Go Back   986 Forum - for Porsche Boxster & Cayman Owners > Porsche Boxster & Cayman Forums > Boxster General Discussions

Reply
 
LinkBack Thread Tools Display Modes
Old 01-02-2018, 02:06 PM   #1
Registered User
 
Join Date: Sep 2015
Location: St. Petersburg, Florida
Posts: 222
Need Help with Strange Vibration

Trying to help a computer illiterate buddy of mine with his '00 Boxster. He's been telling me about a vibration that comes and goes, and I was beginning to think he was sniffing glue until the other day when I was in the car with him. Sitting at a light, he said "there it is, there it is," and I can say is that it was certainly noticeable.

It's a base car with tip, less than 60K miles. IMS was done around 2 years ago. It was idling perfectly at a light, and then what I would call a cyclical vibration started. No change in RPM's, no CEL, nothing, just a strong, cyclical vibration that you can almost hear, but definitely feel. Leaving the light, the car ran perfectly.

Any clue what this might be?
__________________
1998 Porsche Boxster - Ocean Jade Metallic

1985 Porsche Carrera Targa - Guards Red

1978 Porsche 911SC Euro Non-Sunroof - Grand Prix White
Seadweller is offline   Reply With Quote
Old 01-02-2018, 03:31 PM   #2
Registered User
 
Join Date: Sep 2008
Location: Florida
Posts: 2,068
motor mount.

Back in 2011, I bought a 98 base that needed some love. One item of note was a bit of a rough idle. After changing plugs and filters, along with cleaning the MAF, I felt no difference. One day while at a light, I noticed that although I still had a rough idle, the tach was rock steady. I replaced the mount and the car felt like new. Worth a shot as I'll bet your buddy may have not yet replaced his yet.
dghii is offline   Reply With Quote
Old 01-02-2018, 04:40 PM   #3
Registered User
 
Join Date: Feb 2017
Location: CO
Posts: 938
Yep, as above. Absolutely no doubt the motor mount is shot in the car. Relatively inexpensive repair. Not too tough to do DYI but takes some knowledge and a couple of semi-special tools makes it a little easier. A lift is helpful too.
Geof3 is offline   Reply With Quote
Old 01-03-2018, 06:27 AM   #4
Registered User
 
Join Date: Sep 2015
Location: St. Petersburg, Florida
Posts: 222
Thanks guys...What puzzled me is that the vibration isn't there 100% of the time. I've been in the car several times trying to replicate it, and it never appeared, which is why I questioned him to begin with. This time, I was in the car with him for over an hour, and for nearly the entire time, there was no vibration at all. I was about to refer him to a psychiatrist, when the vibration just appeared out of nowhere while sitting at a light.

Would a bad motor mount cause an intermittent issue like this, or would the vibration be present 100% of the time?
__________________
1998 Porsche Boxster - Ocean Jade Metallic

1985 Porsche Carrera Targa - Guards Red

1978 Porsche 911SC Euro Non-Sunroof - Grand Prix White
Seadweller is offline   Reply With Quote
Old 01-03-2018, 10:28 AM   #5
98 Arctic silver 986
 
tommy583's Avatar
 
Join Date: Jul 2011
Location: Upstate, NY
Posts: 1,225
Garage
If you notice the RPM isn't steady when the vibration happens, try cleaning the idle control valve. It is on the side of the throttle body. But as I reread your post it appears the RPM's were steady, so I will third the motor mount.
tommy583 is offline   Reply With Quote
Old 01-04-2018, 09:41 PM   #6
Registered User
 
Join Date: Jun 2017
Location: Visalia, Ca
Posts: 135
Need Help with Strange Vibration

Quote:
Originally Posted by Seadweller View Post
Thanks guys...What puzzled me is that the vibration isn't there 100% of the time. I've been in the car several times trying to replicate it, and it never appeared, which is why I questioned him to begin with. This time, I was in the car with him for over an hour, and for nearly the entire time, there was no vibration at all. I was about to refer him to a psychiatrist, when the vibration just appeared out of nowhere while sitting at a light.

Would a bad motor mount cause an intermittent issue like this, or would the vibration be present 100% of the time?
This sounds more like a fuel issue to me. Sitting at a stop, there is no suspension or road issue at hand. So, odd vibrations are motor related. This leads me to poor fuel quality. Could be a knock sensor timing issue.
__________________
2001 Boxster S, Metallic Black, 6 Speed Manual, 3.2 liter engine.
RobertKing is offline   Reply With Quote
Old 01-04-2018, 10:09 PM   #7
Registered User
 
Join Date: Feb 2017
Location: CO
Posts: 938
Quote:
Originally Posted by Seadweller View Post
Thanks guys...What puzzled me is that the vibration isn't there 100% of the time. I've been in the car several times trying to replicate it, and it never appeared, which is why I questioned him to begin with. This time, I was in the car with him for over an hour, and for nearly the entire time, there was no vibration at all. I was about to refer him to a psychiatrist, when the vibration just appeared out of nowhere while sitting at a light.

Would a bad motor mount cause an intermittent issue like this, or would the vibration be present 100% of the time?
Depends, if the MM is shot (I promise you it is with that mileage if itís original) itís possible that another issue causing a vibration is felt more. So no, most likely an intermittent vibe isnít going to be caused by the MM but a dead MM can potentially be felt for sure at idle. Especially if the center rubber has completely detached, which is very common. Basically the front of the engine is sitting low, and on a slightly damped chunk of metal.
Geof3 is offline   Reply With Quote
Old 01-05-2018, 06:41 AM   #8
Registered User
 
Join Date: Sep 2015
Location: St. Petersburg, Florida
Posts: 222
I'm wondering if perhaps the motor mount is just worn to the point that the motor might shift a bit to metal on metal contact on occasion, causing the vibration to be pronounced. When leaving the light, it shifts again, perhaps back into normal position on the rubber portion, which eliminates the vibration.

Any idea how many hours it takes to replace it?
__________________
1998 Porsche Boxster - Ocean Jade Metallic

1985 Porsche Carrera Targa - Guards Red

1978 Porsche 911SC Euro Non-Sunroof - Grand Prix White
Seadweller is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -8. The time now is 12:24 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2019, vBulletin Solutions, Inc.
Content Relevant URLs by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Pelican Parts Website -    DMCA Registered Agent Contact Page