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

Reply
 
LinkBack Thread Tools Display Modes
Old 10-17-2010, 05:08 PM   #1
Registered User
 
Join Date: Mar 2008
Location: near Chicago
Posts: 523
Oh crap. What should I do?

Today I was at Road America for a track day. MVP Track Time does a great job, and puts on a great event. It's well run and the instructors (at least the one I was with) are very good.

However, on my third session, coming out of turn 13, I noticed a vibration. I immediately backed out of the throttle partially just to get around the last corner to the pits. I didn't hear any weird noises. When I got into pit lane, I up shifted so I was running at lower RPM, and the vibration went away. So I drove back to the paddock keeping the revs fairly low. I let the car cool. After a while I took the car for a drive outside the venue. Across the street was a country road, and I headed down it. I played with speeds and there was no vibration up to 50mph. Then I turned around and played with RPM. Above about 4000 rpm, the engine felt rough, and gets worse at higher RPM (only went to about 5k). Because it felt very consistent and even, it feels like a vibration. Again, as long as I kept the RPM low, the engine felt fine.

So I packed my stuff up, crossed my fingers and started my 2.5 hours home. Luckily, the drive is almost all highway, so I just kept the revs below about 3500 and drove it. I got home with no problems, and by that time I was thinking that maybe I had imagined the problem, or that it was something other than the engine. I needed gas, so I stopped close to home, and on the way home from the gas station, I drove it up into the 4000 rpm range in 1st gear (slow speed). Yup. Same problem.

When I was driving the track, I noticed a vibration in the car a couple of times before this. In a hard turn that I got into a bit hot, I would get a bit of under steer and felt a vibration that I'm pretty sure was from the front tires. When I had the problem, I initially thought it was the same thing, but it didn't go away when I got going straight again. I've been racking my brains over this, and I'm pretty sure it was a different feeling vibration, but I could be wrong.

No fluid leaks, no funny noises. It really just kind of feels like at higher RPM the engine starts running on 5 cylinders or something. It feels like it's running rough, but it's a completely regular, consistent roughness. It's not something where it runs lumpy or anything. It's not like the mixture is out of whack and the car is just running crappy.

So now I don't know what to do. I'm thinking about changing the oil and maybe getting an analysis (unless I obviously find metal particles, then I know it's an internal failure). I don't know if I should take it to my Porsche shop (Fischer Motors) or what. What do you guys think I should do to ID the problem?
Mike_Yi is offline   Reply With Quote
Old 10-17-2010, 06:10 PM   #2
Porscheectomy
 
Join Date: Mar 2006
Location: Seattle Area
Posts: 3,011
Could be a spark plug or coil, it could also be that you lost a wheel weight. Does the vibration come with a loss of power?
blue2000s is offline   Reply With Quote
Old 10-17-2010, 06:42 PM   #3
Registered User
 
KevinH1990's Avatar
 
Join Date: Feb 2006
Location: Virginia
Posts: 1,363
I'm pretty sure that your check engine light would illuminate if you lost a coil pack or a spark plug. I had a CEL illuminate when one of my coils went bad.

I don't think it is a wheel weight. The vibration from a wheel weight would be dependent on the car speed, not the engine speed.
__________________
2000 Arctic Silver/Black, Hard Top, On Board Computer
PNP Rear Speakers, HAES 6-channel amp, Avic Z140BH,
Painted Bumperettes, 2004 (OEM) Top and Frame
Homelink transmitter integrated in dash with Targa switch
Carrera Gauge Cluster with silver gauge faces, heated seats, litronics, painted console
KevinH1990 is offline   Reply With Quote
Old 10-17-2010, 07:26 PM   #4
Engine Surgeon
 
Join Date: Aug 2008
Location: Cleveland GA USA
Posts: 2,424
Its not internal. If it was you would have scattered the engine on the 2.5 hr trip home..

Probably a coil pack died or came unplugged and no the CEL won't illuminate in some of these instances. You also could have fouled a spark plug..

