Three weeks ago I changed all the plugs and coils on my truck. I used Motorcraft plugs and coils were from Uneek. Plugs were torqued down to 28 ft lbs with no antiseize and i used dielectric grease in the boots, makings sure the ends of the spring were clear of the grease to make contact with the plug.

Well 3 weeks/1000 miles later the engine has developed the dreaded low grade misfire. Its only been a couple days with this now but its missing when I'm easy on the gas right when the tranny shifts to OD - from 40 to 55 mph. I've ran it to 60 slowing back down to 40 with no brakes and back up to 60 again, then slowing to 40 again and trying to hold on the misses a few times and haven't had any luck getting a CEL. I scanned the computer for codes this morning and unfortunately I have no codes.

Does anyone have any new tricks to identify which coil could be the week one? I'd hate to swap them out one at a time with an original to track the problem down, but I also don't want to order a new set of 8, and I don't want to put the 8 original back in. And I also don't want to go to the dealer and pay top dollar for the mode 6 data test. So if anyone has any new methods that have worked to throw a CEL with a low grade misfire, please let it be known!

 

be patient it'll give you a cel, might have already it could be stored as pending. I've read c couple methods but it just seems like you put a few miles on it and it gives up the hard code..

 

I put on about 50 hwy miles on the truck each day so I'm hoping it'll eventually throw a code. Do you know if its hard on the engine to put a high number of miles on with the low grade misfire?

 

I'm sure you wont be letting it go to long. While it isnt the best for the engine, going a few days aint going to hurt it. Try fluctuating your speed. Some say driving up a hill slowly locks in the code. Some say getting up to around 50 and slowly decreasing speed does it.

 

Calling all cops to be on the look out....Vehicle identified as a late model F150, Suspected drunk driver, erratic behavior at high speeds, then decreasing speeds to below limit. Was seen at very low speeds approaching sterling hill causing massive traffic stalls.

After being pulled over...cop asks the driver if hes been drinking...

"uh, No sir... just trying to get my code to show up on a low grade misfire"

 

With a low grade missfire you may not throw a code. Its just not enough consistently to recognize it. I take it you had no missfires with the old coils? If thats so then replace four on one bank with old coils If you still have a miss then you can suspect the opposite bank. Now either way you are down to four suspect coils. Try replacing one of them at a time with a known good coil from the opposite bank until you find the suspect new coil.

 

Correct - there was no miss with the old coils. If I can't get the truck to throw a code within a week or so I'm goin to try what you are suggesting.

 

ok i got 2 codes...no good internet connection though, just the phone, and i cant get the search to work.....p0304 and p1000. can anyone give me some help?

 

Yes , replace #4 coil, = fixed.

You can purchase a complete new set here -

http://cgi.ebay.com/ebaymotors/NEW-I...Q5fAccessories

 

replaced # 4 coil....took 4 a 4 mile drive around the block.....fixed 4 now.....you da man brew! thank you! time 4 a beer!

 

ok p1000 code still there but its drivin fine......?

 

That's okay 1000 will clear on it's own, - when all monitors have had a chance to run. That comes about when you reboot the PCM. It takes a few drive cycles for it to clear.

And no problem

 

The misfire is back No codes yet but the misfire is back. After I took out coil # 4 last night I checked the tightness of the plug and it was torqued correctly. What are the odds of having multiple weak coils from Uneek?

 

It's possible, I get the coils from Global, not Uneek. Never tried them before.

 

i pulled the #4 plug today and i did notice some dielectric grease on the tip of the plug where the spring from the coil connects. i cleaned this up on this plug only and reinstalled...still missing from 40 to 60 mph in od though. maybe this is my problem on some of the other plugs.....why would this problem take 3 weeks/1000 miles to appear though?