I recently performed the banjo bolt mod on my leaky FPD and replaced the upper and middle plenum gaskets (s5 NA). I bought the gaskets from Atkins, and noticed that they were thinner than the ones I removed. The engine ran perfect before I did the mod, now it has a low and crappy idle. I did a vacuum leak check with propane and found one of the gasket flanges to be sucking air. I am assuming that there is some slight warpage at the plenum gasket flanges, which a thicker gasket should compensate for, much like the ones I removed. Does anyone know if there are thicker gaskets available?...I called my local Mazda dealer and they were out of stock and not very helpful either.

 

bump

 

i think the ones on ebay are thicker

 

get some gasket paper, trace the outlines onto it using the gaskets from atkins, problem solved. if you want you can even double up the gasket since you are the one making them now.

quick, simple, and will cost $5 at most....

 

If you had a vacuum leak, I would think you'd have a high idle?

 

A small vacuum leak gives a high idle, a large one can make it stall. Mine sped up to the normal idle rpm and smoothed right out with the propane. I found some thicker gasket material to make new gaskets.I'll rip it apart as soon as I feel like farkin with it.

 

Thanks guys for your input. I stacked 2 gaskets on each of the plenum halves and fixed the vacuum leak....she runs smooth as a gravy sandwich.