Dear, Forum.
My 96 4.0 has had a bad time passing DEQ (Department of Environmental Quality) here in Or. Keep getting not ready codes for o2, o2 heater and cat. sensor.

Disconnected the battery to work on fuel evap. solenoid. Sense then will not pass smog test, Any Ideas?N

 

since yours is a 96 OBDII system, you'll need to buy an OBDII code reader or most auto parts stores will read for free, call ahead.

please write down the code numbers and post to the forum so we can help you

what type of service work has been done in the past 6 months?

 

Thanks for responding 96_4wdr,

Yes I have and have used the OBDII reader and it pulls up no codes.
Before I changed the evap. solenoid it pulled a p1443 code so I pulled the bat. neg cable and changed the part and the code went away. Went to DEQ and they pulled the "Not Ready Codes". The employee asked if I disconnected the bat. lately ,said yes , he said put 80 miles on newly connected bat. and all Not Ready Codes should go away. Did it ,not ready codes still there at next test.

 

Usually, for an OBDII system, disconnecting the battery will give you that problem. The "Ready Code" will be set to "False." With that said, if you drive for 80 miles freeway and city driving combined, that should have been set to "True." Keep driving the van at both city and freeway conditions for a week or two and it should be set.

Actually, a good OBDII reader should be able to tell you the "True-False" condition of this flag..

Well, that's about the end of what I know on the subject. Good luck and I hope it works out for you.

 

Everything and more than one wants to know about FoMoCo OBDII system op.
http://www.motorcraftservice.com/vdi...f/obdsm963.pdf

I/M Readiness Code
The readiness function is implemented based on the J1979 format. A battery disconnection or clearing codes
using a scan tool results in the various I/M readiness bits being set to a “not-ready” condition. As each noncontinuous
monitor completes a full diagnostic check, the I/M readiness bit associated with that monitor is set to a
“ready” condition. This may take one or two driving cycles based on whether malfunctions are detected or not.
The readiness bits for comprehensive component monitoring, misfire and fuel system monitoring are considered
complete once all the non-continuous monitors have been evaluated.

On Board Diagnostic Executive
The On-Board Diagnostic (OBD) Executive is a portion of the PCM strategy that manages the sequencing
and execution of all diagnostic tests. It is the "traffic cop" of the diagnostic system. Each test/monitor can be
viewed as an individual task, which may or may not be able to run concurrently with other tasks. The
Diagnostic Executive enables/disables OBD monitors in order to accomplish the following:
• Sequence the OBD monitors such that when a test runs, each input that it relies upon has already
been tested.
• Controls and co-ordinates the execution of the individual OBD system monitors: Catalyst, Misfire,
EGR, O2, Fuel, AIR, EVAP and, Comprehensive Component Monitor (CCM).
• Stores freeze frame and "similar condition" data
• Manages storage and erasure of Diagnostic Trouble Codes as well as MIL illumination
• Controls and co-ordinates the execution of the On-Demand tests: Key On Engine Off (KOEO), Key
On Engine Running (KOER), and the Output Test Mode (OTM).
• Performs transitions between various states of the diagnostic and powertrain control system to
minimize the effects on vehicle operation.
• Interfaces with the diagnostic test tools to provide diagnostic information (I/M readiness, various J1979 test
modes) and responds to special diagnostic requests (J1979 Mode 08 and 09).
The diagnostic also executive controls several overall, global OBD entry conditions.
• The Diagnostic Executive waits for 4 seconds after the PCM is powered before initiating any OBD
monitoring.
• The Diagnostic Executive suspends OBD monitoring when battery voltage falls below 11.0 volts.


your system is telling you that the Dia. Ex power up test is not passing the O2 system. failed O2 or wiring/connector. sounds like burned out heater in front O2 sensor. rear O2 back of CAT has nothing to do with fuel system management but is only a CAT efficiency monitor. some states will not pass a veh. now with the rear O2 failed.

did you have the same problem prior to working on the fuel vap. ev. sys.?

a failed wide open fuel vap. ev. valve can dump too much fuel vapor into system and burn out a CAT or O2 sensor.

 

Check all the evap lines are connected properly. Do you have the tailpipe readings? What did it fail on? high HC is generally unburned fuel (could be Evap purge system, leaky injectors or misfire)......high NOx= high combustion temps; (could be EGR, lean A/F ratio)..... & high CO generally caused by rich A/F ratio (could be ECT , sticky thermostat, etc).
If you look up the individual test conditions, it states what sensors are needed for which particular test. If any of the sensors or circuits are faulty for that test, it will not complete. I remember I had a CEL on for CMP sensor circuit failure & this prevented 3 monitors from being completed. When I repaired the CMP, all the three monitors completed within a 15 minute drive cycle. You can find out the drive cycle conditions under which the test should complete. Basically you need to do brisk acceleration ,steady highway cruise for about 2 minutes some stop start driving & engine up to temp for about 10 mins. It will also relearn the idle control etc at the same time, while parked at a stop light etc.

 

Ok, first of, replace all the O2 sensors if they haven't been replaced in the last 80,000 miles. Secondly, after the codes are cleared, the vehicle need to complete at least two drive cycles, with a drive cycle being defined as a cold startup, the reaching warmup, driving at a variety of speeds including highway speeds. A second drive cycle must the be the same as the first. Also in order to complete the readiness tests, the check engine light must be working, if the bulb is burned out the vehicle will not pass the readiness test.

Since you failed on both O2 sensors, I would say, just replace them. O2 sensors don't set codes unless they have absolutely, positively, beyond any doubt failed.

 

Thanks you guys for all your help and time. Im going out to replace all cat. and o2 sensors today. By the way is there a list of FTE tech acronyms ?

 

Write the them up & we will fill in the blanks.
Good luck. Aeroman.