2005 4.0 failed State Emissions Inspection today (I have the codes)

[Mjdtexan]

Well, the ole Explorer failed inspection today. I knew it might. The check engine light stays lit, however it went off on its own today so we figured we would run her in and give it a go. It still failed.

I have noticed that it runs rough when first started, then it settles into a nice little idle after its warm up.

Here are the codes:

1. P0430 Catalyst System Efficiency Below Threshold (bank 2) I do not know
what ths means

2. P0401 Exhaust Gas Recirculation Flow Insufficient Detected. I do not know
what this means

3. P0316 Engine Misfire Detected on Startup (first 1000 revolutions) I do not
what this means

4. P0304 Cylinder 4 Misfire Detected. I think this may be that particular coil
pack (I replaced all plugs and wires 3 months ago)

5. P0128 Coolant Thermostat (Coolant Temp Below Thermostat Regulating
Temp) I expect this just means to replace the thermostat?



Every thing not in bold print is exactly like it reads on my failure slip. I can remove and replace parts all day long with confidence but I admit to not knowing the technical stuff that one needs to know when diagnosing this kinda stuff. I would appreciate any help that I can get. I need to put a sticker on this truck. I know where I can go and have her "pass" inspection but I would rather treat this particular on the up and up.

Thank You in advance

 

[esclamada]

Well, the ole Explorer failed inspection today. I knew it might. The check engine light stays lit, however it went off on its own today so we figured we would run her in and give it a go. It still failed.

I have noticed that it runs rough when first started, then it settles into a nice little idle after its warm up.

Here are the codes:

1. P0430 Catalyst System Efficiency Below Threshold (bank 2) I do not know
what ths means

2. P0401 Exhaust Gas Recirculation Flow Insufficient Detected. I do not know
what this means

3. P0316 Engine Misfire Detected on Startup (first 1000 revolutions) I do not
what this means

4. P0304 Cylinder 4 Misfire Detected. I think this may be that particular coil
pack (I replaced all plugs and wires 3 months ago)

5. P0128 Coolant Thermostat (Coolant Temp Below Thermostat Regulating
Temp) I expect this just means to replace the thermostat?



Every thing not in bold print is exactly like it reads on my failure slip. I can remove and replace parts all day long with confidence but I admit to not knowing the technical stuff that one needs to know when diagnosing this kinda stuff. I would appreciate any help that I can get. I need to put a sticker on this truck. I know where I can go and have her "pass" inspection but I would rather treat this particular on the up and up.

Thank You in advance

start with PO316 - bad connection to the injector, either a loose or bad injector connection (6th injector). This means the injector is not working.

P0304 - bad plug and/or COP, replace both (plug is cheap anyway) or to make sure do the swap test first.

P0128 - could be an open thermostat (replace) or ECT sensor. Thermostat is cheap anyway. Does your coolant temperature go down when driving on the highway? if yes then the thermostat is open.

P0401 - common issue, replace the EGR sensor.


P0430 - if you've been running this truck with those codes on (check engine light) for a long time then your catalytic converter is toast. This is a very expensive replacement. Sometimes the downstream oxygen sensor fails or just a result of those codes. So this is the last code you have to deal with. Do them one at a time since sometimes fixing one code could make the other codes go away (such as the P0430)


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[Mjdtexan]

start with PO316 - bad connection to the injector, either a loose or bad injector connection (6th injector). This means the injector is not working.

P0304 - bad plug and/or COP, replace both (plug is cheap anyway) or to make sure do the swap test first.

P0128 - could be an open thermostat (replace) or ECT sensor. Thermostat is cheap anyway. Does your coolant temperature go down when driving on the highway? if yes then the thermostat is open.

P0401 - common issue, replace the EGR sensor.


P0430 - if you've been running this truck with those codes on (check engine light) for a long time then your catalytic converter is toast. This is a very expensive replacement. Sometimes the downstream oxygen sensor fails or just a result of those codes. So this is the last code you have to deal with. Do them one at a time since sometimes fixing one code could make the other codes go away (such as the P0430)

Thank You very much for that. I believe I can work with that. I will make these repairs and let you know the results. Again, Thank You.

Oh yeah, yes, the temperature does indeed go down while traveling.

I am not familiar with the term "COP"

 

[Mjdtexan]

Ok, i pulled all plug wires one by one, stuck a plug in each one and they all fire. I know something is going on in hole number four because the little ceramic surrounding the "electrode" is discolered compared to the other plugs. Its orange whereas the others are still whiteish. Although the number 6 plug smells like fuel I know something is going on in that hole too because it is wetish, even the on the plug are wetish.

Question (more of an abservation really), I have to pull the Plenum off to get to the number 6 injector? Can injectors be tested?

I found the thermostat to be closed. I also noticed that it appears to be two pieces, is this correct or has someting happened to it?

Thank You so much for taking your time to help me. I figure you must be a technician or someting and you probably get paid for this sort of thing.

 

[Exproblems]

. I also noticed that it appears to be two pieces, is this correct or has someting happened to it?

QUOTE]

The thermostat body itself on the 4.0L engine should come out and go in as "one" piece, other than the rubber O-ring seal that you need to use in conjunction with it. Your t-stat must have broke in half it if came out in 2 pieces. BTW, the torque on those 3 t-stat housing bolts is 89 inch lbs.