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team_r5 · 07-24-2018, 11:51 AM

Quote:

Originally Posted by Arch Hoagland

I did a Google search...seems that the coil over plug and plug wires were the issue, some due to getting wet and others due to heat.

Was it raining during or prior to the problem?

It wasn't. In fact it hadn't rained on us in about a month at that point.

Soppy · 07-24-2018, 05:47 PM

Had a similar problem with my car . Would get a code for a misfire on certain cylinders. Drove around with the scanner connected and could actually see the misfire on the live data. Moved the coil from the affected cylinders to a good one and problem followed . Replaced the coils giving the misfire and no more problems. Justbe sure you know how the cylinders are numbered to get the rite coil.

team_r5 · 07-30-2018, 11:05 AM

Quote:

Originally Posted by Soppy

Had a similar problem with my car . Would get a code for a misfire on certain cylinders. Drove around with the scanner connected and could actually see the misfire on the live data. Moved the coil from the affected cylinders to a good one and problem followed . Replaced the coils giving the misfire and no more problems. Justbe sure you know how the cylinders are numbered to get the rite coil.

Interesting. Well, the mechs still have it and are still stumped after 1.5 weeks. They were finally able to reproduce the problem, but can't figure out the cause. I would guess that what you're talking about would be something they'd do relatively early in the troubleshooting process.

On the other hand, I'm having a difficult time getting more than very basic information out of them, so who knows what they're doing. Frustrating.

Mudsock · 07-30-2018, 12:09 PM

You could have marginal plug wires from a bad batch of wire. But why only half and evenly numbered? Plug wires are relatively inexpensive. If you actually need them, an OEM set will generally last longer. You could go to an auto store and buy some wire and terminations and replace just one or two wires to see if that cures a cylinder. Examining the plugs could give a clue. If you have worn valve guides (not likely, but possible) the plugs could be fouled enough to misfire. A stray bottle, or a garden hose sprayer, could be used to wet down the ignition wires and generate codes at idle.

Sometimes the dealer doesn’t find a problem. One of the secretaries in the engineering department at Delco had a car with a misfire. The dealer couldn’t find the problem after multiple tries. The ignition guys in the department took a look and fixed it in short order. It was a single bad ignition wire.

Logic, knowledge and persistence will result in a solution.

twinboat · 07-30-2018, 12:12 PM

No plug wires on the Ford V10

emcee · 07-30-2018, 12:19 PM

Maybe a tank of bad gas?

team_r5 · 07-30-2018, 03:02 PM

All that is possible, though unlikely with the gas as there was a refueling in there. I'm still stuck on the fact that I feel nothing at all when it's supposedly misfiring, and it does it randomly, or seemingly so.

When they finally reproduced it, they reported back that it "runs great... we're not even sure it's misfiring!" Well yes, that's what I said multiple times when turning it in. Seems like more of a sensing problem or interpretation-of-data problem to me. But I'm far from an expert -- maybe with a V10 you won't feel/hear a misfire, even if it goes on for a few minutes.

TeJay · 08-01-2018, 06:50 AM

team r5,

Why are you stumped because you can't feel an intermittent miss that may be one miss out of say 50 at 2,000 RPM's? It's amazing that an intermittent miss can be discovered at all and even pin pointed as to the cylinder. If the codes are saying it's missing believe it.

The dealer techs have always been hampered by dealer policies and diagnostic time. I remember very well early on in the 80's when the industry went to OBDI and all vehicles went to computers.

All the talk was to get rid of the parts changers and teach the techs to think and diagnose before replacing parts. The problem was the dealers were very reluctant to charge/pay for diagnostic time. We have no problem paying a doctor for an office visit and all the tests so they can diagnose what ails us but we can't charge for tests when we have our vehicle diagnosed.

Then there's the computers. Many, many an owner believes that a scan tool tells the tech exactly which part to replace. That is far from the truth. A SCAN tool is no different than taking your PULSE, BP, TEMP, EKG, CT-SCAN or an MRI. They are all tools to look at to compare with what should be normal. We all understand that.

I've been told by several Service Managers who can't find young kids who can THINK. They know the electronic tool very well and have no trouble hooking them up. The tools give them symptoms which directs them down a path but they don't know how things work and they can't think beyond the symptoms. They just don't have basic understandings of how things work.

Here's an example that I was given. A vehicle came in with dim headlights. The SM told this young kid to check it out. The kid came back and said he couldn't find anything except it had power to the headlights. Dah!!!! If the lights are on but dim sure it has power. It had a bad ground so power was not getting back to the battery but the kid didn't understand how things worked so he couldn't think beyond.

I got dozens of those stories. Follow the symptoms.

team_r5 · 08-01-2018, 08:25 AM

Well no, I'm stumped because I'm stumped, as are (were?) the mechanics. And it took them about a week to even re-create the condition.

When it would throw the code (and the flashing check engine), it would do it for anywhere from 5 seconds to about 3 minutes at a time, and on 4 different cylinders, so almost certainly more than just one miss at a time. I just figured, from my admittedly limited experience with misfires, that it would be something I'd feel, particularly if it's ongoing for a few minutes. But again, maybe I wouldn't. It's my first V10.

At any rate, latest update is they claim to have it fixed now. Serpentine belt tensioner. Not clearly seeing the connection, I asked for an explanation of how that would cause the misfires and basically got a long winded "trust me, it would" so I'm crossing fingers this is it.

Randalpho · 08-01-2018, 10:34 AM

A weak belt tensioner can allow the belt to deflect/bounce which in turn effect the crankshaft speed (slow down/speed up). This makes the PCM think that there is a misfire when there is not.

PbdBlue · 08-01-2018, 10:39 AM

Quote:

Originally Posted by Randalpho

A weak belt tensioner can allow the belt to deflect/bounce which in turn effect the crankshaft speed (slow down/speed up). This makes the PCM think that there is a misfire when there is not.

Or one that has a bad bearing and binds up intermittently. As mentioned misfires are detected as rapid rpm variations by the crank position sensor.

spyderRV · 08-01-2018, 11:15 AM

Fan belt?

team_r5 · 08-01-2018, 04:33 PM

Ah-ha, that makes sense. Thanks! Very much hoping this is it.

THenne1713 · 08-01-2018, 11:37 PM

COPS (Coil On Plug); I would start w/ replacing COPS if nothing else, and see if problem reoccurs? Maybe computer inspection of circuit board/ wiring for varmints/ insects? Flashing light in my OM for the 99 says Flashing SES= PULL OVER; Steady Light= Safe to Drive.
(Something does not make sense?)