V-10 Excursion missing; no code or pending code

I chased the miss down in my old V10 for a long time. I pulled the coils, gapped and replaced the plugs.. still had a miss. Moved the coils around trying to isolate the miss with no luck.

I read on the FTE forum that I could change the boots and springs on the coils and decided that I would. I ordered new boots and springs.... pulled all the coils off and while pulling the old boots and springs off I noticed this....



Upon further inspection 6 out of the 10 coils in my 99 had similar cracks in the body of the coil.

I ended up replacing all 10 coils.

Problem with the miss... solved...

I would suggest pulling the coils and inspecting them for similar cracks.

BTW.. I bought Uneek Supply coils x10 for around $100.00. They had good reviews and really stand behind their product. They worked perfectly and were still on the truck (without a miss) when I sold the truck.

Here is a pic of these aftermarket coils...



If you ever replace the coils, whether Motocraft or aftermarket make sure that the springs inside the coils are firmly seated in the coils before installing them.

Thanks!

Jeremiah

Yep! back then the 3/4 and 1 ton trucks were in their own category when it came to emissions. now it is completely different!

Interesting, you would think it would be easier to just standardize emissions....

Mine was sold in IL. anything over 8600 lbs (I think 8601 lbs) in IL did not have to be OBD2 compliant due to the 8900lb GVWR. I think in CA though it had everything necessary for OBD2. and the X with the 5.4 had an 8600lb GVWR and those had full OBD2 compliance. lots of variables that made them have different versions of emissions!

Mine was originally sold in the Tampa area, but I don't know what it has on it. It does set pending codes that will indicate what cylinder is misfiring. It may take a bunch of misfires to set the pending code. I've been intentionally getting it to misfire to see if it will set a pending code.

Yeah, many or most V10s did not have the typical OBD2 emissions package (they are all OBD2 reader compatible though) since they are all over 8500 pounds.

Mine came with the Low Emissions Vehicle package, so it came with everything including EGR and does monitor cylinder contribution.

You guys know the V10 way better than I do, just seems logical to me that if a condition is noticeable to the driver, i.e. is creating a driveability issue, then it should be noticeable to the PCM, i.e. as evidenced by a code of some sort. I know, logic doesn't win the day in trying to figure out how vehicles are engineered....

Dodge Guy that is unusual to have OBD I software in an 02...much less no O2 sensors or EGR...any idea what market your truck was intended for? Had to be outside the US somewhere...

And like I said earlier, some excursions do not monitor misfires. It all depends on the way the PCM is programmed which is dependent on what market the Excursion is destined for. My X doesn't have downstream O2's, monitor misfires or have an EGR system. It has a GVWR of 8900lbs, which is why in IL it doesn't have these things. Other states have there own requirements for emissions. Mine runs OBD1 software in the PCM.

BurbMan wrote:

carringb wrote:
A weak coil won't set codes until it completely fails.

That makes sense that the coil won't set a code as long as the PCM detects that it is firing, but if it's weak enough to cause a noticeable driveability issue you would think that the PCM would use its other resources like the O2 sensors to detect incomplete combustion or call it a misfire even if it doesn't know which cylinder..

O2 sensors only measure the air/fuel ratio, and not how complete combustion is, at least not directly. The closest it can get is a "slow response" or "slow switching" code, but that can be triggered by other problems unrelated to the ignition system. In reality, a single misfire will just result in more oxygen present in the exhaust (since it isn't combining with fuel), so it simply adds more fuel to the entire bank.

What the PCM is really looking for is a change in crankshaft velocity. The reason the V10 can't pick up misfires as easy is because there's more cylinders firing per revolution, so the change in crankshaft speed isn't as apparent as smaller V-motors. Its basically less sensitive to a misfire.

carringb wrote:
A weak coil won't set codes until it completely fails.

That makes sense that the coil won't set a code as long as the PCM detects that it is firing, but if it's weak enough to cause a noticeable driveability issue you would think that the PCM would use its other resources like the O2 sensors to detect incomplete combustion or call it a misfire even if it doesn't know which cylinder..