So I know I shouldnt complain since I have 511000 miles on my 3011 Ford F-150 with the 3.7 engine. But now things are starting to go, just changed the cats and want to change the 02 sensors but can't seem to get the clip to release the connection, is there an easy way to do it? Also I'm getting a 0403 code with number 4 cylinder misfire, already put new plugs and cools in , still getting it so next is the injectors! Is this an easy task or should I just let the dealership do it! Thanks

 

511000 miles??????? That's almost 100k a year!

P0403 isn't a misfire, that's an EGR code.

https://www.engine-codes.com/p0403_ford.html

 

Ahh that would explain it then I hadn't no idea where o got that it was a misfire code!! That explains why it didn't help changing the plugs and coils and yes though it's about 80000 a year it is a. 2011 and I'm actually now at 511989! And that's all my driving I drove it off the show room lot with 9 miles!! And as I've started to say these are the only issues I've had, well except new rear end at 400000 and for sone reason drivers side rear brake light and directional decided not to work anymore, tried rewiring them and nothing

 

And the code is p0304 not 403, unless I have cylinder damage which could be with mileage, I'm more inclined to think injectors! I hope it's not the engine, I want to get to a million miles with original engine and tranny

 

If you have changed the plugs and coils and are still getting a misfire, I'd do a compression test. With that many miles, I'd recommend you do it anyway. If it's good, then I'd look at injectors. You could swap the #4 injector with one of the other cylinders and see if the miss follows the injector or not.

 

Have you checked the connections to the COPs? at work we see equipment down all teh time due to one pin in a connector pushing back when we connect it. sometimes they are hard to see. You could also check continuity back to the PCM. EDIT: Found them. Hope this helps!


2011 3.7L COP wiring



2011 3.7L FI Wiring

 

Well I'm not equipped or have the knowledge to do a compression test, but wouldn't the smart thing to do change the 02 sensors An the injectors first before a compression test!! I only say this because the misfire is only occurring when idling or stopped at a ref light, I'm not showing any loss of power or speed even hauling my loaded trailer!
As for the 02 sensors how to you get the connectors off? I tried to no avail when I put the new cats on?
Any help an insight is appreciated

 

Just uploaded a picture of odometer, because most don't believe that I have that many miles on my truck!

 

You could try a little pick to get between the two halves. Some penetrating oil wouldn't hurt as long as you clean the contacts after. And if that doesn't work add a little heat into the mix from a blow drier or heat gun. At worst you'd have top re pin the connector on the truck side of the harness.

 

Most parts stores have a compression tester in their loaner tools.

O2 sensors won't cause a misfire. If they aren't throwing a code they are functioning. New ones wouldn't hurt, but that's not your problem right now.

 

Ok so I do get codes 420 an 430 as well as codes for fuel inlet fault, I'm not a fan of capless fuel fillers!! I wanted to change the sensors when I did the cats, but couldn't get the old ones to disconnect!! So I cleaned them real good and put them back in! But I think they do I need to be changed!
So just scanned the truck again, my codes are 442, 455, 456, 457, 420 an 430, driving 70 on the highway, now when stopped I get the 304 code and 3098, which I believe is because of one bad weld point in the drivers side cat when I replaced them last week!!

 

420 and 430 are cat codes. 442. 455. 456. and 457 are all evap codes.

The 304 is a misfire in #4, which is the one you need to work on first before you trash your new cats.

Yes, you probably should change the O2's, but they are not causing ANY of those codes.

 

But shouldn't the two cat codes go away , since I've replaced both cats, just not the 02 sensors?
And of my misfire on the number 4 cylinder was a compression issue, wouldn't I have a loss of power especially towing? That's why I think it's the only thing o haven't changed is the injectors!!

 

Those cat codes indicate low efficiency, which can be caused by exhaust leaks or the wrong cats for the application. The front O2's control the mixture, the rears simply monitor the cats.

I did tell you how to check the injectors - swap #4 with one of the others.

You do need to fix the evap system, a bad gas filler won't cause all 4 of those codes to set.

Again, with that many miles, I would still do a compression check on all 6 cylinders.

Clear the codes and see which ones come back.