[e90sabr]

I recently installed the three stage intake manifold on my car and had codes saying the car was running lean on both banks. I sorted that out and the last few days ive been seeing the p0458 code come on after clearing it. I see a significant decrease in fuel economy (-80 miles from my usual tank) but the car is running and driving perfectly fine. Feels smooth/quick, no idle issues steady at 600rpm).

Today I replaced the purge valve under the manifold and cleared the codes. After driving for some time (spiritedly) the code came back with p0440 (retightened my gas cap). Not sure why the code keeps coming even after I cleared it and replaced the valve.

Any advice? Please help.

[e90sabr]

I discovered that it seems like my valve cover cracked at the rear where the pcv hose connects to it. Im not sure if its related to my constant p0458 code (still persists after replacing purge valve, DMTL pump). Cylinder 1 started misfiring; when the car starts it misfires and judders but smooths out after adaptions kick in, drives okay.

Can anyone confirm this?

[TheHazelNut]

Originally Posted by e90sabr

I discovered that it seems like my valve cover cracked at the rear where the pcv hose connects to it. Im not sure if its related to my constant p0458 code (still persists after replacing purge valve, DMTL pump). Cylinder 1 started misfiring; when the car starts it misfires and judders but smooths out after adaptions kick in, drives okay.

Can anyone confirm this?

have you check the hose that leads up to the purge valve. it runs from what looks like the bottom right side of the engine bay to the junction box mounted to the intake manifold. A lot of times this hose will appear fine but develop a small flat spot which causes it to throw a code. Although I haven't heard of it causing misfires.

This thread refers to the hose I am speaking off as well as showing how small the flat spot may be. I had this same issue on my car and drove with a evap code for like 5 years.

https://www.e90post.com/forums/showthread.php?t=1487862

[e90sabr]

Originally Posted by TheHazelNut

have you check the hose that leads up to the purge valve. it runs from what looks like the bottom right side of the engine bay to the junction box mounted to the intake manifold. A lot of times this hose will appear fine but develop a small flat spot which causes it to throw a code. Although I haven't heard of it causing misfires.

This thread refers to the hose I am speaking off as well as showing how small the flat spot may be. I had this same issue on my car and drove with a evap code for like 5 years.

https://www.e90post.com/forums/showthread.php?t=1487862

Im not following which hose—when putting my three stage on, i replaced that pcv hose on the rear if the valve cover, and the hose connection to the bottom of the purge valve looked fine — any way to test this? It’s just eating away at my mileage.

[firesnatch]

Originally Posted by e90sabr

Im not following which hose

The black one with ridges in his picture, near the junction box at the bottom of the manifold you put in. Check it for damage. If you scroll further down on the thread he linked, there is a pic of the damage.

[e90sabr]

Originally Posted by firesnatch

The black one with ridges in his picture, near the junction box at the bottom of the manifold you put in. Check it for damage. If you scroll further down on the thread he linked, there is a pic of the damage.

Ahhhhh I see now! How could I access that hose to take it out and inspect it?

[TheHazelNut]

Originally Posted by e90sabr

Ahhhhh I see now! How could I access that hose to take it out and inspect it?

it may be possible to do it without removing the intake manifold however when i did it, it was during an my swap to a stage 3 im. not hard to remove just have to reach down there and disconnect it.

As mentioned it runs down the bottom right of the engine bay (perspective is you are standing infront of you car looking at the engine)