i got this code a few days ago, i pulled cyliner 1 spark plug really bad so replaced, erased the code, drove a round for a while, p0301 came back, so i swapped cylinder 1 COP with cylinder 2 erased code drove a round cade p0301 came back. my last resort was to swap fuel injectors also did that erased codes, p0301 came back. the trouble started helf way through our return trip pulling our travel trailer hence why the spark plug was so bad, the expy is a 2002 4.6l please help i'm losing my mind

 

4.6L with COPS? You sure?

 

well there are no spark plug wired, just a spring that goes to the probally one inch round componet that i'm assuming is the coil and i has a plug off it. there is one for each cylinder

 

Like this... - my bad, I see some 4.6's have these things too..

So - if it's not the coil, not the plug then maybe a little more detail? In what way did the plug look bad? What symptoms when running?

 

You might have a broken valve spring on #1

 

How do you guys get these codes. I know in my Intrepid it is done with turning the key to accesory 3 times, and the codes come up on the digital odometer. But how are they obtained on an Expedition? (I just bought mine, so sorry if this is a stupid question) it's a 98' with a regular non digital odometer.

 

If you find out the problem please post back the results. My '03 is an early build with an '02 4.6.

I keep getting a p0305. I have changed all COP's, new plug and new injector on #5, and still a dead miss when first started, and an intermittent miss when warm.

Lord I hope it is a harness or PCM. I sure don't want to pull the head.

 

You could check compression on that cylinder.

Also, if you have an oscilloscope, try to compare pulses with the bad cyl injector and others.

 

Same thing happened to me on # 3 cylinder while towing a box trailer. Turned out to be a burnt valve. I have the same engine. My spark plug pratically exploded. No tip left on it. It messed up my valve pretty bad. It sounded like the engine leaned out. I had just gotten gas and was accelerating onto the freeway when it happened. It sucks when that happens. Good luck.

 

Is there an easy way to test a COP?

 

did you check to see if the injector was getting a good power supply, also check for a manifold vacuun leak, if you have access to a scanner you can look at your short and long term fuel trims they should be around "0"

 

Easy test is to swap the bad COP with a good one.

 

ok here is the quick description of what the problem was a leaking intake valve on cylider one, so the head came off and luckly it did not damage the valve ( not bent or anything) ground the valve seat and slapped it back together

 

Just browsing through the forum and saw your posts. I am a ASE Certified Master Technician and I work on these things all of the time. I've seen guys change out the engine trying to chase this problem. The problem keeps coming back. I'll share my findings with you. On nearly 99% of the ones I have had in the shop with this problem it has been a clogged injector. Not completely resricted but partially clogged. Even after changing the injector the problem returns.

Certain chemicals in fuel additives (mostly the ones added at the fuel plants) cause the rubber lining of the flex hoses used in various locations on the vehicle to break down and debris travels into the injector rail. Now on most return fuel systems it is pumped back to the tank and is filtered by the pump sock and fuel filter. On returnless systems the build-up developes in the fuel rail. Then of course it eventually makes its way to the injector and gets trapped. Each injector has a small screen at the input connector.

I'm not saying this is your problem, but I have found many of them to be the case. What I do to correct and prevent the issue is to pull ALL the injectors making note of location and inspect them for debris at the screen. A simple can of intake cleaner will clean the debris out. Wear some safety glasses though. You wouldn't want that stuff to shoot back up in your eyes. You can take my word on that, it burns like hell. Second I install a inline fuel filter in the supply line (on return systems it is the larger of the two lines going to the fuel rail). Reinstall your injectors and leave the problem behind you.

I hope this helps you or anyone else. Goodluck!

 

robertsautomotive.

I want to thank you for your informative post. This is something so simple, yet so important. I did not know of the fuel line breakdown, and newer gave the consequenses of a returnless fuel system any thought.

Thanks for your post.