Strange PPI Results - Dorkiphus.net

Porsche Technical Discussions Porsche related technical discussions and questions go here.

Reply
 
Thread Tools Display Modes
  #1  
Old 01-17-2019, 09:16 AM
N Fotouhi's Avatar
N Fotouhi N Fotouhi is offline
 
Join Date: Feb 2006
Location: NJ
Posts: 2,399
N Fotouhi
Default Strange PPI Results

This is on 2004 GT3 with 45K miles and 0 range 2 Over revs which would indicate missed shift. It is 2 owner car, and owned by the current owner since 2008 (about 17K miles), and has been primarily a track car, and in a very desirable condition with fresh suspension, and many services up to date. I am not willing to walk away from the car yet, but the fact that one entire side seems to show "something" is very strange.

All cylinders have very minor scoring.
Compression test: Cyl. 1 = 151 , 2 = 150 , 3 = 150, 4 =
145 , 5 = 145 , 6 =146 .
Leakdown test: Cyl. 1 = 4% , 2 = 5% , 3 = 5% , 4 = 19%
, 5 = 20% , 6 = 19%.
Check cam shaft deviation via tester. Bank 1 at -1.3.
Bank 2 at -3.73.

Additional usual checks to check for leaking valves and rings have shown no evidence of leak from either side.

I have asked for hot leak down and waiting to hear.

Any thoughts, ideas, or speculations?

Nader
__________________
Nader

There are 3 sides to every story. Mine, yours, and the truth.

91 944 S2 - Mine, Sold
7? 914-6 Vintage racer - Mine
93 964 - Not mine
95 993 - Hers - Sold and will be missed
04 GT3 - ours? Doing double duties at DE, anyway
06 987 - Hers - plan to let son use for DE - My DIY
A few others

Last edited by N Fotouhi; 01-17-2019 at 09:18 AM. Reason: Added more information
Reply With Quote
  #2  
Old 01-17-2019, 10:09 AM
Roo's Avatar
Roo Roo is offline
 
Join Date: Aug 2011
Location: Sterling, VA
Posts: 467
Roo
Default

Well, if the rings and valves aren't leaking, the No 2 Bank cylinder numbers would suggest a head gasket leak.
Has an oil analysis and coolant analysis been performed?

Quote:
Originally Posted by N Fotouhi View Post
This is on 2004 GT3 with 45K miles and 0 range 2 Over revs which would indicate missed shift. It is 2 owner car, and owned by the current owner since 2008 (about 17K miles), and has been primarily a track car, and in a very desirable condition with fresh suspension, and many services up to date. I am not willing to walk away from the car yet, but the fact that one entire side seems to show "something" is very strange.

All cylinders have very minor scoring.
Compression test: Cyl. 1 = 151 , 2 = 150 , 3 = 150, 4 =
145 , 5 = 145 , 6 =146 .
Leakdown test: Cyl. 1 = 4% , 2 = 5% , 3 = 5% , 4 = 19%
, 5 = 20% , 6 = 19%.
Check cam shaft deviation via tester. Bank 1 at -1.3.
Bank 2 at -3.73.

Additional usual checks to check for leaking valves and rings have shown no evidence of leak from either side.

I have asked for hot leak down and waiting to hear.

Any thoughts, ideas, or speculations?

Nader
__________________
CT

83 911SC
12 Lexus CT 200h
08 Outback wagon
04 F250 SD

Truth be it known, I just like working on cars - Slick Henderson
Reply With Quote
  #3  
Old 01-17-2019, 10:35 AM
cmartin's Avatar
cmartin cmartin is offline
 
Join Date: Sep 2003
Location: Pasadena, MD
Posts: 7,577
cmartin
Default

Quote:
Additional usual checks to check for leaking valves and rings have shown no evidence of leak from either side.
What does this mean? When the leaks were detected there was nothing detected from intake or exhaust?

Quote:
Well, if the rings and valves aren't leaking, the No 2 Bank cylinder numbers would suggest a head gasket leak.
Seems to make sense, I'd want to check fluids.
__________________
78 SC, the 'Red Car'
Reply With Quote
  #4  
Old 01-17-2019, 12:27 PM
Vicegrip's Avatar
Vicegrip Vicegrip is offline
Porkchop & SGB for prez!
 
Join Date: Jan 2003
Location: The other Woodstock.
Posts: 13,238
Vicegrip has seven HoF threadsVicegrip has seven HoF threadsVicegrip has seven HoF threadsVicegrip has seven HoF threadsVicegrip has seven HoF threadsVicegrip has seven HoF threads
Default

A leak down shows more than a %. You can often tell where the air is going. Did they indicate where?
__________________
http://vimeo.com/29896988

“Those that can make you believe in absurdities can make you commit atrocities.” Voltaire.

"There is grandeur in this view of life...." Darwin.

The mountains are calling and I must go.

“The earth has music for those who listen”
Shakespeare.

You Matter.
(Until you multiply yourself times the speed of light squared. Then you Energy)

“We’ve got lots of theories, we just don’t have the evidence’.
Reply With Quote
  #5  
Old 01-17-2019, 01:35 PM
N Fotouhi's Avatar
N Fotouhi N Fotouhi is offline
 
Join Date: Feb 2006
Location: NJ
Posts: 2,399
N Fotouhi
Default

The hot leakdown shows no difference.

After some checking and discussion, the hypothesis is that the differences may be an indication of differences in manufacturing tolerances between the two sides since there seems to be no mechanical indication.

I am also told by a reputable source that it is not unusual to see such differences in varioram engines.

If I buy and it blows up, I made the wrong call. Otherwise, it was nothing to worry about.
__________________
Nader

There are 3 sides to every story. Mine, yours, and the truth.

