PLEASE HELP! My mechanic is supposed to be awesome at overhauling/rebuilding 5.4l motor hence why i went to him when i was told to i needed to do so when i started having problems with mine. I had a full overhaul done on my motor. since then it may go a week it may go two but it inevitably has at least one coil pack go out. im frustrated please help me get informed when i go to him with this Monday.
Anytime an engine is rebuilt, it has to be removed and reinstalled in the vehicle.
If a ground connection between the engine and body/chassis is missed, it can cause electrical problems.
Tester
My first guess is a bad plug wire. Second guess is a Bosch plug with a broken electrode.
This is coil-on-plug engine.
Tester
Could it be that after years of use and possibly oil saturated the coils are in the process of failing one by one? Maybe a thorough job of engine replacement should include new COPs @Tester. That type ignition was just beginning to show up in my shop when I closed my box and went home and the only failures that come to mind were due to oil puddling in the plug wells.
Here’s a few guesses … Make sure the CP’s are mounted the same way they were installed at the factory; there’s a heat-sink component to the mounting method probably. If the spark plug gap is too wide, that increases the voltage needed for the spark , and that can damage the coil packs. Make sure the spark plugs are oem, the right part number, gapped correctly, and in pristine condition. And the wires are in good shape, no visible cracking of the insulation when you twist them. When it is pitch-dark open the hood with the engine running at idle and look for any signs of visible sparking inside the engine compartment.
I don’t know about anyone else?
But when I rebuild an engine, the plugs and gaskets are replaced.
Tester
Maybe the OP could provide info about how much this rebuild cost. That’s not meant to be nosey; only to get an idea of how well it was rebuilt.
If the coils are dying then the plugs should be considered. If new plugs were installed then maybe there’s a compression issue which is causing the plugs to misfire and which in turn is killing the coils.
If the old plugs were left in a new engine; then ugh…
There’s no heat-sink involved when replacing coils on this engine.
Factory plugs literally can’t be gapped on this application . . . unless you want to wail on it with a sledgehammer
http://www.rockauto.com/catalog/moreinfo.php?pk=2347190&jnid=299&jpid=0
Although I essentially disagree with the idea of looking for sparking with the hood open on this particular application . . . the plugs are so far down in the hole, I doubt you’d see any sparking, even if the boot was torn . . . I have used that method to discover a bad coil wire on an Astro van, which has an old-school coil, igniter and distributor
When a coil goes out, is that the only one that gets changed?
How many have gone out?
Has it ever been the same one twice?
Coils, being built on very well controlled manufacturing lines, rend to have very similar lifespans. Usually when an aging coil dies, it’s prudent to consider changing the others at the same time. There’s not enough detail in your post to suggest whether that may be the issue here, but if it is a possibility it’s worth thinking about.
The other possibility is a high voltage problem. If the alternator is producing higher than normal spikes of voltage (like in a bad rectifier) it can kill coils. Has this been looked into?
Post back.
Here’s another wild guess for why the coils are repeatedly failing. I wonder, does the computerized ignition system on a vehicle like this adjust the coil voltage to be higher when it is cold or on cold starts? The idea would be to provide an extra healthy spark for those conditions. Seems likely, as that hot-spark technique is even done on my 40 year old Ford truck with a conventional points/capacitor/single-coil ignition system. If so, maybe the ignition system is thinking it needs to provide a hot spark all the time, instead of just when the engine or air temp is cold. Good idea to check the engine coolant and intake air temp sensors.
These are WELL KNOWN for this issue. When one coil over plug goes…the other ones will begin to fail one after the other. Ive replaced countless COP parts on Fords… VW also had an issue similar but they recalled the coils… all I had to do was bring the car to the dealer and they replaced all of mine for free…which was unusual for me being a mechanic, but I suffered through the indignity.
As far as your Ford? You will find that the coils will all fail…one after the other. Its a wonder Ford doesnt recall them…or maybe they have? I repaired the same truck you mentioned this week…for the SAME issue… I told the guy that I can patch you up here and now with one coil…but they are all going to fail one after the other. I was correct. The fix is obvious, what isnt obvious is whether Ford will cover the replacement or not.
Blackbird