It's back! Or something like it. As you may recall, I had a bad computer and swapped it out (along with plugs, wires, filters, etc) over two months ago. The car had been running fine, until today. I drove approx 20 miles to work and car sat in parking lot all day. Came out and started home this evening, and I noticed as soon as I pulled out of the parking lot that the car was missing. It drove, but it was noticably weak under load. I had to pull off road several times to let others by and stop and restart engine. That seemed to help for a short time. I could get up to 50 or so but soon engine would start losing power and speed and I'd have to repeat.

OK, I made it home and pulled codes. Got a 172 and 177 which seem to counter each other. I know the drill, I'll check fuel pressure and the regulator in a couple of days when I have time off. the O2 sensors were changed back in Sep-Oct with Bosch. I've put only about 800 to 1000 miles on it since last problem. Will get back with readings.

 

I'll try to check my code book when I get home tonight. Maybe fuel based on what you're saying. Another thing too is that Ford incorporatd a "limp home" mode into the PCM program. When I experimented with a SCT chip, I flipped it into this mode - closest thing to a disable ignition mode they can do on an EEC-IV. It drove just as you described. I didn't even get to 35 MPH and I was convinced the limp home mode worked. But since I forced this with the chip switch, I simply switched back to normal mode and it was fine. When this happens on it's own, it is in response to some grave engine controls malfuntion(s). Maybe fixing the codes issues will get back to the normal mode, if in fact it's stuck in limp home.

 

Both 02 sensors - right is lean, left is rich. The one time I saw this, the guy had the 2 leads swapped side to side. One got off a little and then overcompensatted each bank too much the wrong way and the O2's stop switching - just like yours are doing.

I remember this post from last summer but not all the details and too late tonight to read all 6 pages.

What all did you do to fix it and is there any chance you could have swapped the O2 leads? Even 2 -3 months ago as it might take that long for one side to get a littl off on A/F mix again in the long term correction factors.

Could trying clearing the computer again and see what happens.

 

It's possible to switch the leads, but I would have had to force it, I think. I believe the auto side connectors are Physically separated enough to discourage crossing them, but I'll look at that closely tomorrow when I have time to TS.
Might even try crossing to see what happens.
Would the sensors be bad, if that's what happened? Can I clean them up and reuse since there is such little operating time on them (2 mts, <1000 miles)?

 

Kind of theoretical but since you have so little miles on them, the resetting of the computer when you installed them could have gotten engine controls to an operable level and now with some miles down, correction factors are inverted - if the leads are swapped. It would be hard as you mention since the left hand lead is a lot shorter but for sure the righ hand lead can make it to the left - at least on my car. I've got mine all torn apart right now and I labled one of the leads to be safe.

You can clean O2's. I've seen a procedure tht involves a tourch and a vice. Basically heating it up to burn off any contaminates. Heavy oil deposits or anti-freeze can kill an O2. You might have one bad one but probably not two since they are failing in opposite ways.

Couple easy things - reset computer and test. If still present, pull plugs to verify codes - should have one bank black and other white. Look at the O2's - is the lean one black with soot? If so, it broke internally and is leaking exhaust to the outside. This throws off the reference signal, shows lean, and the PCM actually richens up that side - happened to me.

 

OK. Understand. I got home a little early and tried a couple of things without getting too involved. First, I test drove to see if problem was still there....it was. Then reset computer by disconnecting battery cable. Reconnected and tried with similar results. Pulled codes and system test passed.....no codes.
Will pull plugs tomorrow and see what they say.

 

Today's status:

I pulled plugs on both sides and they looked clean, no carbon like before.
Reset codes and ran engine until it started acting up. Ran engine off test and got no codes. Ran engine running test and got 137, sensor fault, always rich.
I ran test a few times as when engine would start running rough, it created a couple of other faults, I believe unrelated, as engine would stall. When engine did not stall too badly, but ran rough, the 137 was all that was generated.
I checked fuel pressure and all was normal, 40 engine off, 31 at idle and no indications of pressure causing engine actions.
I pulled both o2s and they looked clean and normal. I closely looked at wiring connections and believe they are hooked up to the correct connectors and not crossed.
Can you isolate one o2 from the other to see which is generating the fault?

 

This is a Fed car right, not Ca?

 

Right, it's a Fed car. The weather is getting a little cold and windy to do too much more, but I'm thinking I need to pull all the plugs to see if there might be a cylinder acting up.

 

Looks like bank 1, which I'm pretty sure is the passenger side, has a gray/lt blue wire to the PCM and the bank 2 has a red/black wire to the PCM. First make sure these are OK. I looked at my car last night and you could swap the leads - they are long enough.

If that's OK, then you can switch the 2 sensors side to side and see if the 137 (left rich) geos to the right side as rich. If so, the sensor is bad since nothing else changed. If the plugs are white but the sensor says rich, the PCM is not giving enough gas - white plugs prove this. I'm leaning towards a bad sensor. Now that you have just one side showing bad, we need to look at what can affect just one side - O2, plugs, wires, valves... Make sense?

 

Yes, I thought you did pull all the plugs. You could have a single cylinder that is doing something wierd so they all have to be looked at.

 

My book doesn't show that a 137 code is a left rich fault. Is that what you show? If so, makes sense to swap.

 

I braved the wind and cold and pulled the rest of the plugs. All normal burn.

Traced the wires to o2s. The red/black(seems to be the key difference from one side to other) wire goes to sensor on the right side (passenger side). My book only calls it sensor #2, it doesn't say left or right, so I don't know which one is which.

 

Comment on #85. Looking at my wiring harness, the cable to the o2s run on the right side of the engine, then split with a short cable and a longer one going to the sensors. I would think the shorter cable would go the the right side since it's already on that side and the longer one goes to the left, as it has to cross over to the right. The shorter cable has the red/black wire, so think that's the correct configuration. Right?

 

Sorry DBLEE - I've been in the garage all day getting my trans back in the Ex.

I know what you mean about the length of the cables on the O2's. I was looking at that today before I benchpressed the trany back into position with one hand and started the bolts with the other.

I had previously tie wraped the right hand side cable with a loop since it was so long. The passenger side is the long one, not the driver's side. But did you verify the wire colors? What I posted before was off the autozone web page diagram.

PCM codes - I have a printout from somewhere, just looked and 137 and 177 are the same descriptions - redundant - left rich and not switching. It also said same here at www.fordfuelinjection.com

Sounds like you might have your O2 leads wrong. Any other codes but 137?