COP questions....

[csdangerous]

2001 XLT 4x4, 4.6, 151k miles. Just got a rough idle a few days ago. Scan shows P0308 cylinder 8 misfire code. From the looks of the COP's under the hood, they're either factory, or were replaced at dealership as they're Motorcraft, and they look old. My question is if I can replace just the one, or if I need to do them all. The price dictates that I wait a week and a half to do them all, but I still need to drive to work and back. I can replace the one now. Any ideas or suggestions ?

 

[Bedrck47]

First check the resistance of the #8 coil as compared to another coil. Also check the connector for the #8 coil. Make sure you have a good connection. Check the boot on the #8 coil. I once had a pin hole in a boot that was the cause of a misfire and all I had to replace was the boot. Use dielectric grease on all connections and on the boot wire

 

[Bedrck47]

with the mileage you have you may want to replace all the coils, boots and plugs

 

[IMINYOURCHAIR]

@dangerous (OP) what I like to do when I have a miss and suspect the coil (when COP) is move the coil to another cyl, clear the codes if any and read the live data on a scanner to see if the miss followed the part.

you can do a power balance test to check this too if you don't have a scanner. just crank the truck and let her idle, then unplug one injector at a time until one you unplug does not change the rough idle.

@roxy1225, what resistance is he going to expect from a good coil, what would you say would be the upper and lower limit acceptable for this test, resistance is a good suggestion but even when comparing to another coil there is a chance of having two that are on the far end of the spec, or even having each at the other end of the spec. good call to suggest that to be checked, just thought that having a spec would help the OP.

 

[Bedrck47]

check these video's on youtube

How to check your ford modular coil on a 4.6- 5.4- 6.8
Cylinder Misfires & Ignition Coil Testing

 

[Bedrck47]

sorry but I don't have the specs available. My suggestion to check resistance of the #8 with another coil would at least show if the coil was bad depending on the readings. this could be done with the least amount of work. If there was a great difference in the readings then I would suspect that the coil was the cause of the misfire. If the resistance readings were the same I would next suspect the boot or plug and would remove and replace both.

since the OP stated he would have to wait a week and a half to replace all of the coils I felt that this would be a fast way for him to find the problem and hopefully get the engine running on all 8 cylinders. Also if the boot is the cause of his problem the cost would be less than $10.00 to repair and when he did replace all the coils he then could have a spare boot which isn't a bad part to have on hand

 

[csdangerous]

thanks for the tips guys....youtube video was also helpful....i'll get started on it tomorrow and let you all know the score. thanks again.

 

[Bedrck47]

kindly keep the forum updated

 

[csdangerous]

ok...so #8 coil is shot...looked around and found a good price on plugs and coils at Rock Auto. anyone got any opinions on Denso coils with NGK plugs ?? 225 for all of it delivered to my house.

 

[Bedrck47]

just make sure you torque the new plugs to spec.

 

[csdangerous]

specs in the owners manual ? anyone know what they are off hand ? this will be new to me. haven't changed plugs on a modular motor yet. man i miss pushrods...

 

[Bedrck47]

16 to 20 ft lbs

 

[AskMeLater]

ok...so #8 coil is shot...looked around and found a good price on plugs and coils at Rock Auto. anyone got any opinions on Denso coils with NGK plugs ?? 225 for all of it delivered to my house.

FWIW, I installed the Denso coils on my '03 when I bought it earlier this year. Purchased from RA. Have put almost 9000 miles on them with no issues to report. Also, they are made in the USA, which is nice!
5% discount code (if you don't already have one): 2547534523703518

 

[csdangerous]

thanks for the specs. and thanks for the RA discount code. now i'm just waiting for the fun part...changing those bastards...

 

[csdangerous]

Coils from Araparts, and 8 NGK Iridium plugs for 135 shipped to my door. All the reviews I read on the web and F150 forum were positive for Araparts coils. Hoping I get a good batch.

 

[csdangerous]

So...changed COPs and plugs. Disconnect battery to reset CEL. The pig is running great all the way to work. Leave work, CEL comes back on. Think maybe I didn't leave battery disconnected long enough. Try it again. 30 more miles, light comes back on. Busy at work, time goes by...2 weeks or so, I go and have code read again. EGR problem. I'm driving home and suddenly an epiphany ! Get under the hood at 10 at night with a flash light and what do I see. A small red hard line and a small green hard line pulled out of the way and not reconnected to EGR valve and whatever the hell the other part is. Reconnect and start driving. 3 drive cycles later, light is gone. Pig is running like a champ. Man I feel like a Melvin. Gotta love it.