Noticed that my stock exhaust manifold was cracked this weekend. Crack is on the top of the manifold in the middle where it dumps into the turbo. The only mods that i have are straight pipe 3" duals, cold air intake, and Superchips programmer. Truck is now having a terrible time getting over 60-65 mph on the highway while towing a load. Black smoke rolls out of the exhaust when i put the hammer down, but the truck does not gain speed. I am getting a diagnostic code of P0222 on my programmer also. Something about my MAPP sensor. Does this have anything to do with the turbo not getting enough boost becuase the manifold is cracked or do i have a seperate gremlin on my hands? I am really confused here and need some advice from any member who may be able to help. Also was wondering if it would be a good idea to get an aftermarket exhauast manifold or just another stock one. If I do need an aftermarket manifold which ones are the best and what price? Hopefully the info on my mods will help with your decisions. Also, I have had these three mods on my truck now for about two years with no prior problems with the exhuast manifold. Is this a common problem. Any feedback would be great. Thanks.

 

This is a fairly common failure. This would be a separate failure from your mapp sensor. The sensor is on the left near the lift pump. not to bad to replace yourself, but buy borrow or whatever a socket big enough to fit it.
I replaced the exhaust manifold with the 3 piece manifold from ATS. (my 98.5 24V) www.ATSDiesel.com This was a great change out. The ATS manifold is just better shaped than the stocker. The stock turbo hits sooner and performs better. They have a kit for the change. Their web site says all the new manifolds come pre drilled for a thermocouple now. When I got mine it was an option. I'd also say if the top is cracked the bottom is worse on the stocker. When mine went I could almost break it in half when I got it off. You will need to do both. The performance will come right back up with those things done.

 

I bought an HTT manifold and it was already put together and was pre-tapped for my EGT gauge. Easy install, price was fair and no problems since. It too is a 3 piece design to expand/contract as it heat cycles so I don't forsee any more problems with it.