I think I will try this first. Then, if I still pull a code 42 after it is moved, I'll try adding a heated circuit as 85lebaront2 suggests.

Hey, I don't mean to take you away from your vacation, so don't feel obligated to keep responding. Thanks though, for your help!

 

Moving it back to the original location is a good plan.

You will get better gas mileage with a code 42 -vs- a code 41........

I would still try a factory O2 sensor.

If you decide to upgrade your your O2, go for a 4 wire heated sensor, but the output rating must be 0.0 to 1.0 volts dc.

Not really on vacation, just the second half of my life year, just as much work and fun here. But only limited access to the internet, no worries...

 

Thanks, Vinny! If I were to get a 4 wire sensor, where would the other three wires attach?

Found this: The Wiring is normally one of these colors. Make sure you only pick colors from one column. Things are much easier if you cut as much of the harness out of the junk car as you can to give you as much lead wire as possible. If not at least get the connector and a few inches of wire to splice into your existing harness. The connections should be pretty easy. The sensor ground should run by itself to a chassis ground and not just grounded to the engine in case the engine has a bad ground. The sensor output goes to the factory Oxygen sensor wire. The heater wires do not have a polarity so one wire should go to ground but not using the same wire as the sensor ground. The other wire should go to the ignition and only have power when the key is in the on position and not when the key is on accessory.

The advantage wit the new sensor is that the computer knows when the sensor is working and will use it to adjust the A/F ratio. The old sensor would cool off at idle and while coasting and take a few seconds to get back up to temperature. This left times when the computer could not adjust the A/F ratio. The new sensor has a heater so it will stay working at idle and as soon as you give it gas from coasting. It also heats up much quicker so it starts working much sooner when starting the car. The most obvious thing you will notice the idle is smoother and it doesn’t hesitate as much when going from coasting to accelerating. Overall this is a very simple and cheap mod so if you have some free time I would do it if your car has a 1 or 3 wire sensor in it now.
[QUOTE=vjsimone;16496178]Moving it back to the original location is a good plan.

If you decide to upgrade your your O2, go for a 4 wire heated sensor, but the output rating must be 0.0 to 1.0 volts dc.

 

Now if someone wants it, I have it listed for sale.

On the O2 sensor wiring, I will get a picture of an old one. I did the same on my TurboII K-car setup, the TI engines had a single wire, right in the exhaust elbow, later 3 wire and finally 4. The reason they changed, and most others, a little resistance in ground circuit on a 3 wire would throw the output high.

 

Ok, pictures as promised:




White wires for heater







Gray for signal, black for ground

On the later trucks, it is fed by the back up light feed, purple and orange wire until the OBD-II systems, then the 3 O2 sensors are fed directly from the PCM power relay, but are sensed (maybe regulated) in the PCM so a bad heater will set a code.

 

Just kidding, but it's funny.....

 

Update - I purchased a 4 wire O2 sensor. It's a type 2 sensor meaning it's got 2 white wires, one grey and one black. One white wire goes to ground, the other to a fuse (radio) for the heating element. The grey wire also goes to ground, but to a different location than the white ground wire. The black wire goes to the O2 sensor wire connected to the ECM. It was my hope that by having a heated O2 sensor, my idle wouldn't fluctuate while stopped at a traffic light from 520 rpm's to around 490; after about 30 seconds stopped at a light, the idle would suddenly drop/stumble, to 490 and after another 20 seconds or so, it would jump back up to 520. It seemed to me the O2 sensor was "cooling" and the ECM was changing the fuel/air mixture. I was also pulling a code 42.

After changing the O2 sensor from a single wire to a 4 wire unit, I noticed my idle was holding more steady at 520. Although there is still an occasional drop in rpm's while at a stop, the drop is infrequent and recovery is quicker. However, I'm still pulling the code 42. I can live with that, I suppose. I might still move the sensor to a different location, possibly farther down the exhaust to incorporate both exhausts. But I suspect that may be a crap-shoot and more trouble than it's worth. I've heard that O2 sensor location is really important and moving too far away from the engine could be detrimental. Not sure about the reliability of the later information as that individual (from Advanced Auto) has given me bad intel before.

How does she run? Overall, fabulous! If it weren't for the occasional drop in rpm's at a stop, I'd say she runs perfectly.

Thanks to all here for the tremendous help on this forum and a special thanks to Vinny. I've learned a tremendous amount and believe I now know my truck and it's workings really well!

 

Ok, one little item, on the bank fired truck engines, the injectors are grouped in sets of 4, 1,4,5,8 and 2,3,5,6 or end 4, center 4. Therefore a single O2 sensor "sees" both injector banks. The EEC takes these readings and adjusts the mixture. One bad injector on the right bank of that system can drive it crazy.

I am not going all the way back, but were you able to get a solid 1.0 +/- .05 Volt reading on your TPS? The 1985.5 and 1986 systems are very sensitive to this as the EGR control system is completely different from the newer trucks. EGR vacuum solenoid opens at roughly 1.1 V TPS signal, then the EEC tries to regulate it by bleeding air through the EGR vent solenoid and closing the vacuum one. If they are "chattering" when the idle is surging that is your problem. We chased a similar issue on my son's 1986 F-150.

 

Hi 85lebaron2 -

I'm not recalling what my volt reading was on the TPS. Lesson learned - I will start writing those things down. It'd be quicker for me to just check it again, rather than try to find in this massive amount of posts, and I will do so. If the voltage is greater than what you specify, or less, how do I regulate it?

With regard to solenoid chatter, when my idle was set too high, I experienced that chatter in the bank of solenoids that the vacuum hoses feed. No chatter exists there now as I have adjusted my idle screw to where it belongs by following a process outlined for me by Vinny.

All injectors are new. However, how do I check to see if I have a bad injector?

There's still much to learn.

 

If your injectors are new, there shouldn't be a problem. Best way to see problems is to look at the plugs. BTW, do not try Bosch platinum plugs in a Ford.

 

Plugs are champions and are not fouled. Thanks, though, for the warning.

 

Did your fuel pump running issue / truck not start ever reoccur?

 

Not since I replaced the ECM.

 

ok. That's what I feared.

 

Gary, did Subford have anymore ECA/ECM schematics to offer? Thanks