Can tuning help with a vibration?
Thread Starter
Launching!
Joined: Oct 2009
Posts: 235
Likes: 0
Can tuning help with a vibration? My car has a vibration that is RPM dependent. It seems to come and go through the range being the worst around 2500-3000RPM. I have replaced the vibration damper and it has a new FW/clutch/PP that were balanced together.
Could the vibration just be the harmonics of the engine made worse through poy mounts and a semi solid transaxle mount? or, can it be the fuel trim in the tune? If anyone has other ideas I would be glad to hear them.
Thanks.
Could the vibration just be the harmonics of the engine made worse through poy mounts and a semi solid transaxle mount? or, can it be the fuel trim in the tune? If anyone has other ideas I would be glad to hear them.
Thanks.
TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
Crank harmonics/oscillations are not felt within the car as vibration.
Does it happen in that rpm range when free revving (something is out-of-round/balance) or when under load (misfire)...?
Does it happen in that rpm range when free revving (something is out-of-round/balance) or when under load (misfire)...?
Thread Starter
Launching!
Joined: Oct 2009
Posts: 235
Likes: 0
Thanks, for the replies. The vibration comes in and out at the same RPM's under load or not, going up the band and when coming back down. The Flywheel/pressure plate/clutch assembly was sent in to be checked for balance, it was balanced. I put on a new vibration damper with no change. I do have poly transaxle and motor mounts. It happens when still and the clutch is in so it is not the drive shaft or transaxle.
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Verdad Gallardo TECH Senior Member
Joined: Apr 2002
Posts: 6,080
Likes: 17
From: So.Cal.
he has a transaxle, his driveshaft is located in a rigid tube running between engine and transaxle (on his 944);
and earlier he said this:
Thread Starter
Launching!
Joined: Oct 2009
Posts: 235
Likes: 0
Can the fuel trim at the RPM when the vibration happens cause a vibration? There is some roughness to the idle, or it may be from having semisolid motor mounts. I had a mail order tune done, but not street or dyno tune.
Thread Starter
Launching!
Joined: Oct 2009
Posts: 235
Likes: 0
I pulled the plugs and they look good, the insulator was just a little tan colored. New NGK plugs with new MSD plug wires. I pulled on fuel injector connector at a time, each one was essentially the same. Then I pulled the serpentine belt, no change.
Can a street tune be useful?
Can a street tune be useful?
Thread Starter
Launching!
Joined: Oct 2009
Posts: 235
Likes: 0
I still have the vibration when the motor is under load around 3K RPM and when the RPM's come back down through 3K off throttle. Does that indicate an ignition/tuning problem? If it is then I will take it to a tuner. If not I am going to take the preload plates off the energy suspension motor mounts. Any help is appreciated, I don't want to remove the motor mounts.
The clutch/FW/PP have been off to check for balance and the vibration damper has been replaced with a new unit, no change.
The clutch/FW/PP have been off to check for balance and the vibration damper has been replaced with a new unit, no change.
TECH Addict
Joined: Aug 2005
Posts: 2,305
Likes: 126
From: Monroe,NY
It could be one of your coil packs going bad.I had this problem.I never had any codes.I found it by taking a temp gun and checking each header and found one temp lower than the rest.Coil 8 was bad.The coil worked fine at full throttle but not part throttle or idle.It took me awhile to figure it out.
