Basically I was driving and motor started missing bad and kicked out a P0300. I let the car cool off before I was going to check out the possible east causes for the code and saw nothing. Next time I started the car up it was not missing but the supercharger had some noise internally. I have no problem buying a new SC if that is the cause but I do not want to buy a new SC if I then have to still track down the cause of the intermittent P0300. I need to fix the P0300 cause first.

Thanks, Jack

First of all, if your supercharger is making a noise (sounds like a bunch of marbles in there?) chances are all you have to replace is the coupler. Easy and inexpensive to do, and we have a write on the forum explaining how to do it.

Second, the noise in your supercharger is not likely causing the P0300 code. I would start by checking fuel pressure.

Read this thread. It explains how to diagnose a bad coupler, and how to replace it. Cost is around $50 if you do it yourself, and it is a reasonably easy fix.

https://www.gmforum.com/normal-maint...oupler-279064/

One added comment. A bad */c coupler can affect performance if the knock sensors pick up the noise and retard timing, but that should not throw a P0300 code. Most of the time when I see a P0300 code for a Bonneville, particulary a 15 year old one like yours, it ends up being a bad fuel pump. There are certainly other possible causes, but that one seems to be the most common. If you haven't changed the fuel filter lately, you might want to start with that first, but I suggest you rent a gage (I say rent, but you get your deposit back so it ends up not costing anything) and check fuel pressure.

Another added comment. If you do change the */c coupler, do not buy that expensive oil the dealer sells for the */c. Use Mobile 1 synthetic 5w-30 engine oil. You only need 1/2 a quart or so. Saves quite a bit of money over buying the OEM fluid, and it is an approved substitute used by several of our members (myself included).