Wheel weights come into play when high wheel speeds are high, so if the issue happens in first gear above 4K RPM you can bet its not a wheel weight.
__________________
Jake Raby/www.flat6innovations.com
IMS Solution/ Faultless Tool Inventor
US Patent 8,992,089 &
US Patent 9,416,697
Developer of The IMS Retrofit Procedure- M96/ M97 Specialist
Jake Raby is offline   Reply With Quote
Old 10-18-2010, 02:42 AM   #5
Registered User
 
Join Date: Feb 2009
Location: Buffalo NY
Posts: 828
IMO, a wheel weight can play havoc at any speed depending on a myriad of factors including how heavy said weight is. The key is a lost wheel weight may be dependent on a particular speed to experience but will not be intermittent in nature in respect to repeatability.
eightsandaces is offline   Reply With Quote
Old 10-18-2010, 05:23 AM   #6
Registered User
 
Join Date: Mar 2008
Location: near Chicago
Posts: 523
Thanks for the input guys. It is definitely not speed related, but it is definitely rpm related. A coil pack makes sense. The engine does really feel like one cylinder isn't firing at all above 4k rpm. I think a plug wire would be intermittent. I'm going to pull the plugs today and see if any have a different look to them or smell of unburnt fuel. I may do a spark test on them too.

Thanks again for the input. I'm glad Jake thinks it's not internal.

Last edited by Mike_Yi; 10-18-2010 at 06:48 AM.
Mike_Yi is offline   Reply With Quote
Old 10-18-2010, 05:45 AM   #7
Registered User
 
Join Date: Mar 2007
Location: Ohio
Posts: 1,591
C'mon, Mike...is it speed related or not??
Frodo is offline   Reply With Quote
Old 10-18-2010, 06:48 AM   #8
Registered User
 
Join Date: Mar 2008
Location: near Chicago
Posts: 523
Quote:
Originally Posted by Frodo
C'mon, Mike...is it speed related or not??


Fixed.
Mike_Yi is offline   Reply With Quote
Old 10-18-2010, 07:25 AM   #9
Registered User
 
Join Date: Jan 2007
Location: BC
Posts: 1,260
Quote:
Originally Posted by Mike_Yi


Fixed.
So... what was the fix?
__________________
2001 Boxster, 5 spd, Seal Grey
clickman is offline   Reply With Quote
Old 10-18-2010, 08:06 AM   #10
Registered User
 
Join Date: Mar 2007
Location: Ohio
Posts: 1,591
Quote:
Originally Posted by clickman
So... what was the fix?
Read his 9:23 post (which used to say, in part: "It is definitely not speed related, but it is definitely speed related.") and my 9:45 post. That was the "fix". (Far as I know, the car still needs work.)
Frodo is offline   Reply With Quote
Old 10-18-2010, 10:35 AM   #11
Registered User
 
tonycarreon's Avatar
 
Join Date: May 2009
Location: Frederick, MD
Posts: 1,396
have you ruled out the engine mount?
__________________
"Speed has never killed anyone, suddenly becoming stationary... that's what gets you."
tonycarreon is offline   Reply With Quote
Old 10-18-2010, 04:32 PM   #12
Registered User
 
Join Date: Mar 2008
Location: near Chicago
Posts: 523
Quote:
Originally Posted by tonycarreon
have you ruled out the engine mount?

Well, I kinda did automatically because it didn't seem related to torque. If it were an engine mount, I'd think that torque would cause the engine to rotate (equal and opposite to crank rotation) regardless of rpm. The rotation of the engine would cause some kind of vibration-type feeling.

Last edited by Mike_Yi; 10-18-2010 at 10:50 PM.
Mike_Yi is offline   Reply With Quote
Old 10-21-2010, 07:05 AM   #13
Registered User
 
Join Date: Mar 2008
Location: near Chicago
Posts: 523
Does anybody have any suggestion on how I can troubleshoot the problem and identify what's causing it?
Mike_Yi is offline   Reply With Quote
Old 10-21-2010, 07:33 AM   #14
Engine Surgeon
 
Join Date: Aug 2008
Location: Cleveland GA USA
Posts: 2,424
do you have a durametric unit??
__________________
Jake Raby/www.flat6innovations.com
IMS Solution/ Faultless Tool Inventor
US Patent 8,992,089 &
US Patent 9,416,697
Developer of The IMS Retrofit Procedure- M96/ M97 Specialist
Jake Raby is offline   Reply With Quote
Old 10-21-2010, 09:09 AM   #15
Registered User
 
Join Date: Mar 2008
Location: near Chicago
Posts: 523
Nope. Wish I did though.
Mike_Yi is offline   Reply With Quote
Old 10-21-2010, 10:36 AM   #16
Registered User
 
texomawaves's Avatar
 
Join Date: Sep 2009
Location: Tx
Posts: 249
Here's what I did recently... I bought the Durametric, and showed Cyl misfire #5. So... I swapped coil pack between cyl 5 and 6 and guess what??? The next CEL code threw a Cyl misfire in number 6. Bingo!!!

