I was under the assumption that a coil failure will result in a misfire on one cylinder and trigger the code and CEL light.

I know when my plugs were on their last leg (~93,000) I had a misfire code thrown. I went to pass a slow car and put the pedal to the carpet. It downshifted and then started missing very badly, to the point of shaking the whole truck. The check engine light started flashing but once I lifted the problem went away. New plugs resolved the issue.

I think that a plug/coil issue would either trigger a misfire code or be picked up by the O2 sensor and throw a rich on bank x code. Both of these items would cause unburned fuel to be dumped into the exhaust and throw a code and CEL as they are emissions issues.

 

any updates???

 

Mine has never thrown a code, and it is not exactly a miss. It's surging. If I floorbord it, it will jump in rpms to say 3000, pulling, then nosedive to 2500, back to 3000 hard, then nosedive. It does this as long as you stay in it. Let off, and it's perfect. It's almost like a governor. I ordered the COPs and I hope that is it, but I really have my doubts.

 

Sorry if i missed it, but did you try return to stock & reflash. (Completely lear out the KAM with a hard reset).

Does this also occur while in stock tune?

There is the remote possibility of the PCM itself going bad, or connections to it. For example, the drivers used to pulse the Cops are internal, draw huge amounts of current (albeit very briefly), and have a number of independent grounds in the PCM harness. Any problems / degradation could surface as the duty cycle goes up (more average load on the driver circuits, hence more potential voltage drop). I would think the PCM would trap these things, but perhaps not.

Just a thought. One thing at a time, Jim.

Good luck.

 

After reading all these posts I think I'll be replacing my COP's as my truck has been doing this off and on for awhile. Before and after the tranny went.

On 87, 89, & 93 oct fuel. Only mods performance wise are a CAI & exhaust.

I have 61,000 miles on the truck...

Everytime I've took it to ford telling them what was going on they said they found nothing. Even a few months ago when it went in for the trains... GRRR


Anyway now that i'm out of warranty... And there's no way ford will find it let alone cover it at this point.

What are good COP's to get? About how much am I looking at if I replace all 8

It's an 06 FX4 with a 5.4L

 

Have you checked your fuel pressure while this is going on? If the pump is getting weak the sudden demand might make the pump struggle causing a low flow and loss of power. The other thing could be a clogged pick up screen.

 

I have not returned to stock. I did not see how the problem could be tune related. I will do that and see what happens.

This started right after a rain. Under the hood, you can see where water gets picked up and thorwn on top of the engine and the underside of the hood. I am wondering if water got on one or more coils, causing a crack. Still, if that is the case, why did it not throw a code?

 

I have these on the way.

http://cgi.ebay.com/ebaymotors/NEW-I...item5d266640eb

 

Nope. The drivers are solid state. The coils are tiny inductors. The time taken to delta that rev is an eternity in comparison. Those coils also fire multiple times per ignition stroke, with ease - This is a sophisticated Delphi multi-spark ignition capable of many more revs than this truck can produce.

But yes... please DO install them for him ;-))

 

Then say that! ( could not resist, as I did not see it mentioned initially - and it's im-po-tant)

Not sure it's tune tune either - but that's part of the process of simplification / elimination.

Scientific method, remember?

 

BlueJay i had a similar thing like this happen to me. i have 50k miles on mine. I only noticed it also when it was cold out and id try to get to passing gear while already moving. When i went from a dead stop nothing until high rpms. I was due for an oil change so while i was there, i just had them change my fuel filter and air filter as well. So far ive had no problems since. Because of all the electronic things on these trucks the dealer said without a light they would never be able to find a fault code to diagnose...Not sure how true that is, so i went with the next route which i state above. If it does it again, ill do new spark plugs. ive never changed them yet.

 

The reason I had not said it before is, it has done this for 5 years with no problem. Doesn't mean that it did not cause this problem, but I wanted to see if everyone thought it was a coil BEFORE that was known, rather than just jumping to that conclusion.

 

...sneaky old bastige

 

You'll get there one day! Soon!

 

Always try the easy fixes first.
I had a similar problem with a tuner and it was shift points and WOT program issues. Never threw any codes. My problem was just as you describe. Normal acceleration ok...WOT at any speed and it bogged down or bucked hard.

Before you swap any parts why not try to put it back to stock and eliminate simple stuff. If it's not you wasted some time...if it is you will waste money and time.