Monitors not completing test

[wsrzerotwo]

ok, first off hello im new here and have found many helpful threads here and i hope you guys can help me with my specific problem..

so heres what i have:

96 ranger 2.3l (8 plug) 5 speed regular cab

i bought it off a friend of mine with a blown head gasket last year with 112k miles. here is what i did initially when i did the head:

fresh head with valve job
head gasket
plugs
wires
ignition coils
egr valve
evap solenoid
dfpe sensor
iac valve
tps
pcv valve
water pump
thermostat
ect

i basically did a pretty major tune up and tried to replace everything i though could and would wear out. it ran pretty good at first but i seemed to have the dreaded hesitation/stumbling problem that ive read so much about here.


a few months ago i noticed a crack in my cat and i had a smog coming up so i replaced that.

ive replaces most of the vac hoses and did a propane test to check for intake leaks and found none. it didnt really bother me at this point i pretty much got used to it, the truck never stalled and had good on throttle response. now it comes time to get it smoged in good ol california. i have a scan tool and could see that not all monitors were showing completed, but only four werent so i gave it a shot and passed with flying colors except failed because not all monitors had run.

so i got an extension and have been driving now for about a month and the monitors refuse to run. i have also tried to drive evenly and do some of the procedures to get the monitors to run (such as letting it warm up, drive up to 45 for 10 min, coast to a stop.... etc etc) and the monitors STILL refuse to run. i have put probably 500 miles in this manner, still no monitors. there have been no DTC codes whatsoever, however it seems to stumble still but idles around 6-700 rpm.

here are the monitors that will not run:
catalyst monitor
oxygen sensor monitor
oxygen sensor heater monitor
EGR monitor

this would seem to indicate the o2 sensors to me, but i dont want to just start replacing parts, especially because there have been no problem codes.

what do you think? any help/advice/experience you can share is much appreciated.

i only have a month left when i have to smog the truck (stupid cali will only give you one extension now) so i need to get this figured out pronto

 

[jremington59]

Are you re kicking the check engine light for anything?

If not, try doing this.

I know this is an old thread, but here's the drive cycle you use to quick cycle the computer for inspection.

NYS DMV - (Brochure) DRIVE NY CLEAN
1. The OBDII drive cycle begins with a cold start (coolant temperature below 122
degrees F and the coolant and air temperature sensors within 11 degrees of
each other).
2. The ignition key must not be left on prior to the cold start - otherwise the heated
oxygen sensor diagnostic may not run.
3. As soon as the engine starts, idle the engine in drive for two and one-half
minutes, with the air conditioning (A/C) and rear defrost turned on, if
equipped.
4. Turn the A/C and rear defrost off, and accelerate to 55 mph under
moderate, constant acceleration. Hold at a steady speed of 55 mph for
three minutes.
5. Decelerate (coast down) to 20 mph without braking (or depressing the
clutch for manual transmissions).
6. Accelerate again back to 55 to 60 mph.
7. Hold at a steady speed of 55 to 60 mph for five minutes. Decelerate
(coast down) to a stop without braking.

If you're unable to do all of these steps, doing steps 1 through 5 from a cold start will accomplish the same thing.

Try this cycle twice.

 

[wsrzerotwo]

i did clear the dtc a couple of months ago when i replaced the aic valve and was getting a p1506 code

 

[thumper477]

I would try a different PCM.If you have no codes for that long a period of time there is no reason that all your monitor should'nt set.You may have a bad computer.

 

[wsrzerotwo]

is there any way to actually confirm that i have a bad PCM? the weird thing is i had it smogged after i bought it and replaced the head and it passed. that was probably about a year ago, is is possible for my PCM to just start malfunctioning like that?

 

[jremington59]

Do you have a check engine light on right now? If not, the problem isn't with the O2 sensors or the other banks that won't cycle.

 

[wsrzerotwo]

no there is no check engine light on which is strange, because if the o2 sensors were out of range it would pop a code i would think. its sounding more and more like the pcm. any advice on finding an inexpensive replacement? should i try a "hard restart" on the computer? (unplug for a while and disconnect battery?)

 

[jremington59]

If you unhook the terminals it will clear all the banks. If you still have a month it won't hurt anything to give it a try. It should only take a couple days of light driving, or do the cycle I posted to load them.

 

[wsrzerotwo]

it looks like i may be looking for a computer. i reset the computer and put about 200 miles on it already, with no activity on the monitors. im going to give it a couple of weeks but i want to be prepared if i need to get a computer so here are a few questions:

does the 8 plug use a different PCM than the 4 plug?

is there a specific part number i should be looking for?

will any ranger 2.3l OBDII computer work?


thanks for your help in advance..

 

[wsrzerotwo]

bump... common guys i know somebody has dealt with this before

 

[thumper477]

Pull out your PCM and write down the numbers off the ford label.Go to your local big junkyard and match one up.An alternative is to look on Ebay.I have bought many used computers off the bay in the last 10 years with good success.All the numbers off the label should match to have the best chance of getting the right operating system for your particular application.

 

[XLRVIII]

curious thought from the far side/peanut gallery.

I've seen something similar to this...

turned out the PCM had been flashed and they did a bunch of stupid stuff in the emissions area of the tune... by disabling those functions, they cause most if not all the emissions monitors to "not complete".

 

[wsrzerotwo]

I seriously doubt that there was ever a flash tune done on the truck. I'm the second owner and the first had no intention of performance tuning. One thought I had was I read somewhere that its bad to clear the DTC codes while the engine is running. I have done this several times, could this have damaged my ECU? As I mentioned before I smogged it a little over a year ago, could the ECU just start malfunctioning?