2000 Excursion 6.8L v10. 207,000 miles


I recently took the heads off to work on the exhaust manifold. Prior to this, the truck ran great with no issues other than a couple of the coils being on their last leg. I got the truck back together and discovered a hesitation. The code showed a misfire in cylinder 10. I decided to replace all the coils with some cheap knock off replacements since I didn't want to spend a lot of $ on something that I wasn't completely sure was bad or not. After replacing the coils, I took the truck on a 15-20 mile trip and everything seemed normal. About a week later I took the family on an 80 mile trip and I thought I felt a little hesitation, but wasn't sure if it was do to the bumpy icy roads. Overall it ran great. On the way back from this trip, I felt a definite hesitation. I was now showing a cylinder 8 misfire. This progressed to a cylinder 3 and cylinder 6 misfire. On my torque app, the error 8 & 3 code went from the light brown color to the red color.


My question are as follows:


Do these misfire codes only show for a misfire, or can than be for other issues like with other brands? Am I correct in assuming that even if there was low compression or a Mass air sensor or fuel pressure issue as long as the plug is sparking it wont throw a code?


Is it reasonable to assume that since my cheap coils seemingly ran great for 100 miles before the problem resurfaced that it is likely the new coils are crap?


If this is only a camshaft or crankshaft position sensor issue, then it wouldn't throw a misfire code, right? So its not likely these are a concern.

 

Replace the cheap replacements with Ford OEM COP's and I bet your problem will be solved. (I hope you kept your old ones as spares).

There is no aftermarket coil that is as good as OEM, with the exception of Weapon X, if the information from a few years ago still stands true.

It's too bad you didn't post here first, before you replaced all the coils. We could have saved you a ton of money and helped you ascertain what exactly was causing the miss. It might very well have only been the coil boot that needed replacing.

Stewart

 

Any opinion on the Denso 673-6000 COPs?
Is Denso the Ford OEM supplier or maybe at least as good as a Motorcraft?

 

I did make a post right after I ordered the new coils. I only paid $50 for the set of 10 and for me it was worth the $ to see if the misfire in cylinder 10 went away, which it did. This and the fact that the original 16 year old, 270000 mile coils were old and, even according to the Ford service dept, were going out. What tests they performed to determine this, I don't know. I kept all the old ones, so I will swap out the three that are giving me issues.

 

Denso and Motorcraft are the same thing... identical. I'm running 10 new Denso COPs... made a nice difference in my Ex.

 

Did you check spark plugs? Just curious.

 

Plugs are brand new, motorcraft. Properly gapped. I am 99% certain is the coils. I will be putting on old ones to replace the ones I know are throwing codes. If that resolves the issue, I will start replacing the coils with higher quality ones.

 

Might want to use the newer coil boots on the old OEM COPs, if they fit. Old coil boots have been known to cause misfires when the coils are good, even when the boots pass a visible inspection.

Stewart

 

Same here, the Denso COPs have the Motorcraft part numbers under the Denso sticker on top, about $23 from Rockauto.

 

I put the old coils back on the 3 cylinders that were misfiring, but I left the new boots on. I cleared the old codes as soon as I turned the truck on. After about 5 miles, when the truck was warmed up, the same 3 codes popped up again. I know these old coils aren't the best, but what are the odds this would happen? I highly doubt its the plugs. Ive never had a bad one before, let alone 3 at one time. Any other thoughts or suggestions? When I get a chance, Im going to pull the plugs and inspect them and make sure there is no moisture, but I really don't think this is the issue. Do the Ford codes for misfire represent anything else? like a injector issue?

 

A misfire code just means the cylinder did not fire.
The spark plug may be cracked, the boot may have arced thru, the spring is so rusty the pulse did not get thru, the coil is shorted internally, the coil ground signal thru the PCM did not complete, the fuel injector is clogged or stuck, the injector ground signal thru the PCM did not complete, the connectors are not attached completely, the power is not getting to the coil or injector.

 

I think it's time to inspect the wiring to the COP plugs on the engine wiring harness, some folks have had the wires separate at the plugs, or loose fitting plugs where the tabs are broken or fatigued.

 

So there aren't separate codes for injector issues then? What kind of short sided engineer wouldn't do that. Lazy *******s.

 

What about making sure that the coils/boots are securely seated on the plugs???

 

Check to ensure your injector clips did not break when installing your COPs. They are brittle and break easily when disassembled. I just did all 10 plugs and a few coils. It fixed my original misfire issue, but I had another cylinder misfire show up. Turns out, I accidentally broke numerous injector clips and didn't even notice. A zip tie fits through nicely to fix you right up.