Vibration at 2600-3000 rpm
12-12-2016, 10:36 AM
#1
Rennlist Member
Thread Starter
Vibration at 2600-3000 rpm
Anyone experience a slight engine/trans vibration at 2600-3000 rpm range? I can make it happen in all gears at different speeds at this same rpm range, so not tires or wheel related. Happens with PASM off or on. You can feel it transmitting up through the seats and on the dash. Any ideas? Is this normal?
Carmen
Carmen
12-12-2016, 11:21 PM
#2
Rennlist Member
Carmen, is this with sports exhaust on or off? This range does have some unusual harmonics. this is the area i get most vibration through the cabin with the sports exhaust on....
12-13-2016, 10:42 AM
#3
Rennlist Member
Thread Starter
Mark,
I have the GMG center muffler delete, so it is louder than stock. In that range the valves are always closed so should make no difference and it doesn't. The center muffler is something that is easy to swap out and test. Dealership reproduced it with the car on the lift, trans in park but couldn't find the source. They loosened and retorqued the motor mounts and checked all the other connections. The PIWIS shows the variocam starting to move the cam timing in that range. I guess I will run in the new engine and see if it goes away and maybe swap the muffler when I get a chance. It is just a new noise that wasn't there with the old engine. Maybe that is a good thing!
Carmen
I have the GMG center muffler delete, so it is louder than stock. In that range the valves are always closed so should make no difference and it doesn't. The center muffler is something that is easy to swap out and test. Dealership reproduced it with the car on the lift, trans in park but couldn't find the source. They loosened and retorqued the motor mounts and checked all the other connections. The PIWIS shows the variocam starting to move the cam timing in that range. I guess I will run in the new engine and see if it goes away and maybe swap the muffler when I get a chance. It is just a new noise that wasn't there with the old engine. Maybe that is a good thing!
Carmen
12-13-2016, 05:24 PM
#5
Rennlist Member
Gotcha Carmen. Sorry - my recent experience is with DMS race headers fitted and I did notice with the valves open it makes a far more "gravely" sound and feel in that range than I noticed before. I'm not sure how the valves work with the DMS but much different than OEM.
Be interested if this goes away with a few miles. It could also be things like PDK clutch/flywheel - these are possible causes?
Be interested if this goes away with a few miles. It could also be things like PDK clutch/flywheel - these are possible causes?
12-13-2016, 08:46 PM
#6
Nordschleife Master
Mark,
I have the GMG center muffler delete, so it is louder than stock. In that range the valves are always closed so should make no difference and it doesn't. The center muffler is something that is easy to swap out and test. Dealership reproduced it with the car on the lift, trans in park but couldn't find the source. They loosened and retorqued the motor mounts and checked all the other connections. The PIWIS shows the variocam starting to move the cam timing in that range. I guess I will run in the new engine and see if it goes away and maybe swap the muffler when I get a chance. It is just a new noise that wasn't there with the old engine. Maybe that is a good thing!
Carmen
I have the GMG center muffler delete, so it is louder than stock. In that range the valves are always closed so should make no difference and it doesn't. The center muffler is something that is easy to swap out and test. Dealership reproduced it with the car on the lift, trans in park but couldn't find the source. They loosened and retorqued the motor mounts and checked all the other connections. The PIWIS shows the variocam starting to move the cam timing in that range. I guess I will run in the new engine and see if it goes away and maybe swap the muffler when I get a chance. It is just a new noise that wasn't there with the old engine. Maybe that is a good thing!
Carmen