Input GREATLY Appreciated...

[Daniel Ogden]

Hello everyone. I am hoping somebody here has had some experience (hopefully a better one than I am having) with this issue and can give me some advice. I have a 97 Explorer 4.0 OHV that I have been trying to fix for a while. I have been getting rich codes on both banks as well as lean codes intermittently, although both banks always show the same condition (lean / rich). The car idles poorly and struggles in high RPMs (3800+). I have replaced the following within the last 3 months;
MAF
O2 Sensors
Ignition Coil
Plugs and Wires
Air Filter
Fuel Filter

As I was trying to track this down I borrowed a friends OBDII scanner that also gives real time readouts from the O2 sensors. The thing is that none of my 3 O2 sensors were sending any signal (or if they were the scanner didn't read it but I doubt that is the case as it was giving me a lot of other information). I used a multimeter to make sure that they were all getting power and they are. I am pretty sure that the solution to my problem lies in the O2 sensors but I have reached the extent of my technical knowledge. ANY direction would be appreciated. I did have a power wire ground out on my car for about 3 seconds a few months back and it melted a wire which I replaced and everything else works great. Thanks in advance.

 

[Tbars4]

...If you bring us the exact codes you pulled we can better help you...

...Just a guess but probably P0171-P0174...What other codes???

 

[Daniel Ogden]

I'm not sure what the exact code numbers are as I've just cleared them but they were bank 1 too lean, bank 2 too lean, bank 1 too rich bank 2 too rich. And again the two banks always throw the same code at the same time. I will try and go pull them again and post them if I can get my hands on a scanner again.

 

[Jacksonkm630]

Sometimes when both banks are throwing "too lean" or "too rich" codes, the Upper and Lower intake manifold gaskets could be leaking.

I was getting the too lean code in both banks on my 2000 4.0 OHV. Replacing the upper gaskets (beneath the intake plenum) and the lower (beneath the fuel rail) corrected my problem.

There is a thread showing how to replace these gaskets....I'll try to post for you.

http://www.explorerforum.com/forums/showthread.php?p=1555157

 

[Daniel Ogden]

I replaced the head gaskets when I bought it (got it for $600) and took great care to make sure all the gaskets were seated properly I also replaced them all. I definitely could have screwed up but the fact that the O2 sensors aren't sending any info seems to be the problem to me. The problem is I have NO clue what to do about it. How would I go about checking for leaks though? I would like to rule that out as well. Thanks again.

 

[jlsparky7]

One way to check for leaks is to spray comes thing like carb cleaner or starting fluid in light spurs around the manifold to see if the engine revs up at all.

Could be your computer or a bad ground causing all the problems as well.