diagnosis fee.