New 997 owner (long time lurker, first time poster) - Engine Idle Question
10-17-2012, 12:37 PM
#18
Burning Brakes
10-17-2012, 12:57 PM
#19
Race Director
RPMs sit right below 800 - so i take its on the high side of normal. I filled it up right before I left to drive it back home after service. The idle is not jumping around and is stable. When cold the vibration is less noticeable. At operating temperature, I can feel the bottom of the seat vibrate
My 02 Boxster idles like a sewing machine even after over 260K miles. It is on its orignal coils too I might add.
My 03 Turbo idles less like a sewing machine. From a cold start the engine isn't rough runnning but it is a bit more snarly. For example the other day I heard small backfires through the exhaust which is a sign the engine's running a bit rich. Normal at cold start and done on purpose in fact to feed gasoline to the converters to get them warmed up guicker.
But after just a moment or two the backfiring went away.
Might add we've had our first cool weather since last spring and the engine started up from a colder temp than it has in months.
Once up to temp the Turbo engine smooths out but occasionally and I can't spot any reasons for this the engine runs a bit rougher than at other times.
Nothing scary and in fact how I notice this is happening is something in the cabin, a seat for instance, develops a mild vibration or a piece of interior trim buzzes barely at an audible level.
The engine doesn't in any way give me the impression it is sick or even feverish and there are no other symptoms.
Oil pressure, voltage gage readings are ok, too.
The coils are original in the Turbo which may play a role but save for two widely separated incidences of misfires -- both cases after the car sat out in either a heavy rainstorm or in real damp (foggy) weather overnight -- the engine has not manifested misfires at other times and the enigne now has almost 100K miles on it.
At plug change time the tech inspects the coils and so far has not recommended replacing them so I leave then in service.
So about all I do is note the slight roughness by way of the seat vibrating or piece of interior trim buzzing a bit and since this is not accompanied by any other signs of trouble pay it no more mind.
Sincerely,
Macster.
10-17-2012, 02:48 PM
#20
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My 02 Boxster idles like a sewing machine even after over 260K miles. It is on its orignal coils too I might add.
My 03 Turbo idles less like a sewing machine. From a cold start the engine isn't rough runnning but it is a bit more snarly. For example the other day I heard small backfires through the exhaust which is a sign the engine's running a bit rich. Normal at cold start and done on purpose in fact to feed gasoline to the converters to get them warmed up guicker.
But after just a moment or two the backfiring went away.
Might add we've had our first cool weather since last spring and the engine started up from a colder temp than it has in months.
Once up to temp the Turbo engine smooths out but occasionally and I can't spot any reasons for this the engine runs a bit rougher than at other times.
Nothing scary and in fact how I notice this is happening is something in the cabin, a seat for instance, develops a mild vibration or a piece of interior trim buzzes barely at an audible level.
The engine doesn't in any way give me the impression it is sick or even feverish and there are no other symptoms.
Oil pressure, voltage gage readings are ok, too.
The coils are original in the Turbo which may play a role but save for two widely separated incidences of misfires -- both cases after the car sat out in either a heavy rainstorm or in real damp (foggy) weather overnight -- the engine has not manifested misfires at other times and the enigne now has almost 100K miles on it.
At plug change time the tech inspects the coils and so far has not recommended replacing them so I leave then in service.
So about all I do is note the slight roughness by way of the seat vibrating or piece of interior trim buzzing a bit and since this is not accompanied by any other signs of trouble pay it no more mind.
Sincerely,
Macster.
My 03 Turbo idles less like a sewing machine. From a cold start the engine isn't rough runnning but it is a bit more snarly. For example the other day I heard small backfires through the exhaust which is a sign the engine's running a bit rich. Normal at cold start and done on purpose in fact to feed gasoline to the converters to get them warmed up guicker.
But after just a moment or two the backfiring went away.
Might add we've had our first cool weather since last spring and the engine started up from a colder temp than it has in months.
Once up to temp the Turbo engine smooths out but occasionally and I can't spot any reasons for this the engine runs a bit rougher than at other times.
Nothing scary and in fact how I notice this is happening is something in the cabin, a seat for instance, develops a mild vibration or a piece of interior trim buzzes barely at an audible level.
The engine doesn't in any way give me the impression it is sick or even feverish and there are no other symptoms.
Oil pressure, voltage gage readings are ok, too.
The coils are original in the Turbo which may play a role but save for two widely separated incidences of misfires -- both cases after the car sat out in either a heavy rainstorm or in real damp (foggy) weather overnight -- the engine has not manifested misfires at other times and the enigne now has almost 100K miles on it.
