Tomorrow

Hello everyone! Been a long time lurker reading info about trucks here for a while. I have a 2005 f150 5.4 with 170k on the clock.

Cliff notes I had a miss at low highway speeds about a week ago. The plugs only have about 30k on them so I decided to change the coils. Also decided since I was in there might as well change the plugs.

Well after plug/coil change I am getting a mis fire on #4. I followed other post directions about grease. Used motorcraft plugs and coils, but am still getting a miss on #4. This morning. Before class I even swapped the #4 plug/coil/injector with #1. Truck ran great for a few miles. Had power no stumble and then it returned. Threw code p0304 again.

I am really stumped on this. I have made sure I am not leaking coolant onto the coil, tried the switch method, and everything is new. Double and triple checked all connections. Still failing on #4.

Anyone have any ideas? Taking it to the shop is not in the budget right now as the plugs/coils kinda set this college guy back a bit.

techrep

iTrader: (1)

check the wires to the COP

MGD

Hi.

Wellsir - what left is the PCM drivers for #4 COP and #4 injector. Plus the harness for same. Difficult to check yerself without proper diag tools.

Further - may need to borescope the cylinder.

BTW -

2005 5.4L 3V's are in a high-risk category - read this and get them checked asap:

http://ww2.justanswer.com/uploads/sd...229_r07m08.pdf

EDIT - other items to check - cam followers for #4 and compression check on # 4.

good luck
MGD

Tomorrow

I will look into injectors, but I have already tried swapping locations and I am over the 120k.

Just left class and now it's something totally new. Truck idles pretty good now. Not 100% but better than before plugs/coils. Still has moments where it feels like it's dropping down a cylinder.

When you accelerate now it makes this strange schreachy noise. Not a constant nearly like a tap tap tap. Power is not fully back either. The noise is rather high pitched. Almost like nails on a chalk board but like I said it's not a constant just a tap tap tap rythym if you could imagine.

Tomorrow

The AFRP is b38-42 psi according to my edge. So far no new codes.

rubbinsracin

I had same problem on same cylinder. Sometimes its user error. In my case the plug wasnt fully screwed in on #4 and I had a seperate error on other plugs, not getting the connection back tight to the wiring harness and not putting grease on certain boots. opps...

1. pull the plug and check it. make sure it does not have any antisieze down at the electrode. re install making sure you have it tight and your wrench is not just binding up. (i used a misalignment knuckle and it was binding up making me think the plug was tight)

2. Put dielectric grease in the tip of the boot.

3. be careful when reinstalling the boot that you dont get any debris that is laying on or around the motor in the grease on the boot

4. make sure you have you COP tightened all the way down and that the wrench isnt just binding.

5. make sure you have the connection from the wiring harness to the boot fully clipped in. I did not have it completly tight on #8 and was getting a random misfire after I hit a bump. After I got it fully "clicked" into position the misfire went away.

Tomorrow

I am gonna "dive" back into it tomorrow morning. Hope I can get this figured out as I had plans out of town next week.

Thanks everyone for the replies. If anyone has any other ideas plz send them this way.

Tomorrow

Well this morning I had a friend who is a mechanic come over and give me his thoughts.

Tested the coil on #4 (coil was good). Swapped the injector again for another known good one. For good measure we replaced the plug on #4 again. He recommended a new wire pigtail so we went to ford and got a new one ($68 and some change for 2 wires and a piece of plastic). He installed the new pigtail. End result still no fire to #4. Idle has gone back to the crapper. The noise that was present yesterday went away on my way home from work. Truck is running very poorly. He has done many f150 plug changes before and never seen this issue. Has him stumped as well.

I am really short on ideas and money to fix this problem. The truck ran fine till about 50-55 before all this. Now with brand new motorcraft parts it runs like total crap.

Anyone have any other ideas? I can really think of only 2 left that is the PCM or a complete engine harness, both are a little out of the price range right now.

MGD

Hi.

As I mentioned earlirer - borescope the cylinder.

Are you absolutely sure nothing fell into the #4 cylinder? I for one do not believe in coincidence: plug change then poor running and misfire #4?

How was the COP tested? Needs to be done under load - a simple ohmmeter check is useless ( except as a go/no go shorted/open test) as the failure typically occurs while the COP is active (high voltage winding breakdown).

Harness integrity, PCM I/O to COPs, injectors, etc needs a facility to diagnose properly.

I fear you may need to spend $ on a dealer diagnostic. The longer you wait, the more raw fuel is being dumped into the cats ( which eventually ruins them), washing down the cylinder wall (robbing it of lubrication) and diluting yer crankcase oil. A diagnostic expenditure may end up being less costly in the long run.

good luck

MGD

Tomorrow

I will scope the cylinder tomorrow (have that tool but it's in my dad's boat stall).

Coil was ohm tested and was swapped with a known working coil.

I am trying not to drive the truck when possible as I know cats is another expense I do not need.

Hope i can make some head way tomorrow before I have to give in and take it to the dealer.