I spent all friggen day on this statesman and im just about sick of it. EGR valve blocked or not blocked, the engine revs go up to 1200-2400RPM. Change and measured the length of the idle control valve and it makes no difference. I even found one very poor hose thats about 150mm long that goes from the manifold itself and has good vacuum and this hose goes to the air cleaner side of the MAF pipe but I cannot understand this. Why would you want to have vacuum going to the front of the throttle body not the back? But anyhow I changed it because it was brittle and it made no difference. The REVS still goes up to 2400 or even 2600 or even 2700 but sometimes it goes back to the correct idling which is around 900 RPM.
Now this problem is very very very erratic. Sometimes you start the car when hot and it stays and idles at 900. Then after 5 minutes it goes up to 1000 then 1100. Before you know it, its idling at about 1800. After doing this madness all day, Im now going to change the mid LIM gasket.
See with the LIM gaskets you have the gaskets going from the bottom inlet manifold to the heads on either side then you have the mid chamber. Those gaskets are either o-ring or cardboard. Then you have the top which is the top plate. Yes its like a plate which is normally o-ring. So what happened, when I ordered the LIM gaskets, I told the guy at Autobarn very clearly that this car has a different engine in it. Not the original engine so I told him I need o ring up the top, cardboard in the middle and cardboard on the head side. But unfortunately they gave me the wrong gasket. They gave me o-ring up the top, o-ring for the middle which you cannot use on this manifold and the cardboard or whatever down the bottom where the heads are. I was not happy with the quality of the old mid gasket because it was poor and without no doubt, if a part of it has been sucked in. Well this is the problem. Because as far as im concerned. If you have a hole in the pipe, you should have high RPM all the time but not this as it starts most of the time with low RPM and when the car heats up the RPM goes up.
It could possibly be another issue. The ECU or PCM or other because i have never experienced in my entire life a stubborn car like this. A car that I told my son not to buy anything without speaking to me.
We are gonna order a new top manifold gasket set with the o-ring up the lid and the mid to have the cardboard or whatever. I think the original one has cardboard mixed with some steel around the outside to keep it in the middle. Anyhow rest from here until Monday for the Bathurst weekend. I'll let you know how it goes next week.