About a month ago I had Michael, from Euromeccanica in Mount Vernon, NY, install an Active Autowerkes Stage 1 supercharger in my 2004 BMW M3 SMG, 90,000 miles, which has been running like a top. Michael selected this unit, after reviewing all those on the market because of it's diminutive size, mostly silent running and strong construction. The car's performance now is terrific. There are no "under load" issues I feel, at all. It's a delight listening to the engine throb at a steady 80mph on the highway. However, there are a couple of idiosyncrasies that are concerning me.I have been reluctant to really push the car, because of these issues. Hopefully someone can reassure me that they are either normal or inconsequential, but if not, I am sure it would be better to fix them ASAP. 1) a few minutes after warmup, the idle becomes irregular. At lights or stop signs and when I finish running it for the day, I can hear and feel it race up approximately 200rpm, or so, and then quickly drops back, then back up, etc.,but the frequency is too short for it to register on the tach, which stays pretty steady at approximately 1000rpm. This galloping occurs 100% of the time, after warmup, when idling. Before warmup, the idle is steady. 2) If I listen carefully next to the exhaust pipe, I can hear the engine lightly cough and sputter at idle, but it does not threaten to stall 3) A high pitched repeating squeak has returned, despite replacing the fan belt that came in the kit, with a new one from AA. It disappeared initially after the re-installation, but after a few days started again. It's rate varies with engine speed. It goes away after about 10-15 minutes of normal driving. Also, I need to know if it is OK to continue adding BMW fuel injector cleaner every 3000 miles or so. And are there any modifications or adjustments to do, or signs to watch or listen for, if want to track the car in the summer's heat, or even drive it "spiritedly" in the hot weather? The car has had all the required maintenance as indicated from BMW, and far beyond that as I additionally follow Roundel magazine's tech advisor Mike Miller's "Old School" maintenance schedule. I use only Shell V Power 93 octane fuel.
This is a follow up to my original post -"Minor...", I'm using the reply tab, because I don't know how to continue, otherwise. Turns out that the uneven Idle and exhaust issues were caused by a combination of a clamp left too loose and injector leaks. The leaks had to be fixed by installing a custom fabricated aluminum spacer ring that moved the injector back about 1/16", apparently a fault in the original pieces that came from AA. During the past few weeks of use,there was an overheating problem, apparently unrelated, but coincidental, to the Supercharger install, which was fixed by replacing the fan clutch. The car was Dyno'd and produced 408 WHP and 280 lbs torque The squeal has returned, despite replacing, for the second time, the drive belt. Looking now replace the pulleys. All the above follow-up work and analysis and quite a bit more, not detailed here, was done by Mike Randowsky at Maximum PSI in linden NJ.
Thanks for the update & glad to hear you're getting most of it worked out - sorry for the lack of replies, I kinda doubt we have many active users on the forums with aftermarket-boosted bimmers to offer much insight. Adding additional replies is just fine for continuing a discussion thread, also. Hope you get the squeal fixed too!
