95 riv s/c vibration

[gignac]

replaced worn out supercharger with rebuild unit.still have vibration under load comes in at 2000 rpm and doesnt have a lot of power.does anybody know the position of the air intake flap at idle and under load.i think it is working opposite the way it should?at idle my flap lever is straight up and under load it dropdown towards the set screw in housing..

[96riviera18]

flap? do you mean the butterfly valve in the throttle body that lest air into the supercharger? it should be straight up and down when idle (ie very little air entering the engine) you could have a bad motor mount that is causing the vibration. does the engine move(jump up) when you rev it? there are alot of things that can cause a vibration, can you be more specific? CEL on? do you feel the vib thru the whole car or in the wheel or pedels? btw our cars have a odd vibration once the trany goes into overdrive (4th) and the rpms drop. but that only happens under very light acceleration and its normal.
for example; your accelerating slow up a slight incline,once the car get to about 50mph the trany goes from 3rd gear and ~2400rpm to 4th and ~1600rpm, that drop in revs causes a vibration until you either get the revs back up higher or you dont need as much torque on the hill.
matthew

[gignac]

I meant the vacuum operated butterfly in the bottom of the supercharger.The vibration starts around 2000rpm under load.Seems to shake the whole car but more noticeable in the steering wheel.doesnt seem to have a lot of power.Denis

[96riviera18]

sounds like your not building up boost(do you have access to a scan tool?), maybe a vac leak or the boost bypass sylanoid (sp) is not working. have you done a full check of all the vac lines to make sure there are no leaks? you could run some sea foam in the brake booster line to help clean out the carbon in the throttle and around the s/c butterfly valve. also make sure the pcv is working (i dont know if that will cause vibration or not but its cheap and easy rule out)
matthew

[gignac]

thanks for the info. keep you posted Denis