So...

1. read your code on the Durametric
2. swap coil packs on adjacent cyl AND...
3. swap plugs on OTHER adjacent cyl
4. clear the Durametric code
5. drive car, run engine up to the 4k+ RPM
6. let engine cool, drink a beer (or two)
7. read the code again and see which cyl the problem follows
8. order parts
9. take girlfriend out to dinner

This procedure took me an hour or so. I'm assuming you have ignition issue, and guessing a fouled plug. My coil pack issue wasn't rpm related, it was intermittent. I hope this helps.

__________________
Chris Dennis, Plano, Texas

'07 Boxster, arctic silver, 2.7, Tiptronic, 51k miles, and no mods!
texomawaves is offline   Reply With Quote
Old 10-21-2010, 10:46 AM   #17
Registered User
 
Join Date: Apr 2010
Location: Wichita; KS
Posts: 144
I owned my NB for about two years before I bought Vag-com. Durametric will be one of the first tools that I buy most likely before I buy my 986. Most certainly if it tells me that rev history on the engine.
__________________
2000 New Beetle / in search of 03 986S triple black
Caractere kit seam sealed, Caractere rear wing, 1 3/4" drop on coilovers, 235/40/18 Kuhmo XS on 18x8 Millie Miglia Spider II's, H2sport spindles, H&R front Sway bar, O-bar rear torsion, VF Eng. motor mounts, G60 12# flywheel, Nuespeed P-flow intake, Forge DV, Samco IP, Custom K04 turbo and Upsolute chip, 4 bar fpr, TT 2 1/2" SS DP, 2 1/2" custom stainless exhaust no muffler, Peleguin LSD, B&M SS, Momo 14" wheel, R32 steering rack.
yelojkt is offline   Reply With Quote
Old 10-21-2010, 10:52 AM   #18
Track rat
 
Topless's Avatar
 
Join Date: Nov 2006
Location: Cucamonga CA
Posts: 3,643
Garage
"Does anybody have any suggestion on how I can troubleshoot the problem and identify what's causing it?"


Jack up your car, pull the spark plugs and inspect the plugs and coil paks. The misfire cyl spark plug tip will be discolored (usually black or wet) compared with the other 5. Inspect the coil pak on the offending cyl and look for cracks or signs of arcing. Replace failed parts. Easy breezy.

The Durametric is nice but any simple $60 OBDII reader will also give you misfire codes that identify which cyl. is the problem.
__________________
2009 Cayman 2.9L PDK (with a few tweaks)
PCA-GPX Chief Driving Instructor

Last edited by Topless; 10-21-2010 at 10:54 AM.
Topless is offline   Reply With Quote
Old 10-21-2010, 11:01 AM   #19
Registered User
 
texomawaves's Avatar
 
Join Date: Sep 2009
Location: Tx
Posts: 249
One simple thing I forgot to mention... stop by Autozone and get them to read your code with their Actron. Not as detailed as a Durametric, and dont think it can clear codes, BUT you might get an early indication while you're waiting on your $300 Durametric to arrive in the mailbox
__________________
Chris Dennis, Plano, Texas

'07 Boxster, arctic silver, 2.7, Tiptronic, 51k miles, and no mods!
texomawaves is offline   Reply With Quote
Old 10-21-2010, 11:45 AM   #20
Registered User
 
Join Date: Mar 2008
Location: near Chicago
Posts: 523
I don't have a CEL so AFAIK, I won't have a code.

I do have an AutoTap, which is supposed to work on all poast-'98 cars. So that should give me diag info. I'll try it this weekend.
Mike_Yi 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 08:32 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