I pulled 2 of the COP's off tp change the plugs and was testing them while doing so and the primary resistance is measuring 1.3 Ohms. it did this on the 2 that I tested off the truck and the third i tested on the truck still. Are these bad? haynes says .55 Ohms. Should i look into replacing them and if so what should i use?

 

Does Haynes list a minimum and maximum resistance? That does seem somewhat high, but not necessarily a problem.

As far as what to replace them with, use Motorcraft. Its the only way to go.

 

i had 2 misfire codes on my f150. due to the high miles I replaced all of the cop's. I checked resistance on them and they were all the same and if I remebmer right they were about the same ohms as yours. if youre lookin to replace just the bad ones i would replace the cop on the cylinder that is giving you a misfire code. DEFINATLY USE MOTORCRAFT COIL PACKS. They are pretty pricey, but I used some chepos that I bought off ebay and they only made it 3 months and not even 1000 miles, so yeah, I got the oppertunity to do them twice

 

Did the new ones also have a resistence of 1.3 ohms?

 

i bought a set off e-bay for under $100. and they worked fine. Look just like the originals, except for the sticker on top.??????? i thought the add said life time warrenty? might check that out.

 

There is something that needs explaining about this.
.55 ohm is very low resistance.
The meter leads and connections to the coil is critical because even their resistance can be large enough to make the total much higher, leading to a false assumptions.
Next, you need to zero the meter on the Rx 1 scale to be sure of the meter's accuracy by adjusting the calibration contol if it is an analog type meter..
Lastly, the meters basic accuracy is a consideration.
Finally, testing a coil for resistance is not a good reliable indicator of it's health.
It could have shorted turns that your meter's resolution ability can't pick up.
Shorted turns reduces the coil's output that especally would show up as a miss under cruise conditions when light throttle is applied 'and' no code is set for this resulting condition. The explanation for it is a bit long, so just take it on faith.
A coil with radical real resistance out of tolerence would miss at all times with no need to measure because the cylinder would be identified from the code set.

 

Doing static resistance checks aren't worth much. Have an assistant start the engine. Put vehicle in "D" with foot on brake and lite pressure on gas pedal. Now you start pulling the COP connectors off and back on one at a time. You should notice the idle drop and the engine shake a little if the COP is GOOD. If it is defective there will be NO change. You can do this to all the connectors on the fuel injectors too. In 10 minutes you've checked all your COPs and injectors dynamically instead of a static test on the workbench.

 

agree with eallanboggs on this one. might not be the right or safe way but it's quick and easy.

 

if you have a good life ins. policy i would not let your wife run the gas and the brake...

 

He has two options: Stand in front of the engine during testing OR to the side. His wife will know how much he trusts her by where he stands. If he really trusts her he will stand in front of the engine regardless of whether or not she is the beneficiary on his life insurance policy. Conversely, he will know her intentions by how much gas she gives it.
All joking aside putting the trans. in Drive and adding some fuel loads the engine down which makes a misfire easier to detect. The Emergency Brake should also be used.

 

not sure didnt check

 

Respectfully, still the above is not a conclusive way to test any coil.
Here's why; the worst case operation for any coil is under lean fuel conditions. A load test such as purposed does not create this condition.
The worst case operating condition occurrs under 'light throttle' cruise conditions.
Under this condition the fuel is cut back, the timing is advanced and the EGR opens to admitt exhaust gas into the final mix causing air/fuel ratios as high as 20 to 1.
It's under these specific conditions the coils have to have enough reserve output to fire the lean mixture or a miss results.
A miss fire under any other conditions is either an outright coil failure, moisture, boot failure, plug failure, fuel feed, water in the fuel, injector or some combination of factors.
Those with digital engine monitors can see when cruise conditions are entered while driving. In the 45-65 mph speed range look at the ignition timing under very light throttle. You should see it go up to as high as 35° advance during those times indicating the EGR has opened as one of the parameters that happen to cause the timing to advance.
If just one coil has shorted turns, that cylinder will miss until you apply enough throttle, see the timing fall back (EGR closes), fuel richens up to the point the mix is easier to fire and the miss goes away until the next time the conditions are present.
Causual testing of coils won't show the fault and no code will be set.
The reason the code will not be set is the fault is not a hard fault and only shows during the above said conditions. The PCM cancels short term memory of the fault that normally would set a code,because it has cleared (comes and goes) and is not in long enough to cause a code.
You still won't know which coil is the cause.
The logic of reporting codes are such that only outright failure is instantly reported as a code and lamp or a record of enough hits that are not cancelled or you would see a CEL lamp for everything that happens.
However, with a scanner, often times a tech who knows what to look for might be able to see the record for each cylinder x (8).
The best way to test a single coil is an output stress test you can't do at home.
Another possible cause of 'stumble' is a dirty mass air meter.
Knowing this depth of how things work is the best way of having good success at trouble shooting.
You are dealing with total computer control and a lot of things are going on at any one instant in time that keeps varying the operating conditions vs load, throttle, temp, rpm etc.
Any other ways that result in a fix is usually luck and enough parts bought and replaced.

 

how long have you had them? talked to a couple of mechanics and they said they see people use these all the time, then when they start to fail they bring them into the shop thinking its something else. they told me to only use ford and they're not ford mechanics. I think the ones i bought on ebay did have a lifetime warranty, but i never want to put coil packs on this again so i went with the motorcraft. I heard people on here saying that changing them isnt that bad, im a heavy diesel technician and I dont think that i ever get that frustrated when im at work then i did changing them twice. i just took the 100 bucks as a lesson hard learned and would only use the motorcraft.

 

If I was a Ford owner(which I'm not)of a 97 to 03 F150 or Explorer or Expedition with DPFE EGR system my EGR would have been bypassed the day my warranty expired. I realize most guys can't figure out how that is done so that an EGR(P0401)DTC does NOT go set like I have done. I have no love loss for the EPA due to their wonderful inventions such as PCV and EGR. Most guys don't own a DVOM, Snap On Labscope, Power ProbeIII, TESlite, Scan Tool, etc. so for them the shadetree mechanic method I have suggested as limited it is in our high tech world of ECMs, PCMs, TCMs and more are the only alternative they have left. Not many guys who want to work on their own stuff and have the tools and ability to do so have a scan tool and assistant to drive the vehicle for them as they watch their scan tool for misfire counts as the ride down the highway at 45MPH. Nor can they spend the hundreds of hours studying ODBII theory as some of us have done. They just want their vehicle fixed and the SES lite to go out. Everything I've ever been taught tells me components fail under heavy load not at idle or deceleration when the EGR is commanded open. Adding timing at idle isn't needed. When you reach higher RPMs spark advance is needed due to the speed of the rotating assembly. I don't want anyone to get the impression this method is scientific in any way. It's not. I own all the high tech stuff so I can look at waveforms and misfire counts, but for the guys who don't pulling connectors is a trade off that has some merit and more often than not will get your truck back on the road firing on all 8 and no check engine lite illuminated.

 

Well said.