4.6 XLT 2003 P0306 and P0316 help!!!!

[ronixd]

My 4.6 XLT 2003 has codes p0306 and a p0316.


I have put on a new dorman intake manifold, new motorcraft plugs, new cop boots.

I have moved the cops and fuel injectors around but the misfire stays in cylinder 6. Pulled all plugs and all look good.

Compression for 1-4 is 190psi, 5-8 170psi. I hooked up a vacuum gauge to the brake booster vacuum line, upon cold start up gauge starts at 180inhg then immediately drops to 140inhg for around 4-6 seconds then climbs back to 180inhg and steadily stays there as it should. this only happens during a cold start or after the engine being off for around 30 min. I could post a video of the vacuum gauge but I don't know how.


I am baffled and need help!

 

[Number4]

Test the wiring to #6 injector and coil.

 

[ronixd]

Test the wiring to #6 injector and coil.

put a noid light on cop wiring and they look all uniform to me. have not tested injector wiring yet. any suggestions on how to go about it?

 

[ronixd]

Anybody?

 

[ronixd]

Replaced both cylinder 6 lash adjusters. Still have P0306 and P0316!

 

[ronixd]

Update, i replaced the broken fuel injector and cop clips and the camshaft sensor. Still have p0306 and p0316 codes!! Help!!

 

[Number4]

Safe to assume you cleared the codes after each repair?

 

[ronixd]

Safe to assume you cleared the codes after each repair?

Hi, i usually drive the car a few days for a couple of hundred miles to see if the code goes away, if it does not, I manually clear it.

 

[Drewmcg]

You might try slipping off the two-wire clip for the Crankcase Position Sensor, spraying the harness (female) and CPS with electronic cleaner, and using some dielectric grease on the harness before putting it back on.

I don't know the 4.6, but you might try removing the (new) plug from #6 and swapping with another cylinder. Reason: you could have cracked the porcelain on the new #6 plug when installing. By swapping it, if the misfire stays only in #6 you will have truly eliminated the plug as an issue.

 

[Drewmcg]

Also... you probably saw this, but sidziner had luck replacing all 8 COPs with a cheap set he bought on Amazon ($33 for the entire set !--see his thread). How old are the COPs?

 

[ronixd]

Also... you probably saw this, but sidziner had luck replacing all 8 COPs with a cheap set he bought on Amazon ($33 for the entire set !--see his thread). How old are the COPs?

Thank you for the reply. Yes i have moved the plugs around, i also replaced the camshaft sensor. Cleaned all connectors and used dielectric grease when reinstalling. cleared the codes and the p0306 and p0316 always comes back after a couple of start ups. And yes i saw the sidzingers post, and i ordered the set he recommended and installed it. I thought it solved the problem!!! But i was so bummed out when the code came back after a week of regular driving.

 

[ROBinGa]

Did you say you have changed the plug itself? One other thing, can you inspect the wire and connector that connects to the COP to make sure nothing is nicked or corroded in the connector? If possible trace that wiring for cylinder 6 as far back as possible in the wire loom for a nick in the insulation or kink or something. If it's always cylinder 6 then it has to be something like that if you are swapping COPs and other components but misfire is always 6

 

[ronixd]

Did you say you have changed the plug itself? One other thing, can you inspect the wire and connector that connects to the COP to make sure nothing is nicked or corroded in the connector? If possible trace that wiring for cylinder 6 as far back as possible in the wire loom for a nick in the insulation or kink or something. If it's always cylinder 6 then it has to be something like that if you are swapping COPs and other components but misfire is always 6

Yes new plugs all around. I also replaced the bad connectors. Yes i replaced the camshaft sensor. Will follow your advise on the wire loom/harness inspection. Thanks. Anymore advise is very much welcome keep them coming!!!!!