Cylinder 1 Misfire. NOT plug,coil,or injector. Help

[Drae]

I had a 2003 with the 5.4 and a similar problem. Dealer ended up replacing the harness for the #1 plug and that fixed it.

My wife's 03 5.4 had the same issue where one of the pins became loose inside the ignition coil harness. I replaced it with one from O'Reillys. It was a ***** to do considering it wss cylinder 4 but it definitely cured that hiccup.

 

[BrinkExpo]

Did you check harness for #1 fuel injector? You need to be sure theirs power going to that injector. Putting sea foam, and all the other miracle fixes, is not going to get #1 bank right again. Before you dive into the valve train, make sure all with the fuel side, as well as the ignition side is sound. You said the dealer swapped out coil, and spark plug, and problem wasn't corrected. Depending on your patience and skill level, you can proceed with the members help, or you may choose to have a shop complete. We've all done it. Sometimes our time, and sanity outweigh frustration!

Sent from my N9131 using Tapatalk

Yes I replaced the plug, coil, and injector.

How do you check harness for #1 injector to make sure it is good?

 

[1955moose]

You can borrow/ buy a set of noid lights made for Ford, or use a volt/ohmmeter and check for voltage at plug. Noid lights are a small plug with a light in them that plugs into each part of harness. You can find procedure online.

Sent from my N9131 using Tapatalk

 

[1955moose]

Theirs a great article I just read on how to test your injectors on 4.6/5.4 with noid. Light. Might want to read it.

Sent from my N9131 using Tapatalk

 

[BrinkExpo]

When I replaced the injector it wasn’t fully seated and it definitely spit fuel out of there. I got it seated fully now and it doesn’t leak.

Is it still a good idea to check the harness for that injector?

 

[1955moose]

Depends, how's it running now?

Sent from my N9131 using Tapatalk

 

[BrinkExpo]

Depends, how's it running now?

Sent from my N9131 using Tapatalk

The same. It starts great, idles great, and drives great. The misfire only happens under hard acceleration at 3,000 RPM and above and it is very noticeable.

 

[1955moose]

Your describing an electrical issue now. You stated earlier that the dealer said nothing was wrong with plug, coil, etc, and even swapped it around. If your getting a hard miss that progresses with speed, that has a hard jerking feeling, like a light switch going on/off that's usually secondary ignition, Ie coil/ boot/ spark plug. Fuel symptoms are usually a little softer feeling. I'd still isolate all fuel delivery problems, to be sure. I know this will sound a little nuts, but you also stated dealer said compression was good, how did they test it? Let us know. Any one else want to join the party? What am I missing? Fuel, spark, compression?


Sent from my N9131 using Tapatalk

 

[1955moose]

Check the injector plug for voltage, and pulse, just to rule out. If your 100 percent sure that your spark plug and coil are sound, and fuel is also, their may be an issue with the engine itself. Possibly a bad valve on that cylinder. Let us know.

Sent from my N9131 using Tapatalk

 

[BrinkExpo]

Dealer said relative compression was good when he hooked the computer up but could still have broken valve spring that’s doesn’t allow it to close at higher rpm.

What is the best way to check valve spring?

 

[1955moose]

Do a compression test of that cylinder, actually I would do all banks to be sure their all balanced within each other and pull valve cover and inspect it visually. I know the new technology can show basic engine balance, and compression through scanners, but nothing like doing a full eight cylinders compression test with a quality screw in gauge like Snap on, or Matco. A cylinder balance test with a pressurized gauge is standard procedure with any compression issue. Tells you if you've got bad valve, valve guide seals or rings. A weak valve spring is a little tougher to diagnose. Unless it's visable, like laying in the valve cover, a weak valve spring would usually require pulling that cylinder head, dismantling that suspect spring, and tensile test it. Not a common issue, but anythings possible.

Sent from my N9131 using Tapatalk

 

[stamp11127]

Looking back at your first post, what criteria did the dealer use to determine it is cylinder #1#if there were no codes?

 

[BrinkExpo]

Looking back at your first post, what criteria did the dealer use to determine it is cylinder #1#if there were no codes?

He had his computer plugged in and when I drove the truck and got it to misfire, I could see cylinder 1 spike on his graph when all the others remained consistent. It did this several times.

Not sure what this was reading but that’s the best I can explain.

 

[BrinkExpo]

Do a compression test of that cylinder, actually I would do all banks to be sure their all balanced within each other and pull valve cover and inspect it visually. I know the new technology can show basic engine balance, and compression through scanners, but nothing like doing a full eight cylinders compression test with a quality screw in gauge like Snap on, or Matco. A cylinder balance test with a pressurized gauge is standard procedure with any compression issue. Tells you if you've got bad valve, valve guide seals or rings. A weak valve spring is a little tougher to diagnose. Unless it's visable, like laying in the valve cover, a weak valve spring would usually require pulling that cylinder head, dismantling that suspect spring, and tensile test it. Not a common issue, but anythings possible.

Sent from my N9131 using Tapatalk

Are most shops able to do a compression test with a quality screw in gauge to learn more of what’s going on or is the dealer the best place?

 

[1955moose]

Of course they can. It's difficult to get at the back cylinders, that's an understatement. But any decent repair facility should be able to do it. What bugs me is you now stated his scanner had a kv spike. Guys correct me if I'm wrong, but that's generally a secondary ignition malfunction!

Sent from my N9131 using Tapatalk

 

[BrinkExpo]

I brought it to the dealer again to have them really dive into this and they said the next step was to take passenger valve cover off and check for broken rocker arm or valve spring. We did that and everything looks great. Put it back together and it is misfiring on multiple cylinders on passenger side(it is hard to read the misfires above 2500 RPMS I was told). They replaced 1&2&3 plugs and moved coils around and it still misfires. They also said that the misfires happens between 3000 and 4500 RPMS and then it clears up. Fuel injectors are spraying fine. Fuel injector harness looks good. Relative compression is good.

The dealer is at a loss now and doesn't even know what to try. Possibly a clogged catalytic converter but they said normally a whole bank of cylinders misfires if that is the case.

I do not want to throw anymore money at this issue but it is bugging me and I don't want it to leave my wife on the side of the road with our 4 kids. Any other thoughts? Or just drive the darn thing?

 

[1955moose]

Maybe I'm missing something here. One item that wasn't mentioned is the fuel pump control module. Usually a spark related issue gets worse as rpm climbs. That's why they usually show up at highway speeds. You state that it clears up above 4500, which is close to redline. Have the shop or someone check to see if the fuel pressure is fluctuating. A failing fpcm may be causing a starving sensation under load. The only other thing comes to mind would be a small pinhole in combustion chamber of #7 head, causing misfire of coolant and fuel trying to fire.

Sent from my N9131 using Tapatalk

 

[BrinkExpo]

I replace the fuel pump control module last year.

 

[BrinkExpo]

That is in the back on the drivers side frame right?

 

[stamp11127]

What was being monitored that showed the spike?

I don't see where a kv spike was mentioned.

Did they compare the signals between the crank and cam position sensors while it was misfiring?