[Larryheb]

I recently installed aftermarket cats on a 2006 4.4 hse. I don’t know the previous history of the vehicle so I am a little stumped on lean codes that I can’t seem to resolve.
I replaced air filter and mass airflow sensor, fuel pump and reset engine adaptions.
I did reuse the old o2 sensors and considering purchasing a new set as I still can’t get through an emissions test. Car seems to run fine, averages 16.2mpg. Can’t find any vacuum leaks, I tried spraying starter fluid around all gaskets and hoses and didn’t change rpm or anything while engine was running.
I put injector cleaner in the gas tank drove the car a little harder and one of the codes has now changed on bank 2 from p2098 to p0430.
The company I bought the cats from
Says I will damage the cats driving with leans codes for bank 1 and bank 2.
I am hoping someone on here can tell me what is going on .
thanks

 

[MARK_C]

Lean codes come from the upstream O2 sensors. The post cat O2 sensors are only there to monitor the cats, and those give you the P0420/P0430 expended cat codes. Hows your coolant temperature? Do you ever get a code telling you it takes longer than normal to reach operating temperature something like a P2016? If the engine runs cooler than normal because of a bad thermostat or other reason that will cause lean codes, usually on both banks at the same time. Also if you haven't already done so change your PCV valve on the right hand valve cover, those get leaks eventually.

 

[lenlo]

+1 on PCV valve - LR003380

Only use OEM one.

 

[Larryheb]

Lean codes come from the upstream O2 sensors. The post cat O2 sensors are only there to monitor the cats, and those give you the P0420/P0430 expended cat codes. Hows your coolant temperature? Do you ever get a code telling you it takes longer than normal to reach operating temperature something like a P2016? If the engine runs cooler than normal because of a bad thermostat or other reason that will cause lean codes, usually on both banks at the same time. Also if you haven't already done so change your PCV valve on the right hand valve cover, those get leaks eventually.

Coolant temp says about 93 degrees Celsius at operating temperature. Gauge moves to middle point on cluster fairly quickly.
Seems to throw lean codes for both banks more at idle.
I shall pick up a new pcv valve . Do you think it’s worth changing the o2 sensors ?
Thanks

 

[MARK_C]

Nope, don't think its worth your time to change the O2 sensors. I've got 220K miles on mine and they are still on the same down stream sensors, I did change my upstreams once, but nothing changed when I was going thru lean codes. The gauge cluster is so heavily damped in the id range its not worth much in trouble shooting. The gauge will stay right over the center mark anywhere from the upper 180s to about 220F. If you have something that can read ECT as your driving (probably do from the pictures above), watch ECT temperature especially as you coast down a hill or climb up a hill. If your ECT isn't hanging right around 195F all the time (once its up to temp) then one of your thermostats is acting up. The 4.4L have two thermostats, the main one up on the top front of the engine, and another one down in the bottom left corner of the radiator that controls the tempearture of the coolant going thru the oil and transmission coolers. If that one fails open it allows coolant to bypass the main thermostat and the engine takes longer to heat up than normal, and the actual ECT will shift up and down as you drive based on engine load and outside air temp.

Also make sure you have a clean paper air filter (not an oiled K&N style filter), and that all the radiator clamps on the intake tubing between the filter and the throttle body are all tight. Clean the MAF with the proper MAF cleaner, and if need be clean the bore of the throttlebody with some cleaner and a rag. Theres some air bypasses in there that go around the throttle blade that can cause issues if they are blocked up with carbon, or other grime.

 

[Larryheb]

Nope, don't think its worth your time to change the O2 sensors. I've got 220K miles on mine and they are still on the same down stream sensors, I did change my upstreams once, but nothing changed when I was going thru lean codes. The gauge cluster is so heavily damped in the id range its not worth much in trouble shooting. The gauge will stay right over the center mark anywhere from the upper 180s to about 220F. If you have something that can read ECT as your driving (probably do from the pictures above), watch ECT temperature especially as you coast down a hill or climb up a hill. If your ECT isn't hanging right around 195F all the time (once its up to temp) then one of your thermostats is acting up. The 4.4L have two thermostats, the main one up on the top front of the engine, and another one down in the bottom left corner of the radiator that controls the tempearture of the coolant going thru the oil and transmission coolers. If that one fails open it allows coolant to bypass the main thermostat and the engine takes longer to heat up than normal, and the actual ECT will shift up and down as you drive based on engine load and outside air temp.

