Reboot?

[Kentucky Dread]

I am a new proud owner of a 2008 Expedition Limited as of two days ago. It was missing some so I had the code pulled which came back po358. I replaced all of the coils and plugs today and after getting everything put back together and the battery connected I took it for a test drive. Cel came back on and it was still missing. Do I have to wait for the drive cycle to complete before the computer acknowledges the new parts?

 

[Plati]

Some codes you have to clear, they will not clear themselves. If its still "missing" and running rough doesn't sound like you found the root cause and corrected. After clearing code the drive cycle can be a bit of a wait. I've had to drive a lot over a week to complete a drive cycle. If you didn't fix the problem you will get a code again quickly after you clear.

https://www.obd-codes.com/p0358

Sounds like cylinder 8. If it was me I would have focused on cylinder 8 ONLY and not replaced all coils and plugs. You can introduce new problems like that. Gotta fix misfires before they damage CATS.

 

[Kentucky Dread]

I dont have a scan tool to clear the codes, I simply disconnected the battery while changing parts out.

 

[Plati]

Can get a $20 Bluetooth scan tool. I got one but I wish I had just paid the $100 to get a better one. The $20 ones are quite limited. I think you can even pay less. Its worth having if youre going to work on a vehicle. Frenchy knows how to get one for $4.95.

Does unhooking the battery clear the codes? I know it clears the drive cycle thing, as in then you have to complete one.

https://www.smogtips.com/check-engine-light-turn-on-off.cfm

 

[Yupster Dog]

Leaving the battery unhooked while replacing parts would have cleared if that was the problem. get the code run again it could be different now (after all your hard work) and get you closer to the problem.
You said missing some, so it is not all the time right? Follow and inspect coil wires. look for chaffing bare wire and make sure the harness is where it should be.
If all good start truck and when misfire is not happening wiggle coil wires and harness all the way back to and including the wires at the Power control module to see if you can get it to miss.

 

[Trainmaster]

Do just as Yupster said. The code should have cleared, but if you still have a miss, you still have a problem. You can have another bad coil out of the box. There are plenty of them, especially if they are cheap knockoffs. Check your wires and the connectors that go to the coils. Make sure they're snapped in. The clips break off of these sometimes and they unplug easily. Did you replace the spark plug boots also? You may want to look at #8.

You may also try replacing the new #8 coil with one of the old ones which may be better than the ones you put in.

Pretty truck, by the way. My 08's white too.

 

[Matticus]

If you want a good little scan tool, I've bought a few of these to keep in all my cars:
https://www.amazon.com/gp/product/B00PJPHEBO/ref=oh_aui_search_asin_title?ie=UTF8&psc=1

Note that this particular one is android only, but you can get them for iOS also.
I paid the $5 to get the full version of the Torque app it uses, but the free version will let you do quite a bit, including clear codes. The thing I like about it the most is that it allows me to watch my trans temps without needing to install an actual gauge

 

[Kentucky Dread]

Update! When I went to check the number 8 boot the plug fell right off of it. The clip that you squeeze to release it is broken off so it wont snap into place however i pushed it firmly onto the boot and that solved that issue completely. I removed the battery cables as I replaced my front brake pads, once completed hooked the battery back up and test drove it, perfection!