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4.0 swap complications(codes after install)

chrwilkins30

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Been working on this thing for 9 months and the last 5 have been a big pain the the ass. I got a 88 bronco 2 with a 94 explorer 4.0 that I swapped out.using the complete explorer harness. I drove the explorer home 70miles, and it ran great.sounded like a prius. I am getting a rich condition very badly.

Getting this code.
136 R Heated oxygen sensor indicates lean condition, left side


Did a cylinder comparison test (not correct term)on reader and got 40,50,60 which means that that side has a problem.

Remember, I drove this home and it ran perfectly fine. Its running so rich that it burns my eyes. Need this before winter, any ideas??

Has fuel pressure, FPR testes out fine. Brand new o2's, wires and wires.

as much as I dont want to I'm about to take it somewhere.what in the hell do I test next.
 


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Low voltage from the sensor indicates a lean condition. The computer sees the lean conditon, inferred by the low return voltage, and is adding fuel to try and compensate.

If the signal return or O2 ground wires got pinched or damaged during install it could do that.

It's also possible that the sensor is bad. To quote something I saw in the BII section, "a new part is an untested part, not a good part".

I would start by swapping the sensors side to side. Since the other bank isn't throwing that code you can assume that one is good. If the problem follows the sensor, you know it is bad. If it stays on that side I would start looking at the wiring.

Also, what is the correct term for your "cylinder comparison test"? Knowing what those numbers are could help.
 

chrwilkins30

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I have switched side to side the original and after replacing both it always stayed on that side.
 

chrwilkins30

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Driver Side

<embed width="600" height="361" type="application/x-shockwave-flash" allowFullscreen="true" allowNetworking="all" wmode="transparent" src="http://static.photobucket.com/player.swf" flashvars="file=http%3A%2F%2Fvid1090.photobucket.com%2Falbums%2Fi366%2Fchrwilkins30%2F20131017_164501_zpsbe0081b6.mp4">

Passenger Side

<embed width="600" height="361" type="application/x-shockwave-flash" allowFullscreen="true" allowNetworking="all" wmode="transparent" src="http://static.photobucket.com/player.swf" flashvars="file=http%3A%2F%2Fvid1090.photobucket.com%2Falbums%2Fi366%2Fchrwilkins30%2F20131017_164617_zpscdd77c7e.mp4">
 

RonD

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Videos don't work/connect, just FYI.

I would think the '94 4.0l would have heated O2 sensors so 15amp fuse required for that, did the '88 also have heated O2 sensors?

You can check for 12v and ground at sensor, read here:
http://oldfuelinjection.com/?p=31

A leak in the exhaust manifold to head gasket can cause O2 on that side to read lean, as can a leak at the O2 sensor, too much oxygen is too lean.
The 136 code also means computer has adjusted fuel trim mix as rich as it can and is still getting lean report from that O2 sensor
 
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chrwilkins30

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Okay. Well the paseenger side would go between .05v to .90 and the driver side would only adjust between .20 to .30.
 

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I would think the '94 4.0l would have heated O2 sensors so 15amp fuse required for that, did the '88 also have heated O2 sensors?
88 had a 3-wire HO2

94 had a 4-wire HO2.

High resistance in the circuit can still cause that. Time to start poking at wires with the volt meter.
 

RonD

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Yes, .2-1.0v is the range, .2 being very lean, 1.0 being very rich.

Just wondering if the wiring change allowed for the different O2 sensors, could be a missing wire connection if the '94 is a 4 wire, but wouldn't account for the other side having good voltage levels
 
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chrwilkins30

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I didnt have to wire o2 sensors at all. The entire bronco is running the explorer wiring harness front to back.
 

chrwilkins30

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Just curious but are the o2s wire ran right to the computer or are they connected to other parts of the system. Because if they are not,ill just run new wires.
 

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Google: autozone 1994 Ford explorer electric

First link should be the "repair guides" for autozone, click on it

Scroll down to
Fig. 29: 1994 Explorer 4.0L engine wiring

Enlarge diagram
In the middle just above the "long bar" that is the EEC/PCM you will see OS sensor #2 and #1, the data(low voltage) comes in on pins 43 and 44
 

chrwilkins30

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Thanks man. I've got the complete schematics for the ex but thanks for the link. Just away from it currently.
 

chrwilkins30

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So I checked the resistance on the o2 at the computer.

For o2 #2, I was getting about 150 ohms for the most part.. This is the one with the lean condition

For o2 #1 it was jumping all over the place.

Is it a resistance problem ADSM?

just tested the o2's and both past a bench test no problem.

Also I got the same voltage at the o2 as I did right at the computer. Would this indicate that I do not have a problem with the wiring?

Need some input in the direction to take.
 
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SenorNoob

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Did you check the resistance there with the truck still warm or running? Or was it cold?
 

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