At plug change time the tech inspects the coils and so far has not recommended replacing them so I leave then in service.
So about all I do is note the slight roughness by way of the seat vibrating or piece of interior trim buzzing a bit and since this is not accompanied by any other signs of trouble pay it no more mind.
Sincerely,
Macster.
09-02-2013, 09:52 PM
#21
2005 911 S 997
Just bought my second porsche, first 911 with 24.5K miles (a few days ago) and it too vibrates at idle. I also drove an 06 911 S and it too had that idle vibration. Its part of the 911's charm 
09-03-2013, 12:02 PM
#22
Rennlist Member
excessive vibration is one issue by itself and an overall vibration caused by 'rough' idle when engine is fluctuating RPMs too much and shakes due to that is the different issue.
my motor now runs with max of 10 rpm fluctuation at idle and vibration is minimal, but it exists.
to get it that smooth you need to make sure all coils are new/good, O2 sensors are good, MAF sensor is good and use semi-solid engine mounts to prevent motor from traveling around.
If your RPMs are stable (use any odb2 scanner to look it up) but there is still vibration there - check with mechanic to see if flywheel is ok and no other issues exist.
my motor now runs with max of 10 rpm fluctuation at idle and vibration is minimal, but it exists.
to get it that smooth you need to make sure all coils are new/good, O2 sensors are good, MAF sensor is good and use semi-solid engine mounts to prevent motor from traveling around.
If your RPMs are stable (use any odb2 scanner to look it up) but there is still vibration there - check with mechanic to see if flywheel is ok and no other issues exist.
09-03-2013, 05:08 PM
#23
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You have described my experience almost to the T of my 997 C2.
Bought it having just had a large service and the idle was rough and caused vibration through the seats (the passenger seat would vibrate slightly when no one was in it). The shop pluged in the OBDII and determined that all values were within range, I was stumped.
I later had to change the coils but it still vibrated in the same way. I then did the semi-solid mounts and that made a slight improvement. From there on when I drove it I ran it really hard and that cleared it up so I can surmise that something was probably gunked up.
This isn't to say that this is your issue or that it was even the solution to mine but the idle you are describing is not normal.
Bought it having just had a large service and the idle was rough and caused vibration through the seats (the passenger seat would vibrate slightly when no one was in it). The shop pluged in the OBDII and determined that all values were within range, I was stumped.
I later had to change the coils but it still vibrated in the same way. I then did the semi-solid mounts and that made a slight improvement. From there on when I drove it I ran it really hard and that cleared it up so I can surmise that something was probably gunked up.
This isn't to say that this is your issue or that it was even the solution to mine but the idle you are describing is not normal.
09-03-2013, 06:18 PM
#24
You have described my experience almost to the T of my 997 C2.
Bought it having just had a large service and the idle was rough and caused vibration through the seats (the passenger seat would vibrate slightly when no one was in it). The shop pluged in the OBDII and determined that all values were within range, I was stumped.
I later had to change the coils but it still vibrated in the same way. I then did the semi-solid mounts and that made a slight improvement. From there on when I drove it I ran it really hard and that cleared it up so I can surmise that something was probably gunked up.
This isn't to say that this is your issue or that it was even the solution to mine but the idle you are describing is not normal.
Bought it having just had a large service and the idle was rough and caused vibration through the seats (the passenger seat would vibrate slightly when no one was in it). The shop pluged in the OBDII and determined that all values were within range, I was stumped.
I later had to change the coils but it still vibrated in the same way. I then did the semi-solid mounts and that made a slight improvement. From there on when I drove it I ran it really hard and that cleared it up so I can surmise that something was probably gunked up.
This isn't to say that this is your issue or that it was even the solution to mine but the idle you are describing is not normal.
So with your 911 - your seat is perfectly still when the idle falls to 800?
I ask because every 911 I have driven to date (997s) have had that slight vibration to the seat when not occupied. Thanks for sharing.
09-03-2013, 06:28 PM
#25
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I didnt think to look once I stopped feeling it in my seat.
I used to work at a dealer that sold late model ferrari/lamborghini/porsche so I was around them enough to know what was normal. If my understanding of his problem is correct then it was the same as mine which was not normal.
I would first clean the throttle body and MAF to see if that helps.
I used to work at a dealer that sold late model ferrari/lamborghini/porsche so I was around them enough to know what was normal. If my understanding of his problem is correct then it was the same as mine which was not normal.
I would first clean the throttle body and MAF to see if that helps.
