My "ride" is a 97' Expy 5.4EB and I seem to have a slight engine stumble
around 1300-1400 rpm's. I want to check the coilpacks for proper operation but I do not have the "specs" to do that. Can I measure the resistance across the contacts for a start? What should I be looking for?

 

I'd kinda like to know too...

 

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primary .3-1.0 ohms and secondary 8-11.5 Kohms

 

Coryrhonda's specs are for the Electronic Intergrated Ingnitions systems only. If you have the Coil over plug setup the Primary should read @ 0.5 ohms which depending on how good a meter you have may just read dead short. The Secondary should read @5.5k ohms, you need to carefully remove the rubber boot to measure this, if you measure at the tip of the boot to the piece that sits on the spark plug it will be more like 8.2K ohms. If it turns out you need one or some, try ebay for some good deals.

On a side note; i had a similar stumble on my 5.4 motor, turned out that the connector had cracked and was not locking onto the coil and would miss under acceleration.

 

Sounds like a great solution - I have a ohm/voltage meter with the probes- but how do I test my coil packs? With the truck running and what is the primary and secondary? Can you guys walk me through it. I have been so plagued by coil pack probelms- and would like to test these things at home but don't know how. Thanks

 

I take it you have not done a spark plug change. So my suggestion would be to set aside a day you can work on it without being in a hurry. Go down to the auto store and buy yourself a repair manual, generics are only @ $15 and although not very detail they do help. Also get a set of Motorcraft double platinums, (dont let them talk you into some gimic plug or bosch, if they dont have them go somewhere else.) Since your gonna remove the coils you might as well change the spark plugs. If you dont have a good tool selection go down and buy an array of extensions and univerals socket adapters, dont forget a tube of dialectric grease and antisease also pickup Digital multimeter if you dont have one.

Changing the plugs are alot of fun! expect 3-5 hrs for the first time on the 5.4 v8 and thats with no problems, of course depending on your skill level. But the plugs are kinda of hard to get to and seem almost impossible on the first try. But it is possible so just take your time and remove "most" the parts in your way, within reason. It will make for less frustration and less possible damage.

Your gonna need a 1/4 in socket and extension array as well to Manipulate into a position to remove the single 7mm bolt holding the coil on the plug. You need to remove the coils to test them. (you can also test the triggers going to the coils if you find no problems with the coils, see the repair manual.) The primary resistance check is dont at the connector part of the coil, you'll see 2 pins test it pin to pin. For the secondary resistance check carefully remove the rubber boot and test from the spring to one of the 2 pins at the connector end of the coil. And thats it, do it for the rest and the checks are done.

Now before you remove the plugs use either an air compressor or vacuum to clean around the plugs to make sure no rocks fall into the cylinder, it can get pretty dirty in their. Now manipulate your self and your arsenal of extensions and adapters to remove the plugs (you'll need a spark plug socket to remove the plug the one with the rubber insert that holds onto the plug) Theres a sticker in the engine area that says what the gap should be.

Remember its alot of fun and takes time, so dont get frustrated into breaking something in the process, just take your time and expect your arms to get all scratched up!, its doable and if you do it often you'll get good at it! Also you'll need something sturdy to stand on to reach some of the plugs.

happy wrenching.

 

rmac585: Hey- thanks for the feed back- I changed the plugs last two weeks ago- after a coil pack went down at #5 cylinder- so since I had to pull the fuel lines off I went ahead and replaced with motorcraft plugs- I have now had three coil packs go out on me - one at a time- two previously and one when I changed the plug- each time I've paid a shop $40 to put the truck on the machine to ID the cylinder. If this is going to be an ongoing thing $113 from the dealer for the coil pack- and $40 a pop each time one goes down- it can get expensive on me. So - I've got this coil pack sitting on my kitchen counter- but am balking at going back to the shop machine for instructions. How can I use my Ohm meter to find the little culprit - also can I drive the vehicle if its missing in the mean time or will I do damage? My Expy is just hanging out in the driveway while I try to figure out if I can find the right coil pack and replace it. Bill

 

rmac585- I read your post again- and it makes a lot of sense. At least I only have 6 coil packs left to test. Thank you for such a thorough and helpful response to my dilemma. I bought a voltage meter about two months ago to help my daughter with a science project- so the post on ohm meters and coil packs and resistance caught my eye- it is great having access to so many experienced people - thanks again-

 

Thanks for all the great info! I'll be testing my coil packs this weekend.

 

Remember, when you test with the ohm meter you are testing the coil windings. The boot could be "leaking" spark under load. You may want to buy new boots. I bought some made by Standard Products. I am going to see if the coils I took off are really bad....when i get some time..

 

Hey, I Checked my supposed- "bad" coil pack with the ohm meter- guess- what? the resistence is the same as the resistence on the brand new coil pack I just bought at the dealer- THEN - I took the boot off- and guess what- the
rubber was soft- much softer and spongier and less resilient than the NEW boot on my new coil pack- I think you are exactly right- if the resistence is the same- and the only difference in the coil packs is the turger of the boot- I'm going to start switching out the boots and save quite a bit of money on $113 coil packs. Thanks

 

Hey! I finally swapped back in one of the "bad" cops with a new boot. Cop is good! been 300 miles no miss yet! Why won't Ford just sell you what you need?