Hello, I just got a spare m62 off a 92 ssei at a local u pull place for 35 bucks, great shape, no slop in the nose drive. Got it home, ordered a 2.1" pulley swapped it over from the 2.55 stock. Got it zipped on bolted down and it had no whine or boost at all. Ok pulled it off cleaned and lubed the bypass it was stuck. Replaced the BCS with a spare and boom I can make boost. pushing 11+ pounds (Yes i have done most of the required things first already have new intake set, and autolite 104s and the such. Has a half inch shorter serpintine belt on it so its good and tight, My problem now is I can hear the whine but it seems faint and my boost gauge is showing positive boost but its not fast its way slower than it was stock. Its acting like the boost is dissapating. The arm extends and everything. Any suggestions? Is the computer telling it to dump boost? Its a 93 Park Ave Ultra with a 94 block. Thanks Taylor

I don't think the PCM controls boost. I believe its all mechanically controlled based on engine vacuum? Does your BCM have a solenoid with like 2 vacuum lines attached?




As far as the whine goes, does it seem to not as loud as the previous one?

Pull the vacuum hose off the BCA, plug the hose (so you don't have a vacuum leak)and take your car out for a spin. You should have full boost.

Do not leave it like this for more than a spin around the block.

When you disconnect the vacuum hose, if the arm on the BCS fully extends at idle (engine on, in park, hood raised for observations) and when you drive you have full boost the problem is the BCA.

I'm going to go out on a limb here and say I don't think boost is your problem. With that small pulley you may being getting pre-ignition and the knock sensors could be pulling timing. You need to scan for knock retard.

Try putting the stock (2.55") pulley on and see what happens.

Mike is correct. PCM does not control boost. Vacuum to the BCA controls boost. High vacuum (idle), no boost. Low vacuum (WOT or vacuum line removed from BCA), full boost. That'* why pulling the vacuum line from the BCA will give you full boost at all throttle positions.

I am thinking you dropped the pulley down WAY too small. There was only one (former) member I recall that hit the pulley limitations of the Series 1, and he had a LOT of other modifications done, including extensive porting. His track times favored a 2.3" pulley with more aggressive timing. He did indicate that the 2.0" is not only redlining the supercharger, but there was no further gains, as all that was happening was that the supercharger was creating so much heat, it became horribly inefficient (i think this is what is happening).

If you are making 11lbs of boost, and having this problem while under 11lbs of boost, I don't think the BCA is your problem.

What other mods do you have?

Heres my current setup: 180 thermostat, replaced intake gaskets, o2 sensor, coolant temp sensor, sparkplugs (autolite 104s) new plug wires, removed cat converter, thrush turbo muffler, cleaned the throttle body, new motor mount, fresh coolant, oil change 10w30 conventional. It runs like a top with the original blower and pulley on it. Pulls REAL hard. With the pulley (2.1") I got a half inch shorter belt to compensate. It WAS creating boost but now my gauge doesnt go past 0. I got the bcs/bca working properly. It pulls good then bogs. Hooked it up to a Snap On "Brick" scanner, when it bogs it hits in the upper teens (16-19) on knock retard. OUCH. Thats not good. I plan on pulling this blower off until i can get it situated and run the stock. I havent driven it much with this issue dont want to blow it up. Its confusing me why my gauge wont show boost all of a sudden. I did have the upper plenum gasket fail a week ago causing it to run lean and it compensated with extra fuel blackening all the plugs. Im going to replace them again to get a fresh set in there. I do have some exhaust leaks as well down past the 02 senor not sure if they could also contribute to the issue. I realize i went pretty radical on the size drop but the recommened drop was 2.2 I figured the 2.1 wouldnt hurt. Guess I was wrong. Live and learn. I do daily drive it but its a project car. Sorry for such a lengthy post, and I greatly appreciate the responses. Everyone is very helpful!

Just to clarify I did get a new plenum seal when it started leaking along with the o rings for it. Used the FelPro set from Oreillys. Im going to replace it again when i swap blowers over again just to make sure i get a good seal

Also have built myself a custom Fender Well Intake with cone filter on it as well to help get cooler air into the blower

All of those mods and nothing'* been done with the PCM to accommodate them. You gotta tune for all those mods. Even a CAI can have an effect with your LTFT'*. (long term fuel trims) if you don't tune.

I'm not sure if your boost gauge is mechanical or is driven via the MAP sensor. I'd start there.