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View Full Version : M50 weird actions at 2k rpm, no load...



billb
05-01-2006, 03:34 AM
Guys,
Long time, no talk. Here in NC, all E34s are now old enough to no longer require an emissions inspection. I was pleasantly surprised to have a $9.10 charge instead of the usual $30...

Anyways, yesterday, my wife drove the 525 to church (just about 3 miles away; Web and I were running behind). She said on her way it began to make a "swish, swish, swish" sound that got faster as she went faster, then it went "POP". I'm guessing it was a rock (or rocks) in the tire and they got slung out, as I couldn't reproduce the sound when I drove it home from church. I thought about the flex disc, but I tried hard accelerations and decelerations and couldn't bring on the noise.

Once I got it back home, I was checking the engine's operation in the garage. I noticed something I've never really paid attention to. In park, I revved the engine to 2000 rpm. It then immediately and suddenly dropped to 1500 rpm (same throttle setting). Is this Vanos in operation, or is it just the DME richening up the part-throttle mixture? I could sneak it right up to 2000 rpm, but as soon as I hit it, it would drop off. If I went on up to 2200 or so, it didn't seem to drop off. Weird.

Haven't seen this discussed before.

BTW, the repair job on the deer hit looks great. The only problem is a clicking door where the previous owner let the door brake screws get loose, and the metal is starting to tear. Guess it's time for one of those big daddy door brake reinforcements.

billb
05-01-2006, 04:07 PM
Wow...

billb
05-02-2006, 05:59 AM
I'm more curious now that over 40 people have viewed this topic, and no one has a comment...

trumpetr
05-02-2006, 11:52 AM
I'm more curious now that over 40 people have viewed this topic, and no one has a comment...

Not sure if its the same thing,,but it got me to a-wonderin'..
My 95 525ia has been doing a weird thing,,,while driving,,,after the tranny finishes its shifts and at a steady crusing speed of say, 45mph,,,,when i give it acceleration to just before the tranny kicks down,,,,as the rpm gets to about 2300-2500,,,it starts to do a dance and fluctuate the rpms by 500, like a surge,,,untill it hits 2600 or so. If i floor it and it kicks down,,it climbs up fast (real fast) with no surge. Granted,,I recently put in an EAT chip,so,,wrote this off to the new chip learning how to feed the engine.
Trying to reproduce the same things you talked about,,,,,while parked,,and giving it acc pedal to up to 2000,,,,2500,,,3000,,,,,,it doesnt surge, pop, fart or anything.