Engine Vibration

[More Power Man]

I'm new to owing a Porsche and I have a 2003 Boxster 2.7 with 76,000 miles. The engine has a vibration from 2800-3200 RPM with the greatest vibration at 3000. This is indeed an engine vibration because it will happen in any gear, neutral or with the clutch depressed. I replaced the front engine mount and that made an 95% improvement. Being a pilot, I know that with certain Lycoming engines (horizontally opposed 4 cyl) there is a limited time(5 minutes or so)of operation during flight and a yellow arch on the tach around 2100-2300 RPM because of an inherent vibration. These Lycoming engines were only produced for a few years and are only in a select model of aircraft. This is not a defect but just a part of normal operating procedures for the aircraft and that is stated in the manual. I was wondering if the 2.7 has a similar inherent problem or is this a sign of an impending catastrophic failure? The last oil change showed no signs of metal in the filter or oil. If anyone has experience with this, your input will be appreciated.

[JFP in PA]

It is definitely not normal, I'd start by checking the other mounts to see if they look beat, I'd also connect a scanner with real time PID capture capabilities and run the car through the problem "zone" a couple of times to see what the sensors are saying........

[txhokie4life]

It is definitely not normal, I'd start by checking the other mounts to see if they look beat, I'd also connect a scanner with real time PID capture capabilities and run the car through the problem "zone" a couple of times to see what the sensors are saying........

Agree -- this is not normal.

The vario cams kick in at this point.. Is it possible one side it working (or slow to work) but the other not? Sort of throwing things off balance if you will.

Mike

[spongebob]

I would say that this is not the normal way an engine should behave today,absolutely not a Porsche engine at least.

But from what I have read on several forums and from my own experience I would say that it is a wellknown fact that this happens, especially on 2,7 engines ( my own theory is the longer stroke here)

Variocams adjust earlier and later but not at 3000 rpm. Only thing that happens at 3000 is that the resonance flap moves in the air intake system.

I will not be cured by new engine mounts but probably more difficult to notice after a change.

I have also tried a new DMF without the slightest difference.

[catmanluge]

Some have cured the problem by welding a baffel inside the muffler. In fact I had the same problem but it was gone after I put on an aftermarket exhaust system.

I would say that this is not the normal way an engine should behave today,absolutely not a Porsche engine at least.

But from what I have read on several forums and from my own experience I would say that it is a wellknown fact that this happens, especially on 2,7 engines ( my own theory is the longer stroke here)

Variocams adjust earlier and later but not at 3000 rpm. Only thing that happens at 3000 is that the resonance flap moves in the air intake system.

I will not be cured by new engine mounts but probably more difficult to notice after a change.

I have also tried a new DMF without the slightest difference.

[spongebob]

I did notice a change in the way the vibrations behaved when changing from base to "s" muffler.

Must be related someway, internal design is similar but maybe it was mounted slightly different

A lighter muffler would put less stress on the rear tranny mounts giving them more room for absorbing vibrations instead.

Do you have any idea where this baffel was positioned inside ,must trie it as I have run out of ideas .

Some have cured the problem by welding a baffel inside the muffler. In fact I had the same problem but it was gone after I put on an aftermarket exhaust system.

I would say that this is not the normal way an engine should behave today,absolutely not a Porsche engine at least.

But from what I have read on several forums and from my own experience I would say that it is a wellknown fact that this happens, especially on 2,7 engines ( my own theory is the longer stroke here)

Variocams adjust earlier and later but not at 3000 rpm. Only thing that happens at 3000 is that the resonance flap moves in the air intake system.

I will not be cured by new engine mounts but probably more difficult to notice after a change.

I have also tried a new DMF without the slightest difference.