91 944 S2 - Mine, Sold
7? 914-6 Vintage racer - Mine
93 964 - Not mine
95 993 - Hers - Sold and will be missed
04 GT3 - ours? Doing double duties at DE, anyway
06 987 - Hers - plan to let son use for DE - My DIY
A few others
Reply With Quote
  #6  
Old 01-17-2019, 04:45 PM
smdubovsky's Avatar
smdubovsky smdubovsky is offline
 
Join Date: Mar 2004
Location: Silver Spring, MD
Posts: 5,281
smdubovsky has three HoF threadssmdubovsky has three HoF threadssmdubovsky has three HoF threads
Default

Thats a lot of leakdown deviation. Where was the air coming out? You can typically hear: Intake/case/exhaust.


Are they really on the compression stroke doing the 4/5/6 bank? (shop error?)
__________________
Stephen
www.salazar-racing.com
1970 914/6 - 3.0L GT
1983 911SC - 3.32L IROC
1984 930
2008 S2R1000, dirt bikes (some gas, some electric), Sherco trials bike
Sold: 2001 Boxster (hers), 2003 996tt x50 , SpecE30, 1996 E36M3 GTS2 racecar, 2015 Mustang GT
Reply With Quote
  #7  
Old 01-17-2019, 05:19 PM
Vicegrip's Avatar
Vicegrip Vicegrip is offline
Porkchop & SGB for prez!
 
Join Date: Jan 2003
Location: The other Woodstock.
Posts: 13,238
Vicegrip has seven HoF threadsVicegrip has seven HoF threadsVicegrip has seven HoF threadsVicegrip has seven HoF threadsVicegrip has seven HoF threadsVicegrip has seven HoF threads
Default

Quote:
Originally Posted by smdubovsky View Post
Thats a lot of leakdown deviation. Where was the air coming out? You can typically hear: Intake/case/exhaust.


Are they really on the compression stroke doing the 4/5/6 bank? (shop error?)
^!
__________________
http://vimeo.com/29896988

“Those that can make you believe in absurdities can make you commit atrocities.” Voltaire.

"There is grandeur in this view of life...." Darwin.

The mountains are calling and I must go.

“The earth has music for those who listen”
Shakespeare.

You Matter.
(Until you multiply yourself times the speed of light squared. Then you Energy)

“We’ve got lots of theories, we just don’t have the evidence’.
Reply With Quote
  #8  
Old 01-17-2019, 08:00 PM
N Fotouhi's Avatar
N Fotouhi N Fotouhi is offline
 
Join Date: Feb 2006
Location: NJ
Posts: 2,399
N Fotouhi
Default

Quote:
Originally Posted by smdubovsky View Post
Thats a lot of leakdown deviation. Where was the air coming out? You can typically hear: Intake/case/exhaust.


Are they really on the compression stroke doing the 4/5/6 bank? (shop error?)
Does compression stroke mean TDC?

I have no reason to think that the shop made an error since everything was rechecked over 3 days. There was no indication of leak from intake/case/exhaust. That is why the results are puzzling, and I have finally decided it may not indicate an issue.
__________________
Nader

There are 3 sides to every story. Mine, yours, and the truth.

91 944 S2 - Mine, Sold
7? 914-6 Vintage racer - Mine
93 964 - Not mine
95 993 - Hers - Sold and will be missed
04 GT3 - ours? Doing double duties at DE, anyway
06 987 - Hers - plan to let son use for DE - My DIY
A few others
Reply With Quote
  #9  
Old 01-17-2019, 08:20 PM
Vicegrip's Avatar
Vicegrip Vicegrip is offline
Porkchop & SGB for prez!
 
Join Date: Jan 2003
Location: The other Woodstock.
Posts: 13,238
Vicegrip has seven HoF threadsVicegrip has seven HoF threadsVicegrip has seven HoF threadsVicegrip has seven HoF threadsVicegrip has seven HoF threadsVicegrip has seven HoF threads
Default

Quote:
Originally Posted by N Fotouhi View Post
Does compression stroke mean TDC?

I have no reason to think that the shop made an error since everything was rechecked over 3 days. There was no indication of leak from intake/case/exhaust. That is why the results are puzzling, and I have finally decided it may not indicate an issue.
Same procedure different day same result = no issue.
__________________
http://vimeo.com/29896988

“Those that can make you believe in absurdities can make you commit atrocities.” Voltaire.

"There is grandeur in this view of life...." Darwin.

The mountains are calling and I must go.

“The earth has music for those who listen”
Shakespeare.

You Matter.
(Until you multiply yourself times the speed of light squared. Then you Energy)

“We’ve got lots of theories, we just don’t have the evidence’.
Reply With Quote
  #10  
Old 01-17-2019, 10:02 PM
Dr K's Avatar
Dr K Dr K is offline
Colorado's finest
 
Join Date: Apr 2005
Location: Montgomery County, MD
Posts: 16,150
Dr K has two HoF threadsDr K has two HoF threads
Default

The air has to be going somewhere if it's leaving he cylinder. Did they listen? Where is the car located - perhaps a different shop... Mezger engine is supposed to be a tank--should tolerate a rebuild well but make sure the car is priced to allow for that (or mitigate the risk).
__________________
Peter (not "Pete") K.

2016 Cayman S
1999 Miata ("SM") race car
2016 Toyota Highlander--tow vehicle/wife's DD
2017 VW GTI SE (DD)

Gone and missed:
1992 Miata ("SSM") race car
2009 911 C2S Coupe
2004 Toyota Prius - sold to son's girlfriend
2006 Dodge Durango
2003 Acura MDX
86 Black 911 Coupe race car
86 Gold 911 Targa
82 WineRedMetallic 911 Targa
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 Off

Forum Jump