Clean primary intake valve but ulgy secondary valve?

[Tx_Diablous]

I have never been a big fan for IMRC delete for a DD, but am in the process of installing a fresh rebuilt engine and notice on the old one I am removing that the secondary intake valves look like s*** and the primary are as clean as a baby's butt. Could this be a sign that the IMRCs are not working or just a by product of the way the system works? I have data logged this engine many times and the computer always has shown the IMRC opening as they should. I find myself thinking maybe I have wrong about deleting them and now thinking maybe I should.:shrug:

 

[na svt]

That is a by product of the design; no fuel in the port = nasty build on the valves. Deletes will help, but not completely solve the problem.

 

[MouTine]

How often should secondary ports and valves been cleaned? With and without EGR?

 

[Tx_Diablous]

Not an easy question to answer. The engine that looks so bad is a 96 and the other engine which did not look near as bad is a 98. Both have about the same same mileage but the 96 looks like hell. Now having said that there is a differance in the butterfly design between 96 and 98. The 98 is always closed until the IMRCs open and the 96 are about 20% open all the time. Logic dictates that its the 20% open causing the problem....I am just not sure yet. Another note is that both IMRC were clean and needed little cleaning. Odd though the 96 needs less cleaning than the 98 almost like the valve is taking the hit on the 96 and the IMRC is taking the hit on the 98.

 

[tt54l32v]

sounds like the 96 was just open more is why the valve is dirtier than the butterfly.