Overboost
 

I have installed a new venturi plate and k & n filter in my 79 930 and now my boost is going past 1.0 when driven hard and it cuts out in the middle of acceleration. I have tried leaning out the mixture but I am experiencing the same problem. :confused:

are you sure that you didn't bump one of the vacume (sp?) lines to the wastegate? That would be my guess. Mixture has very little to no effect on boost level.

You are hitting overboost protection switch. It cuts at approx. 1.1 bar to save engine from grenading.


You have to check folowing things:

There is a hose going from intercooler to lower part wastegate bell, check for leaks, if it slipped off or is plugged with dirt.

If this pressure-line is OK then try to blow into it with your mouth, air shouldn't escape trough it. If it does, the membrane in your wastegate is ruptured.

If everything is OK, you can try to blow compressed air into this hose and listen to sound of opening wastegate (exhaust will sound different)...CAUTION! Do not use more than 1 bar or you will rupture the membrane!

Do not fiddle with mixture, it has nothing to do with boost...set it back where it was.

Good luck!