Over the last two weekends I upgraded to 6-rib and the STB transition kit. After the 6-rib installation the car ran real well no vibrations/noises of any kind. I think I commented to Brant on how smooth the car ran. After the STB transition kit installation, the car has low humming vibration very apparent in the 2500-3000 RPM range cruising in 4th gear. It is definitely a rotational type humming w/vibration present and not a metal-to-metal vibration or rattle that comes and goes at a certain RPM. All the bolts on the HBA, IPA have been checked and double checked for tightness. The belt is aligned well and increasing/decreasing belt tension doesn't seem to make any difference in the sound/feel of the vibration. The presence was noticed right after the installation during a test drive. The STB kit definitely helped my idle dip. Additionally, the SC seems to have more of a low grinding sound at idle than I noticed before. The gear grinding noise seems to go away or at least seems diminished by the SC whine under acceleration.

Would it be helpful to record this sound for analysis? Are their procedural steps can be taken to diagnose such as removing the belt, zip tying the by-pass open etc. I was thinking taking the SC, idler pulley/belt assembly out of service and would help to eliminate any other potential sources. Any thoughts or insights would be appreciated.

Steve


2003 Special Edition, MP62, 6-Rib (1.93), SS AIC w/550 cc, STB w/transition kit, TDR A/A, PWR Radiator, Autometer Boost & A/F gauges, ACT HD, Borla "Sport" duals, HDDD, Goodyear F1-GS/D3, 16" Kosei K1s

Update: without the belt (its history) the vibration noise is still present. I have the by-pass zip tied open. At least I think it is, I rotated it counterclockwise and secured it. At least with the 6-rib addition, I still have power steering, don't need the A/C. So, this is good news.

Maybe the IAC? It makes a low humming noise when it's going bad.

Can you feel the vibration in the gas pedal? steering wheel? shifter?

I'm going to drive it a while w/o SC and see what happens. I kinda doubt it is the IAC since it was working at the DTB and its working on the STB. I am going to need a new belt though.

I installed my used 6-rib MP62 on my 2000 over winter. Every thing was great. Last week I decided to try installing the manifold heat shield back on the car - with suitable modifications. When I pulled the supercharger I found the third stud on the HBA, the one nearest the back of the car, had sheared off at the head and disappeared.

A friend helped me get the stud out and reinstall the supercharger. After the re-installation I had serious engine vibration. Like BAD. I couldn't find anything wrong.

I decided to remove the supercharger and reinstall from scratch. I changed nothing on the third install but after it, the vibration was gone.

I have no explanation but heck, a couple of hours under the hood ain't so bad is it.