Hey guys,
I have been having some issues with my boost pressure and after searching around for a while, I think I have less of an idea of what is going on now. I'll preface this by saying I'm certainly no expert in these cars but I'm relatively mechanically inclined. The car is a low mileage, completely stock '86 930.
The other day, my car was idling funny and I noticed that the AAR was unplugged. I plugged it back in and adjusted the idle to a solid 950 RPMs. Later that day I was driving and noticed the boost gauge was moving between .4 bar at idle and .8 under full boost.
At this point I'm thinking the boost gauge sensor is acting up. I park the car and after a few hours, go for another drive. Now the gauge is at 0 bar at idle but under boost it will only go to .4 bar and no further and there seems to be a lot more lag. Doesn't feel like it is kicking the same any more or at all really.
So now I'm thinking a boost leak...I already swapped out all the intercooler o-rings in case there was a leak there but still seeing this issue. The earlier issue with the pressure being too high at idle hasn't happened again since. So here's where my head is right now:
The car runs well, starts right up, idles at 950rpm with no bounciness and is smooth all the way through the RPM range. Just low boost.
1) Possible wastegate issue...perhaps valve or worn spring? This would not explain the first issue but I guess it's possible the gauge was being flaky and corrected itself. Btw, is there some special tool to getting the wastegate off that I'm not aware of? I can't find a socket or bendy socket that fits the two nuts near the exhaust pipe bend. I can get an open-end wrench on them but not without fear of rounding the nuts. Beginning to think I'm going to have to just cut them off and replace them.
2) Could a bad boost sensor still cause the behavior I'm seeing? Initially boost pegged high and now cutting out at .4bar?
3) Something I'm overlooking/haven't thought of yet. Although I feel like a lot of other things would manifest as poor running/idle/etc.
Anyone seen this before or have any ideas? Oh, and here's a pic because I hear these help!
