My '91 745t drops to almost nothing on the tach when initially started and without touching the throttle it jumps up to about 800-900rpm after only a couple of seconds. On occation it doesn't quite make it up to idle and dies but starts up again. It does this really low idle every time it is started. I do have a boost problem somewhere- the car just doesn't have the power it should, but I'm not sure it's related. I have a sucking noise under boost and a slightly different sucking noise when I release the throttle. I just changed the CBV (had a hole in it) but with only slight improvement. I will be pulling all turbo related hoses off and examining them for defects. I also believe I have an exhaust leak close to the manifold but while I can see this causing a lack of boost problem, I'm not sure it would affect the idle. I had two cracks in the manifold welded but it still sounds rather noisy to me. When I put the manifold back on (used new gaskets of course), I couldn't remember if the fat washers were put on before the thinner washers or if it was the other way around. If they were put on in reverse would this create an exhaust leak? If someone can wade through this post and answer even some of my querys I would be very thankful.
Peter Mac
"91 745se