hachiroku

unless you have a specific vacuum leak at the intake manifold flange to bank 2 head, your issue would be your oxygen sensor itself. or a leaky injector seal at the head. both would be easily diagnosed by spraying brake cleaner in the area.. oxygen sensors can cause misfire issues and is the first thing to replace as its generally the culprit. the intake manifold shares a plenum for bank 1 and bank two so any vacuum leak would generally cause a lean code on both banks over time.

jpman

I finally got to the bottom of this a couple of weeks ago, and felt I owed it for any fellow members who run into this issue.

and the winner was... the intake manifold had a huge crack on the throttle plate. Luckily, RMT is local to me so I had them rebuild the whole intake manifold. Came out looking awesome!

no more hiccups on restart or misfires - also, the idle now is a smooth as butter.

Rovel

Glad to hear that you solved it. Did they replace just the plate with their metal one or what do you mean by “rebuilt entire IM”?

almostordinary

I had RMT go through my Intake as well. For me they replaced the internals with the metal plate, refurb/replaced all the sensors on the outside of the intake. Repaired a small pit in the bottom of the plenum and replaced all the gaskets as well as helped w a rethread.

Only thing I wish they didn't do was paint it, it looks fine, but the grey is slightly off from the stock grey and visually mine was mint. Good bang for the buck though if you don't want to open it up, and especially if you have any physical defects.

Rovel

1.5 years ago I opened mine up to wash it and noticed a sign of corrosion. Planning on opening it up again and painting inside myself. I also don’t want to paint the outside for OEM look.

almostordinary

Yea mine had one small pit on the inside.

I just had to take mine apart mysel as I had a throttle body go out.

Was really odd, the inside was totally mint, both TB's had zero wear or oil on the plates, looked brand new.

The front TB did have aluminum oxidation on it, swapped out w a super low mileage CL63 TB slapped it together and code's gone.

The IM is actually really easy to work with, just have to take your time and take pictures to make sure you put it all back together.

hachiroku

whatever you do, you'll need to make sure it is moisture, fuel, oil, oil vapor stable. my guess is that magnesium doesn't do well with the oil vapor that is heated and distributed through the PCV system. its usually foamy and a shade of mocha latte.

jpman

Replaced their plate with metal, light blast of manifold and paint together with new silicone sealing around all crevices or mating features.

jpman

Yeah, I opened up mine about a year ago. If I showed you the pics of the plate a year later (today) you would not believe how quickly that deteriorated.

I too wanted to OEM paint, but the light blast and respray they do slows down the corrosion. Prefer to have a deterrent to the corrosion over the looks.