Help! P0172 (I changed the 02 sensors too)

[gary762]

I have a '99 Ranger 2.5L with 92K miles.
For the last several months I have been getting the code P0172. I have a reader and a device that lets me whatch the 02 sensors working. I have done several things that stop the code from popping up but only temporary. Maybe a couple weeks and then it comes back up. There is no smoke or anything. The truck starts right up and gets about 23 MPG. I've made no chip mods.

I have recently:
Changed the oil, oil filter, fuel filter, air filter.
New plugs (autolite irridium). I used anti-seize compound.
New plug wires.
cleaned air intake sensor

Some mods I've made in years past that have not affected this issue:
ACCEL EDIS coils
ACCEL fuel injectors
Gibson cat-back exhaust

The only thing I can think of is maybe the CAT is going bad?
What can I check?

 

[Bryan22]

you said you cleaned the air intake sensor. is that the MAF or the IAT you cleaned? if you didn't clean the MAF clean it. that's where i'd start. and check for exhaust leaks before the o2 sensor.

 

[gary762]

you said you cleaned the air intake sensor. is that the MAF or the IAT you cleaned? if you didn't clean the MAF clean it. that's where i'd start. and check for exhaust leaks before the o2 sensor.

I cleaned the MAF several times over the last few months.
I'll look for exhaust leaks. There's one 02 sensor before and one after the CAT.

I'll let you know.

 

[gary762]

The catback exhaust came loose. Problem should be fixed now.

 

[disciplerocks]

That shouldn't cause it to run rich. Its definitely not the cat though. Its a bank 1 code which is the first O2 sensor before the cat.

I want to know if your accel injectors are higher flow than stock and if so is the maf calibrated for them?

 

[gary762]

That shouldn't cause it to run rich. Its definitely not the cat though. Its a bank 1 code which is the first O2 sensor before the cat.

I want to know if your accel injectors are higher flow than stock and if so is the maf calibrated for them?

Good Point... About 5 years ago I got the accel injectors. I don't remember the rating units, but it was just one more than stock (19 I believe).
After installing them I disconected the battery overnight to reset everything.
It's been running fine for years until now. The MAF has not been changed. I figured the OBD would reset accordingly since it was such a small change on the injectors.

 

[Bryan22]

any luck?

 

[gary762]

any luck?

No luck, tightened the bolts but code came back the next day.

 

[modelageek]

whe you cleaned the maf did you do it when it was cold? did you touch teh wire with anything but the maf spray. did you let it dry before putting it back in. if this was my truck this is what i would do. Put a bottle of techron in the tank. suspect the maf. Do a fuel pressure test. koeo and koer...........any air filter mods?