98 explorer limited 4.0 sohc has no 02 data or no voltage

[rschneider32]

I have a 98 Explorer Limited early production model . This 4.0 sohc has no return data from the 02 sensors. They are flat lined. That coupled with -100% fuel trims, long and short. Although it idles and runs ok, it hitches and bucks going up hill at low rpm. I can O\D off on highway or let off throttle to kick down gears and it won't do that. Frustrated any ideas? Thanks this is a great forum and it's supporters are wonderful.

 

[rschneider32]

Anyone know why fuel trims go to full negative?

 

[Dono]

The short term fuel trims are inverse.
That would mean that at full negative the pcm is trying to add a bunch of fuel. Are you able to see what your front 02 sensors are doing with the reader you are using? Any engine codes? I wonder if you have a power issue to your o2 sensors.

 

[XLTrunner]

If you're still wondering how to remove that fuel line bracket, it's held in place by a 3/8" or 10mm bolt (can't remember for sure). Just removed one a few months ago at the salvage yard. It's a p.i.t.a. to reach and you can barely see it. Need a wrench (socket won't fit) to get at it. The splash guard was removed so I could reach up in there from the wheel opening. Probably took me a good 15 mins to remove it what with the short turns of the wrench and it slipping off the head of the bolt so many times.

 

[rschneider32]

Dono, Thanks for the info on the fuel trims. Had me confused I'm using a V-Gate blu tooth scanner. All 02 are flat lined and show 0 volts. First I'll change the fuel filter. I will check for power at the heated side of the 02 at power distribution box. There are no codes I'll look for the troubleshooting post on the 02 signal wires to the ecm to try and verify that signal voltage.

XLTrunner, Thanks for the response. I pulled the fpr at Littleton-U-pull. Although the explorer I pulled from had a different a/c compressor and I could see the bolt. Still was a pita. On my explorer the back off the compressor is sticking back far enough, I cannot see the bolt at all I don't want to disturb the compressor lines if I don't have to because the a/c works.

I will let everyone know what I find out.

 

[rschneider32]

The short term fuel trims are inverse.
That would mean that at full negative the pcm is trying to add a bunch of fuel. Are you able to see what your front 02 sensors are doing with the reader you are using? Any engine codes? I wonder if you have a power issue to your o2 sensors.

If you have any info to help test the 02 voltage, I would appreciate any you can share.

 

[rschneider32]

If you're still wondering how to remove that fuel line bracket, it's held in place by a 3/8" or 10mm bolt (can't remember for sure). Just removed one a few months ago at the salvage yard. It's a p.i.t.a. to reach and you can barely see it. Need a wrench (socket won't fit) to get at it. The splash guard was removed so I could reach up in there from the wheel opening. Probably took me a good 15 mins to remove it what with the short turns of the wrench and it slipping off the head of the bolt so many times.

I posted down below, Before I had coffee. So I thought I should reply here. I have no idea how I going to get it back in.

 

[rschneider32]

Here are the 02 screens shots

 

[rschneider32]

After checking fuel pump,pressure regulator and leak down. All are within specs. I now have this...

 

[rschneider32]

After checking fuel pump,pressure regulator and leak down. All are within specs. I now have this...View attachment 94928

not what I wanted to show. Obd scan showed TID: $41 CID:$11 min 63,744 current 727. strange it changed that fast. The fuel delivery is working fine

 

[rschneider32]

Well this is better