I was test driving one of the supercharged bonnivilles and noticed the boost guage at idle was at about -5 is that normal? What should it be at at idle? What should it be at under normal highway driving conditions? Thanx in advance for any help!

 

I don't know what the exact reading should be, but you won't have much boost at idle. There is a boost control solenoid mounted on the side of the supercharger, and the PCM will control the amount of boost, mostly for "load" type conditions. If you stomp on it, it should go up.

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'97 Bonneville SSE

 

our gauge goes from -10 to +10. at idle, it is usually around -10 unless it is idleing high from, say, the A/C being on or something, then it will be a few pounds higher.at WOT it will go up to just short of the yellow line a little below +10. if anything seems wrong with it you may want to stay away from the car...our supercharger broke after a couple years, but luckily was under waranty because GM will bend you over for a new one. hope that might have helped.

 

oh, missed part of your post. at nornal highway cruising, assuming you are just giving it enough to stay at around 65-70mph on a flat road- it will usually read around or just short of 0.

 

Thanks guys you were more than helpful.