280z: another problem

[280zgod]

well in response to 2manyz's questions everything seems to be fine all the hoses are connected and i havent checked the timing yet but i dont think thats the problem since the car runs fine when you drive it it just has no torque i guess you could say i fly thorugh a gear and get almost no speed from it and as for the plugs the first five came out white and the sixth came out black and wet with like oil on it or maybe halfburned gas or something so that was really weird id say maybe i blew a cylinder but the car doesnt smoke and it runs fine starts easy just dont know where all my power went and why it idles at 2000rpm constantly again sigh thanks for your help ill keep trying to mess with it but if this keeps up im switching to carbs i think

[Walter Moore]

On a fuel injected engine a high idle is often associated with an air leak in or around the intake manifold. This could also make the engine's fuel/air mixture run lean which would make it run hot.

One of the most frightening experences that I ever had was when the vaccum line to the power brake booster on my old Volvo 164E broke off just as I was approaching a stop light. The engine speed jumped to 2000 or 3000 RPM and the brakes felt like they were not there... If I hadn't pushed the automatic transmission into neutral and used both feet on the brakes it would have been ugly.

On a Z, The studs that attached the exaust manifold or header are also used to hold the bottom side of the intake manifold in place. I know that on my car three of them broke off inside the head when I removed the manifolds, and I gather that this is a common problem. Perhaps after the exaust guy attached the header one of those studs snapped and he just didn't notice it. Or he could have forgotten to tighten one of the nuts. In either case, since you say that the car's performance went bad when the header was installed, and since the symptoms match what one would expect from an intake manifold leak. I would look there first.

[thefastestz]

I thought one must remove the intake manifold to install the headers since the intake and exhaust manifolds shared a common gasket. Or is this just a 240z thing? Or am i just plain wrong i wouldn't be surprised.

[280zgod]

yeah im guessing its my manifold leaking cuz i looked under the intake and to my surprise not one of the head studs had the giant washer and nut on it so i went out and special oredered the 6 of each of those i needed those washers are dang expensive man 2$ a piece so it came out to like 15 since i needed another few head studs from when i broke them hehe anyways hopefully when the parts come and i tighten down the intake my problem will be solved thanks for your input everyone and to answer the last post yes it is a single gasket for intake and exhaust you must remove both to change it thanks again later