Also make sure you have a clean paper air filter (not an oiled K&N style filter), and that all the radiator clamps on the intake tubing between the filter and the throttle body are all tight. Clean the MAF with the proper MAF cleaner, and if need be clean the bore of the throttlebody with some cleaner and a rag. Theres some air bypasses in there that go around the throttle blade that can cause issues if they are blocked up with carbon, or other grime.

Ive ordered a new pcv valve. The ECT stays constant at 93degrees C.
The aftermarket cats seemed to have a slight leak on the manifold flanges so I did put gaskets on them .
Is it possible they could be giving me the lean codes still?
After a while I’m also getting catalyst efficiency below threshold bank 2. Is this directly related to the lean codes or could that Cat be faulty too?

 

[MARK_C]

The leak in the exhaust can defnately cause a lean exhaust code. The L322's are quite well know for getting small cracks in the body of the upstream cats and that causeas all kinds of lean codes on that side. Can't say if your cat is faulty or if its just different than the original enough to cause the P0420/P0430 codes, the system seems to be very sensitive to changes. I personally would get an O2 extension bushing befofe i would replace the cats on a 16 year old vehicle, unless there was some kind of warrantee that would pay for the replacement.

 

[Larryheb]

The leak in the exhaust can defnately cause a lean exhaust code. The L322's are quite well know for getting small cracks in the body of the upstream cats and that causeas all kinds of lean codes on that side. Can't say if your cat is faulty or if its just different than the original enough to cause the P0420/P0430 codes, the system seems to be very sensitive to changes. I personally would get an O2 extension bushing befofe i would replace the cats on a 16 year old vehicle, unless there was some kind of warrantee that would pay for the replacement.

Well, the pcv valve turned up today and I installed it .
I also tightened down the mass airflow sensor with slightly bigger screws in case that was causing the lean codes on bank1 and 2.
I drove about 5 miles down the road and coming to a junction at the top of the hill the car started bellowing out white smoke. It was very thick .
seemed to quieter down a little and then I turned round and headed home.Pulling away it smokes a lot , could this be faulty catalytic convertors?
The company in Canada I bought them from said the lean codes would cause them to overheat and melt the material inside . Is this what is happening ?
Seems to be a knock coming from exhaust system when it was smoking at its worse.
Any ideas if it’s the cats or something more terminal to the engine?

 

[MARK_C]

The new PCV valve is bad, probably has a tear in the rubber diaphragm, or the diapragm didn't get installed right when it was made, its pulling oil vapor out of the valve cover and burning it. My first replacement one did the same thing, had to get a new one. Put the old one back in and trade the new one in for another new one.

 

[Larryheb]

I put the old pcv valve back in and noticed there was a lot of oil in the hose going to the throttle body. Car is still smoking a lot. Dipstick appears to be about a quart lower . I think all that oil went into the throttle body. How do I get it all out ? Do i have to removed throttle body?

 

[MARK_C]

Don't have to remove it just use some throttle body cleaner and spray it in there, maybe use a lint free rag if theres a real lot of it. Spray out that hose as well, you can use whatever you want for that as long as its off the engine, carb cleaner, MAF cleaner throttlebody cleaner. Theres probably some down in the intake as well. It will burn off after driving it for a few miles. I lost about a quart of oil going to work the morning after I replaced my PCV valve, It didn't start smoking for about 10 or 15 miles though and then it looked like a destroyer laying down a smoke screen every time I took my foot off the gas. Put the old one back in and got a new one and everythings been fine for probably 25K miles. I can't beleive they have such a high failure rate right out of the box.

 

[Larryheb]

Thanks a bunch Mark. For help with the emissions. the prop Shafts and the transmission.
I was struggling to find a way to recode the transmission and I eventually found a way to do that with a Bluetooth OBD2 tool.
I should have taken your advice and bought a genuine pcv valve, just had a limited budget . Ordered one from Atlantic British today and has the arrow on top which I read is a better indication of a working part .
Just did an hour running throttle body cleaner and sea foam through. It did stall and of course Stu k the neighborhood out.
I checked the old reinstalled pcv valve for leaks and none were visible with carb cleaner.
I have the codes bank 1 and 2 lean after 15 mins of driving, sometimes longer . I saw smoke coming out the join down stream of cats but that wouldn’t thtow the lean code still?

