10-06-2011, 04:01 PM
I just dealt with a intermittent bad coil on mine. I'm pretty confident that's the problem you're having, the best way to check is to find someone in town with a 96-99 M3, 328i, an E39, etc etc that you can borrow a single coil out of. Swap it in with the one you suspect is the culprit and take it for a quick test drive. I'd do that before going into the fuel or anything else, just to save you a whole lot of time.
It sort of sneaks up on you when they fail like that. This summer my car was just ever, ever so slightly stuttering when i let the clutch out, or losing power if I gave it a lot of throttle. The last time my coils failed they FAILED. With them 100% dead it was easy to figure it out, but when the one went out this time I was going through the MAF, the ICV valve, searching for vacuum leaks and running down a dozen other dead ends before I came back to the coil.
One indicator of VANOS getting old is a grinding/clacking sound on start up (e39 M5s get this baaaad), or a weird sound returning to idle (mine does this sometimes I think). A car with a bad VANOS unit will feel off, and less powerful, but it should still run okay. Its just not advancing the timing to give you more power higher up in the rpm range. I think mine makes noise but it still runs strong and I can tell when vanos does its magic around 4k. Rebuilding it is on my long, long list of things to do, but not planning on it anytime soon.
It sort of sneaks up on you when they fail like that. This summer my car was just ever, ever so slightly stuttering when i let the clutch out, or losing power if I gave it a lot of throttle. The last time my coils failed they FAILED. With them 100% dead it was easy to figure it out, but when the one went out this time I was going through the MAF, the ICV valve, searching for vacuum leaks and running down a dozen other dead ends before I came back to the coil.
One indicator of VANOS getting old is a grinding/clacking sound on start up (e39 M5s get this baaaad), or a weird sound returning to idle (mine does this sometimes I think). A car with a bad VANOS unit will feel off, and less powerful, but it should still run okay. Its just not advancing the timing to give you more power higher up in the rpm range. I think mine makes noise but it still runs strong and I can tell when vanos does its magic around 4k. Rebuilding it is on my long, long list of things to do, but not planning on it anytime soon.
Now: 07 Porsche Cayman S | 18 VW Tiguan
Then: 18 VW GTI Autobahn | 95 BMW M3 | 15 VW GTI SE | 12 Kia Optima SX | 2009 VW GTI | 00 BMW 540i Sport | 90 Mazda Miata | 94 Yamaha FZR600R | 1993 Suzuki GS500E | 2003 BMW 325i | 95 Saab 900S