Hi I was wondering if you guys had ever had a problem with the 8 white cup risers that go under the plenum cover? I've had my spacer installed for like 9 months now and I had done all my maintenance on my car and was wondering why my mpg where dropping, so I decided to clean my plenum in case there was oil (I have a catch can) or buildup. I took everything apart and it was a little dirty nowhere near before I installed catch can. I cleaned everything and noticed all of my "risers" were melted about 1/4-1/2 way. I ended putting everything back together but I'm concerned now if they are going to keep melting causing bolts too loosen up,loss of power, and possibly risers getting sucked down into the engine causing severe damage? Can you guys help me out?suggestions? I dont know if they melted because I do live in Las vegas and it gets super hot here +100 degrees.
( I emailed Tony from MD the above)

his response;Even with the super heat of Vegas they should not melt. The melting point of the internal supports is over 500’F.It sounds like you have a case of back fire. Where ignition can occur in the cylinder before the intake valves close. Backfire can be cause by dirty sparkplugs or carbon buildup on the cylinder heads. And it doesn’t necessarily have to be a loud event. It can simply sound like a chuff when it happens.Are you able to put in any kind of cylinder cleaning agent into the gasoline? Change the plugs or similar? Back fire is the only way the supports can be made to melt.
my response;
yea I've used gumout fuel cleaner and sea foam in my car. I changed my plugs 53k with ngk iridiums and I have 58k on my car now.
Tony's response;
Many times you can isolate the cylinder(s) with the back fire problem. When you open the plenum, look inside the intake runners of the lower plenum.The cylinders with back fire will leave a brown char or residue on the inside of the intake runners.

So I wanted thank Tony for sending me new internal supports great customer service. What do you guys think it is?

 

Great question about the internal plastic spacers. I'd like to know the answer as well. Tony?

 

Here is an example of what to look for.

This is a picture of the bottom side of a lower plenum. The intake runners show which cylinders were experiencing back fire as indicated by the brown residue.





This is a picture of the top side of the same plenum and the same runners. Its not as easy to see in this picture but it illustrates what to look for.


If combustion is initiated in the cylinder during the intake stroke, or any time before the intake valve closes it will result in a intake backfire. Its not necessarily accompanied by a loud bang but in any case it does cause a blast of burning fuel/air mixture to be blown back into the plenum. If it happens consistently it will cause intake runner staining and a loss of power because all the fuel and air mix is blown out and burned up before it can be used in the power stroke.

As for the cause of backfire there can be many things. Sticky intake valves, carbon buildup, hot plugs, excessive overlap or fuel with a low autoignition point. Possibly even a spark advance that is way too high. Its hard to say which one though without a detailed inspection.

If you recently used seafoam it will clean out the intake runners a bit and make them look all the same from the intake side but if you take off your lower plenum and inspect the intake runners from the bottom side. (Like shown in the top picture) It will give you a good indication of which cylinder(s) are affected.

Take your lower plenum off and take pics of the runners. Normal air inlet temperatures inside the plenum will never approach 500+'F. A consistent back-fire however certainly can.

Tony

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Tony my runners on the upper plenum did look like that.I thought it was oil that had burned up. What do you think could fix it? I did clean everything when I put it together before I emailed you. My car is a 05 350z At with 58k
untuned popcharger,5/16 plenum spacer isothermal,UR underdrive pulley,headers,resonated tp, and dual magnaflow custom exhaust.

 

The fix to the problem depends on the cause of the problem... so its hard to say with certainty. It may be possible to tune it out by altering intake valve timing.

And maybe even going through a rigorous carbon cleaning process. More seafoam or a similar process of a strong gasoline detergent.

If you have a thick carbon buildup on the cylinder heads that can easily cause it. This is my first guess at the cause of the problem.

EDIT: And always avoid filling the tank with low quality gasoline. Cheap gasoline can gunk it up too.

 

my plenum spacer is going strong far as i know

 

So I notice carbon keeps coming out I added a bottle of sea foam to my tank and added half a bottle to my vacuum line. Bought another bottle today and added the half in my vacuum and gonna add the other bottle to my tank when it goes down. The carbon keeps coming but its really light so I will see what it looks like inside when the risers get here.Thanks I will post pics.