Does the article say anything about other causes for the roughness?
I had my EGR valve replaced yet I still have the problem. I think its the EGR plate.
The long and short of the "article" (which is a bit of an overstatement in it self) is what has already been stated.
The EGR plate is the plumbing distribution system whereby the EGR is distributed to each cylinder. EGR plumbing clogs _tend_ to happen at the coldest point of the system where the carbon soot "freezes" and builds up. Often this point is at the end of the line.
R&R of the plate may require the replacement of any paper gaskets between parts that must also be disassembled for the procedure. If they don't tear you can usually re-use them without problems. Metal type or rubber o-ring type seals/gaskets rarely tear or fail to reseal until these types are much older.
The plate should be relatively easy to remove/inspect and then clean by an above average weekend mechanic. You must carefully inspect the EGR ports for any visible restrictions so that you can then be assured that this was likely the source of the problem. If a restriction is visible then with cleaning you've more then likely located the problem. If no restrictions are visible then clean it anyway and hope for the best. Plumbing clogs aren't always in a visible location.
Simply use a coat hanger rod and moderately rotor root the accessible passages. Carburetor cleaner will also help soften deposits and make for a more thorough cleaning.
Specific to your question of other potential causes, unfortunately the list is rather long. And unique as the Insight is more complex then average. In all cars with this type problem, unless a pattern failure can be established (and there are always cars that are the exception to the pattern) you must "solve" the problem by a process of elimination. Usually start with the easiest/lowest cost then work toward the more difficult/expensive. Also this type of problem is one of the most complex because it must also be quantified as to its severity. Certain types/degrees of roughness/harshness have overlapping causes. Without a road test, maybe an _extensive_ one depending on many specifics, no clear direction for troubleshooting will emerge. Then your back to square one and must begin by the process of elimination.
And specific to _your_ vehicle, the modifications you have made can have unforeseen side effects. So all bets for a simple fix are off.
If you've tried the Chevron Techron or BG-44K fuel additive, inspected the air filter and generally looked the engine over for potential problems, and inspected the spark plugs then its time for the tougher inspections. Remember the spark plugs for the Insight are indexed and must be installed in their correctly matched holes.
There isn't much else I can say to help you or anyone else with this complaint blindfolded and by remote control. <g>
And I will be reading here to hopefully learn what ultimately solves your problem.
HTH!
John K. Bullock
aka. Insightful Trekker
