Why would one of the manifold ports be discolored more than the others? Is this Ok? Is it normal? Thanks.

Here's what mine looks like. sorry if the picture is a little blury I took it with my phone.

 

poor pic, but maybe the gasket isn't 100% seated around that runner

 

Looks like oil is coating just that one port for some reason. Do you have a catchcan installed? What do the runners on the lower collector look like?

 

That's actually a very common feature for the VQ motor.

I open up plenums all the time and see that discoloration to varying degrees. Some engines have none. Some have a little (like yours) and some have it on every runner.

Its some sort of backfire phenomenon but I don't know the cause. It doesn't matter if its stock or fully modified with all the boltons.

Its somewhat random on which cars it happens to.

 

Goth- No catchcan

Hydrazine- think its anything to worry about or just something that happens that no one would see unless they take the plenums off?

 

Its probably not a good thing to have but its hard to quantify what it does negatively.

I'm sure the dealership would swear its completely normal and OK.

I wouldn't want it on my car but this really is such a common issue I wouldn't be too concerned with it.

 

No sure how i feel about that. Thanks for the info guys.

 

Is it oil for certain? Is it in the upper manifold as well - just for that runner?

 

Its a burn residue that leaves stains on the surface.

I suspect it may be related to preignition due to hot Platinum plugs.

Cooler plugs or non-platinum plugs "may" help.