My 86 951 is overboosting and cutting the ignition. Is their a way to check the codes from the KLR? This only occurs in 2nd, 3rd, and 4th (haven't tried 5th) gears between 4500 and 5000 RPMs. It is drving me crazy. I have been searching for vacuum leaks and have noticed a possible problem. Under the manifold toward the fire wall there is a rubber hose about an inch in diameter that has an elbow. It appears to go from a metal pipe to a disc shaped piece. To rplace it, would necessitate intake manifold removal. What is this disc shaped piece?
I have a track weekend in a month and I would hate to show up in a rented Hyundai 8))).

Thanks

 

Most likely you have a cracked or leaking wastegate-control line. If you look below your exhaust manifolds to the left under the firewall, you'll see the wastegate (has cooling fins). There's a rubber line on top which goes to the cycling-valve (CV) under the intake manifold. Make sure that line is OK. Then make sure the line from the CV that goes forward to the banjo-bolt on the turbo-to-intercooler pipe is no leaking as well.

Another possiblity is that your wastegate is broken and stuck closed (not likely). Most of the time when they fail, they open too soon, not too late.

You can check DME/KLR codes with the troubleshooting guide from my website http://members.rennlist.com/951_racerx