Hello, 96 Explorer has rough idle, I have replaced EGR valve, dpfe

sensor, egr selnoid, the front left and right oxygen sensors, throttle

position sensor, pcv, I have clean and checked throttle body, cleaned

and checked temperture sensor, cleaned and check map sensor,

replaced air filter, cheked voltage at back of pcm (99 to 103).

I had the codes read and now shows 135 and 131, One says high

negitive reading, the other states a wiring issue?

any help?

 

O, I also checked and tested idle air control valve.

 

For the sake of those who search this forum for diagnostic codes, in the future please reference them by their full code number, P0135 and P0131.

Which engine does your '96 have? Have you checked for vacuum leaks?

For the P0131, the possible causes are listed as:
-- Contaminated HO2S (water, fuel, etc.).
-- Crossed HO2S signal/signal return wiring.

For the P0135:
-- Shorts to B+ in harness or HO2S.
-- Water in connectors.
-- Cut or pulled wires.
-- Disconnected wiring.
-- Open VPWR circuit.
-- Open GND circuit.
-- Low battery voltage.
-- Corrosion or poor mating terminals.
-- Damaged HO2S heater.
-- Damaged PCM.

Both point to Bank 1, sensor 1. Have you carefully inspected the connector to the B1S1 O2 and have you checked for continuity from the connector to the PCM as well as from one pin to the other and each pin to ground and power?

From what I see for a 1996 Explorer V6 and V8, pin 99 at the PCM is for fuel injector #6 and pin 103 is power/chassis ground. For both engines you should have been looking at pin 60 (gray/light blue) for the B1S1 O2 sensor signal and pin 91 for the signal return.

-Rod

 

Thank you for getting back to me, yes I have checked the vacuum lines and had checked the wiring harness on both O2 sensors, it has the 4.0 engine. I wasn't sure if I should splice outside of the PCM and add new wire and connectors?

 

To what extent have you checked the wiring harness, just visual or using a continuity tester and the checks I mention in post #3 above?

-Rod

 

I had checked the wiring harness prior to changing the O2 sensors, I had probed the back of the of the connector to check for voltage, Prior to changing the O2 sensors we had never received the above codes.

 

Did you get universal heated O2 sensors that you had to connect the wires to, or heated O2 sensors for your application? Have you tried a scan tool with datastream to confirm the voltages from the sensors as well as the heater current? With the engine off and key on the only significant voltage that you would have at the connector would be the voltage for the heaters. Based on the possible causes for the codes I would again suggest you check the wiring for shorts to ground, power, and Vref as well.

-Rod

 

yes I put in the exact fit sensors,I have tried two different code readers and both are reading the same, I am planning to expose and check the wiring and do a more thorugh job of inspecting the wiring harness, it is tough because of their locations, I will post what I find.

Thank you

 

HOLLY MOLLEY, You can not trust the codes that your PCM gives your code reader ! ! !

as I have noted, I have replaced and test many parts and spent many hours trying to

repair the problem because of the codes I was receiving. It turned out to be a Plenum

leak and the nut from the egr tube rail to the Plenum. I had followed great advice and

the chilitons book. The best way to check for a vacuum leak is with propane, I know

that soappy way is the eaisest and most afforable but not the most accurate. I hope

know one else has to go through this, I do suggest to have an experienced guy do the

propane test. Thank you

 

bump, bump

 

What's with the bump? I understood post #9 to say you found the issue and it was a plenum leak and an issue with the nut from the EGR tube. Are you saying that didn't fix it?

Since you're requesting further feedback, I will add that I've never heard of using soapy water to check for a vacuum leak. That usually works if you're checking for a pressure leak, but I don't see how it would work for a vacuum leak. I have heard of propane and carb and choke cleaner, I've heard of talcum powder, and I've heard of smoke machines, but never soapy water.

-Rod

 

Why can't you trust the codes? Code 135 & 131 tell most of us that you probably had a vacuum leak like shorod said. Anything from the MAF in is under PCM monitored vacuum.

 

shorod, thank you for your input, I am as not adversed in repairs of a Explorer as yourself, i wasn't fimilar with the propane test and was impressed on how accurate it was (or how bad the leak was). I wanted to make sure that other novice Explorer owners are aware of this, sorry that it was an inconvince to you.
SEAL1, we have been getting many different codes and was repairing and testing many other items due to the codes we where receiving, and when we were given po135 and po131 (you must write the full code in this forum, as I was directed to) it pointed to a electric short or bad connectors or something along the circuit not the Plenum, hince my excitment when the true problem was found.

 

Ooops, the struggles with the Internet. I can tell my comments came off as direction rather than guidance with a bit of a superiority complex mixed in. I am sorry, that was not my intent. My intent, as is the intent of most on this forum, is to help where I can and learn where I don't know. Posting the full code number is help since folks who search for "135" in the future will find posts containing "P0135" but those searching for "P0135" will not. Actually, the forum search feature may not allow a search for "135" anyway as being too short....

Also, my experience is folks "bump" their threads because they are still looking for input. I thought you found your issue so I was curious what further input you are seeking. That, and your comments about using propane, were not an inconvenience to me, I just wasn't clear what further help you were looking for on this subject. I'm still not.

Can we start over?

-Rod

 

all is good