LFX engine emissions question (Page 1/2)
Daryl M APR 18, 10:55 PM
I finally got the LFX out of the donor car (2013 Impala). My question is, the air pump check valves are in a very inconvenient place and will complicate the swap. Can these valves be removed or relocated? I live in Phoenix, where emissions are checked, so I need to be able to pass the emissions inspection. Any thoughts?
Joseph Upson APR 20, 08:23 AM

quote
Originally posted by Daryl M:

I finally got the LFX out of the donor car (2013 Impala). My question is, the air pump check valves are in a very inconvenient place and will complicate the swap. Can these valves be removed or relocated? I live in Phoenix, where emissions are checked, so I need to be able to pass the emissions inspection. Any thoughts?



Air pump? You must be referring to the electric vacuum pump for the brake booster, that's the only pump I'm aware of on the 3.6L although I've only seen it mounted at the front of the motor on rear wheel drive applications. Any pictures?
Daryl M APR 21, 12:59 AM
The pump is listed in the Rockauto parts list for a 2013 Impala( my donor car). It appears to be an electric pump that pumps to a servo valve on each head. I'm not real sure about how the whole thing works, but the valve on the front head protrudes straight forward. Would be nice if it could go away or at least be relocated to a more convenient location.
Daryl M APR 21, 01:16 AM
https://www.rockauto.com/en...air+/+smog+pump,4920

https://www.rockauto.com/en...ump+check+valve,4912

These are the parts I'm talking about.
Daryl M APR 21, 02:57 AM
I've done some digging online. The 2013 LFX engine has 3 versions, nu5, nu6, and nt7. The nt7 is the federal emissions version. The nu5 and nu6 are California emissions versions, one for plain gas and one for e85. What I would love to know is if the nt7 has the smog pump. My version is a California version. Would be nice if I could just remove the pump, valves and associated plumbing and be done with it.
Joseph Upson APR 21, 07:08 AM

quote
Originally posted by Daryl M:

I've done some digging online. The 2013 LFX engine has 3 versions, nu5, nu6, and nt7. The nt7 is the federal emissions version. The nu5 and nu6 are California emissions versions, one for plain gas and one for e85. What I would love to know is if the nt7 has the smog pump. My version is a California version. Would be nice if I could just remove the pump, valves and associated plumbing and be done with it.



Very interesting considering VVT was supposed to eliminate pumps and EGR valves. I would put my money on the pump version being California only. One of the Rockauto links you provided actually lists the NU6 RPO code and since you point out that NU5 and 6 are California I'd expect them to be uniform. Not sure you are aware of it but when you click on the highlighted part number on the left end of the part description it gives a drop down box of all the applicable cars by years. The parts only apply to the Impala and the Lacrosse spanning only 2 years.

I checked car parts and ebay pictures and have not been able to visualize the pump on the motor. The Impala is a test bed car apparently as it was one of the two platforms the cylinder select version of the 3900 was introduced in. This could also be a carry over as a result of the Impala being used as a police vehicle and other city/industrial service. You should be able to delete it by plugging in a PCM from an Impala that does not have it of the same year.
Daryl M APR 21, 07:06 PM
The PCM is going to be reprogrammed to be a stand alone. Removing the pump and valves should be easy. Just need to make plugs to block the ports in the heads.
Daryl M APR 21, 07:32 PM
file:///storage/emulated/0/Download/7810_712123_01_web.jpg
I found this photo on carparts.com. It shows a federal emissions LFX head. The port where the valve bolts on was never machined open. I take that to mean that I can remove the pump, valves and associated stuff and plug the ports and be done with it. What are your thoughts?
Joseph Upson APR 21, 09:29 PM

quote
Originally posted by Daryl M:

file:///storage/emulated/0/Download/7810_712123_01_web.jpg
I found this photo on carparts.com. It shows a federal emissions LFX head. The port where the valve bolts on was never machined open. I take that to mean that I can remove the pump, valves and associated stuff and plug the ports and be done with it. What are your thoughts?



Try and map out the passage route to make sure you don't need to address the other end after doing so. I can't begin to imagine what the dynamics are considering I had no idea such application existed. Just be mindful to do your homework on the PVC system and try to improve on it where necessary. Regardless of what anyone says, any direct injected gasoline motor without a combination port injector needs to have an exceptional oil catch system to reduce oil misting from the valve cover vent from entering the intake because there's nothing to clean it off the top of the valve as it builds up over time. Some engines are worse than others to the point of manufacturers either recommending a top engine maintenance service, or encorporating a port injector along with the DI.

The 3.6L shows just how important the PVC system is. If you remove the valve covers from a moderately used motor, you will observe that the top of the cylinder head that has the PCV valve will be darker in color as a result of the low to no airflow over the head due to the partition in place walling off the PCV valve at the rear (at least on the LLT motors) that only supports airflow over the left cylinder head (PVC is on the right). Some examples have a considerable oil sludge build up on one side as a result of the contaminants settling on that side and reacting to form it although most likely due to conventional oil use.

Daryl M APR 21, 10:59 PM
Near as I can tell, the smog pump is separate from pcv. The pump seems to be putting air from the air cleaner into the exhaust manifold, metered by the electronically controlled valves on each head. Does this sound right?