Sadly checking resistance isn't as reliable as its thought to be. I've had failed COP's test good on a DC resistance check.

 

Is that with a regular DMM? I wonder if a megger would work to check them with.

 

It might although for whatever reason the typically available DVM most of us have or use will show open or closed coils even though the induction function still won't work as needed.

Its highly ill-advised to suggest testing these the old school way but I'll describe it anyway. Remove COP from plug leaving boot, contact spring and wiring harness connector intact. Hold the COP with an insulated plier etc close to a grounding point and crank the engine. If the coil is good it will throw a spark--if not then something is wrong.

Before COP's this sort of test would give a fair indication if energy was being delivered to the plug.

Wakeon also makes an inductive detection device that can be used to test COP's merely by touching a pad to the top of the COP case. Almost bought one for new cheap but because this is a rather rear situation it didn't seem like a tool I really needed.

Not that there's anything wrong with owning tools not needed constantly right?

 

My 2000 ford keeps blowing # 4 coil any ideas.

 

Read preceding posts---they were created in order to be helpful and so far have covered most every common issue or cause of failed COP's.

 

My question is, after one coil goes out (#7 in my case) does that mean that the rest may be on their way out?

In other words, is it usually wise to replace all of them?

2008 5.4 expedition xlt

 

I am having coil problems as well. I bought Accel and got 18,000 miles out of them before they started going crazy. i spoke with my local Ford dealer mechanic and he said he has never seen a coil pac except the OEM last any length of time. Tomorrow I am biting the bullet and buying OEM. I can't pull my work trailer on 6 cylinders and sputtering. I used some of the Grantelli products on a 2004 H2 Hummer and only caused problems. Even with lifetime warranty , enough is enough.

 

No---one that has failed doesn't tend to signify the remainder are ready to go too.

Time after time we read where something cheap fails especially aftermarket COP's. I too used Granatelli's back in 2008---also never again. Since that time and on another E250 failed COP's are replaced with either MotorCraft or NAPA---both costing me just about $50 each. Oddly enough they seem to last..........

 

Thanks for the reply jwa.

 

Went by the local Ford Dealer on Monday and picked up 8 OEM coil packs at $76 each. An hour later, all my problems are gone. Today I pulled my 8000 pound JD backhoe and worked the engine pretty hard. Before the coil pack change , I would get a over fueling code, its gone too. I wish I had not wasted my money on the "yellow " coils,

 

More often than with any other brand Accel COP's are reported to have issues, typically a short time after being put into service.

That's not to say many aren't in use and working just fine but we rarely hear of repeated problems with the brands we've all learned are better over the longer term. Sure they're more expensive but what does reliability and dependability matter to us? If so I'll pay the extra and not have to "hope" everything will be fine and dandy.

 

I've managed to get cylinder 3 off but can't get cylinder one coil pack to come off. I've been cranking for an hour. The bolt won't back out or let go. Any tricks that can help me. Thanks

 

The threaded insert that the COP hold-down bolt threads into is spinning inside its casting. My V10 did that to me a couple of years ago.

Had to drill the bolt head off, then drilled out the insert and old screw at one pass, then re-threaded with the next larger bolt size. Now, one COP has a larger diameter bolt and larger head but it works.

 

I believe my problem is moisture getting in there due to leaking intake gasket, which seems to be a problem in a lot of these models.

 

Good point, also this is a year old thread but well deserved bump. I've had good luck with eBay coils on the fleet some with more than 50k on a set. Also routine maintnace by changing your COP boots and springs every 30-50k will make a cop last.