Hi all,

I'm new on the forum. But I have been searching and reading for the better part of two days now, and finally had to register so I could seek some advice.

My 2005 F150 4.6L started misfiring Monday morning. It has about 175,000 miles on it, and I bought it a year ago when it had about 154,000 on it.

The engine was lurching/hesitating at idle and under acceleration, but no CEL popped up. I drove it to work, about 25 miles, and then back home 25 miles. I do have a code reader handy, so I hooked it up despite the lack of CEL.

I got the P0307 and P0174 codes. So, I got me a new COP, new plug and set out to changing them. I did test to insure I had spark, I did a NOID test on the Fuel injector plug and that works fine.

I'm at a complete loss here. My truck is acting like it wants to stall and it's a very defined hesitation/misfire under acceleration. I can, however, drive it when I first start it up in the morning for about a mile before any of these issues start up again.

Does anyone have any ideas for me?

Like I said, I spent the better part of two days on here searching and trying tests as best as I could before I bothered putting up this post.

I appreciate any help!

 

It's possible you could have a failed injector.


You have misfire on #7 and Bank 2 lean codes.
If you have spark, but still get the misfire code, that coupled with the bank lean code would lead me to suspect the injector, provided you have ruled out an intake manifold leak on Bank 2.

You could try to swap the #7 injector to another position and see of the misfire code follows before buying an injector.

 

I'll try swapping injectors. How would i test for a manifold leak?

 

https://www.youtube.com/watch?v=uW3Zw_EH5PU

Older car, but the theory is the same.
You also want to double check for vacuum leaks as well.

Pretty easy stuff compared to pulling the fuel rail and moving an injector.
Rule out the easy stuff first.

 

So this evening when I got home from work I did the following:

Swapped injector 6 for injector 7. Noticed the o-ring on the original #6 was cut, got new o rings on both injectors. Then I got the codes for lean on bank 1 and bank 2. Also, misfired on cyl 7.

Got back under the hood, noticed the #7 injector wasn't seated all the way down so I adjusted that, cleared the codes and went for a ride.

Still got the misfire 7 and lean codes.

Curious, I pulled the connection from injector 7 while the engine was running. Nothing changed.

So I pulled the connection from injector 6. The engine reacted immediately. I plugged it back in, scanned the codes and got the code for Injector 7 P0207

Hmm. On a whim, since I had one new coil on hand. I changed the COP on cylinder 6. It was ugly. It definitely needs a new plug as well, but I didn't have one on hand this evening. Anyway, I installed the new COP on 6 with plenty of dielectric grease. Cleared all the codes and let it run at idle for about 5 minutes.

In the past, it would put up a pre-code of something within that amount of time. This time, NOTHING showed.

So I test drove it about 5 miles. Also in the past, the stuttering/misfiring was really noticeable at about a mile or so out. I couldn't get it to do anything on this quick little drive. Got it back home, scanned again, and so far no codes are showing.

I'm thinking I'm on the right track, and I have plans to do a full tune up this weekend with new plugs and cop's all the way around. I just need to get it running well enough to avoid serious damage until tomorrow evening. Then I have two full days to tinker on it.

I appreciate the help and if anyone has anything to add or suggest, I'm definitely all ears.