 

[MARK_C]

It will throw the P0420/0430 expended cat codes but probably not the lean codes as those come from the upstream sensors unless its very close to the cat body itself. I'm assuming this is a joint from the replacement Cats, since a factory exhaust if fully welded from front to back, nothing is removable without a saw or cutting wheel. The original cats will sometimes get little tiny cracks in the welds on body of the cat itself and it will set the lean codes. I replaced the PCV valve and ran some BG44 fuel injector cleaner, marvel mystery oil, and some Lucas fuel treatment thru my 06 when I was having issues around 170K miles. I reset my fuel adaptations, and changed ignition coils (I fully loaded the parts cannon and fired it all at the vehicle) and even then it took about another week (300 to 400 miles) for the lean codes to go away. I still get the random lean code for one bank or the other but it doesn't last, and I haven't had both sides at the same time return for quite a while.

 

[gravitylover]

Slight tangent but, I've got to wonder if this chasing codes and replacing this that and everything else and still struggling with gremlins is a thing with all modern vehicles or are some more dramatically affected than others. Maybe because I read too much about these things it seems that they're more prone to it than most and are unnecessarily complicated to solve when the poop hits the fan. I've got mine to the point where it's typical age problems that any car with 155k would have but those are mechanical and not too perplexing compared to this stuff. I do huge miles this time of year and y'all have me all worried that I'm gonna be stranded somewhere due to some gremlin hiding somewhere.

 

[Larryheb]

Slight tangent but, I've got to wonder if this chasing codes and replacing this that and everything else and still struggling with gremlins is a thing with all modern vehicles or are some more dramatically affected than others. Maybe because I read too much about these things it seems that they're more prone to it than most and are unnecessarily complicated to solve when the poop hits the fan. I've got mine to the point where it's typical age problems that any car with 155k would have but those are mechanical and not too perplexing compared to this stuff. I do huge miles this time of year and y'all have me all worried that I'm gonna be stranded somewhere due to some gremlin hiding somewhere.
So these aftermarket cats bolt on to the exhaust manifold flange with 2 studs. They are difficult to align with the coned mating surface and I was feeling a slight leak so I put gaskets on there which isn’t ideal but seemed to stop the leak and couldn’t see a leak with a shop vac drawing through the tail pipe. Downstream of the rear o2 sensor there is a join that I haven’t welded yet. The replacement cats fit inside the exhaust pipe where it was cut off just before the exhaust hanger. I haven’t welded them yet as I am not convinced there isn’t a tiny leak on from the exhaust manifold flanges (2 studs)
There is definitely a leak downstream where they join with an exhaust clamp but that would have no relevance to lean codes ?
I put 2 different fuel injector cleaners in the gas tank and noticed an increase in acceleration and mpg.
The lean codes seemed to stay off for longer . But then I got the cat efficency reduced in bank 2 code.
When I changed the air filter and mass airflow sensor the lean codes seemed to go from
Just bank 2 to bank 1 as well.
I used the old o2 sensors in the new cats. They were very tight in the old exhaust and I had to knock them with a wrench and hammer to free them up. Could they be damaged ?
I have a couple more weeks before dmv suspend vehicle for no emissions. Not sure what to try next .

 

[MARK_C]

If you can't clear the cat efficiency codes go old school and get an extension bushing for the after cat sensors, its just a male/female bushing about an inch long that you screw into the pipe and then the O2 sensor into the opposite end. That pulls the sensor out of the exhaust stream and usually will fix a P0420/430 code, and sometimes lean rich codes if you do it on the upstream ones as well.. The after market cats cant be expended its just the LR equations for determining if the cats are bad or not are very specific to the makeup fo their cats.

 

[Larryheb]

If you can't clear the cat efficiency codes go old school and get an extension bushing for the after cat sensors, its just a male/female bushing about an inch long that you screw into the pipe and then the O2 sensor into the opposite end. That pulls the sensor out of the exhaust stream and usually will fix a P0420/430 code, and sometimes lean rich codes if you do it on the upstream ones as well.. The after market cats cant be expended its just the LR equations for determining if the cats are bad or not are very specific to the makeup fo their cats.

I took a screenshot of gap diagnostics tool live values at 2000rpm . Still getting lean codes on both banks after about 30-60 miles of driving. It will do it accelerating and at idle.
Is there anyway the upstream o2 sensors are on their way out or would those lean codes appear instantly if that was the case?
You mentioned something about putting spacers on upstream o2 sensors. Is that worth a try at this stage or should I just replace the o2 sensors to knock that off the list? Thanks again