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02 Explorer 4.6 low on power?

coletrain777

Member
Joined
October 9, 2010
Messages
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City, State
Harrisburg, MO
Year, Model & Trim Level
2004 Mountaineer Premiere
So I picked up a 2002 Explorer limited a while back and it had a miss at idle and was low on power (like it wasn't getting enough fuel). I put in new plugs and put all new coils on (all old coils ohm'd OK, but a few missed under load). Well... the miss is gone from the engine at all rpms, but it still is lacking power like either the cats are plugged or it's not getting enough fuel. I have replaced the fuel filter, but have not tested fuel pressure. The vehicle starts great, idles well, and is not throwing any codes. I am not exactly sure where to go from here, here's a few questions...

1. What is the best way to ensure that I don't have a catalytic converter issue. Is there anything I can do to test it 100% short of cutting out the cats to test?

2. Previously I did get it to register a code p1309 which is a "Misfire Monitor Disabled" code. From what I can find this code is usually fixed by replacing the CPS. I had another known good CPS that I swapped in and my engine still exhibits the same low power issues. Any other ideas what could have caused this code, my friend that is a tech at the local Ford dealership says he is clueless as to a definitive fix for this code.

3. The transmission shift points under heavy acceleration are poor. It doesn't want to shift from 2nd to 3rd under full throttle unless I let off of the gas a moderate amount. If I keep the pedal to the floor it seems to hang at high rpm and not accelerate until I let off to let it shift into 3rd. Not sure if this problem is related...?

4. Are there any other tests that I can run to help pinpoint the issue? I am a fairly competent mechanic but this one has me stumped. The vehicle runs great if I just drive around normally, but if I tow a medium sized load with it you can tell that it is low on power and something is not right.

Thanks in advance for the help, I sure appreciate it!

PS... For those of you wondering I have not given up on the 5.4 swap into my 04 Mountaineer... the engine and trans are all together just waiting to be dropped in, I just have been so busy working on other people's cars (and buying/selling vehicles) that I haven't gotten around to it... One day I hope :)
 



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Not sure if you have emissions testing where you're at, but I had the same issue happening with my 4.6. I dropped my y-pipe and hollowed out my cats. It runs great now. Doesn't throw any O2 codes either.
 






Brian - This morning at about 6am I went out and tapped on the front two cats and the rear one... lo and behold the rear cat has lots of loose guts rattling around in it. I proceeded to slice it open and empty it. I came back in and saw your post and it gave me hope that I had found the problem so I went for a test drive with the boat in tow... It seems like this was my problem, its seems to have normal power back! Glad to hear that you didn't have 02 codes pop up after gutting the front cats, that means that it's a pretty safe bet I wont get codes from just gutting the rear cat.
 






Well there aren't any downstream O2 sensors after the third cat so you won't throw a code. I'm running 30 pound injectors and ported heads on my 4.6 so if I'm not throwing codes then there's no way in hell you will :D

Also, the third one isn't actually a catalytic converter. It's more of a resonator. From what I understand it doesn't have the same insides so your cats may still be bad.
 






Brian - Thanks. The third cat that I gutted is most definitely a cat, full of the factory honeycomb platinum material that I've found inside ay other cat I have torn into. When I get back from vacation I just may drop the y-pipe and clean the front two out to ensure to plugged problems.
 






Brian - Thanks. The third cat that I gutted is most definitely a cat, full of the factory honeycomb platinum material that I've found inside ay other cat I have torn into. When I get back from vacation I just may drop the y-pipe and clean the front two out to ensure to plugged problems.

Oh okay. When I had mine removed I didn't look at it. There will be an electronic cutout going in its place :D
 






i have a 2004 for explorer runs smmoth at idle but will not reach full rpm
 






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