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SoyRacer
Joined: 25 May 2003
Posts: 156
Location: Long Island, New York
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 Posted: Fri Sep 09, 2005 5:45 am Post subject: Miss In Cylinder #4 -- -- Help? |
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Okay, Before I Go And Rip The Head Off:
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Cylinder #4 Has A Miss. Compression Even All Around, New Plugs And Cap, No Vac. Leaks, Injectors Have Even Pressure And All Have Even Spray Pattern.
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What Is The Possibility That I Have A Broken Valve Spring And If So Can I Replace It Without Removing The Cylinder Head (Air In The Cylinder Trick)?
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I Guess What I'm Asking Is - Is There Anything I Have Missed?
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Thank You My 931 Guru Friends!!
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Smoothie
Joined: 01 Jan 2003
Posts: 8032
Location: DE (the one near MD, PA, NJ)
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| Posted: Fri Sep 09, 2005 6:36 am Post subject: |
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Check it with a vacuum gauge. A broken spring should give you a reading
like #5 here - http://www.centuryperformance.com/vacuum.asp
or #13 here - http://www.earlycuda.org/tech/vacuum2.htm
Yes, springs can be replaced without removing the head. There are some past topics floating around somewhere out there on what's needed.
_________________
"..it's made in Germany. You know the Germans always make good stuff."
'82 924T, US version, dark green metallic, 5 speed Audi 016G gearbox |
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dpw928
Joined: 02 Nov 2002
Posts: 1860
Location: owasso, ok 74055
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| Posted: Fri Sep 09, 2005 10:48 am Post subject: |
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Sparkplug wires?
Dennis
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81 931 5 sp
78 928 5 sp Silver
78 928 AT Euro Black |
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Lizard
Joined: 03 Nov 2002
Posts: 9364
Location: Abbotsford BC. Canada
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| Posted: Fri Sep 09, 2005 11:08 am Post subject: |
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spark plug wires, or what brand/manufacture is your distributor cap? some of them tend to have a spark jump inside the cap.
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3 928s, |
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SoyRacer
Joined: 25 May 2003
Posts: 156
Location: Long Island, New York
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| Posted: Sat Sep 10, 2005 8:19 am Post subject: |
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| Lizard wrote: | | spark plug wires, or what brand/manufacture is your distributor cap? some of them tend to have a spark jump inside the cap. |
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Bosch Dist Cap - The Old One (Bosch Also) Was Fine But I Wanted To Eliminate It As A Possibility.
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The Beru Wires Are Fresh (One Year Old) And The Resistance Was Almost Dead Even On All Of Them. I'm Getting A New Set Of Bosch Wires Anyway Though.
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Any Other Ideas?
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Wasted Cam Lobes?
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I'm Opening Up The Valve Cover Tomorrow So Give Me Some Things To Look For.
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Thanks !
_________________
1973 911-RS 3.2 Track Car
1981 Porsche 931/Carrera GT Project
1981 Porsche 931 Euro W/CGT Intercooler
1984 Porsche 944 Gutted Track Car
1987 Porsche 924s Rally Style (sold 3-2012)
2000 Chevy C-2500 Pick-up
2004 Subaru Forester STi |
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endwrench
Joined: 07 Dec 2002
Posts: 1631
Location: Victor, Montana
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| Posted: Tue Sep 13, 2005 1:33 pm Post subject: |
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So, did you find a wasted exaust cam lobe? Sounds the most obvious and they are a bit notorious for it.
Todd |
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SoyRacer
Joined: 25 May 2003
Posts: 156
Location: Long Island, New York
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| Posted: Tue Sep 13, 2005 1:39 pm Post subject: |
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| dpw928 wrote: | Sparkplug wires?
Dennis |
Well, I Replaced The Spark Plug Wires And Strangely Enough I Did Find That The #3 Wire Was Pretty Corroded. That Didn't Fix The Miss Though.
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I Then Removed The Injectors And Cleaned Them Out With Acetone On Our Bench Fixture. I Believe #4 Was Clogged Because It Took Some Extra Pressure To Get The Same Pattern As The Other Three. Anyway, I Reassembled Everything With Fresh O-Rings, Copper Washers And Gaskets All Around And Fired Her Up. Woo Hoo !!! She Ran Great And I Never Even Had To Remove The Cam Cover.
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So Now I Can Make It To The Concours Event This Coming Sunday At Old Westbury Gardens And Claim My First Place Trophy  .
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Being An Exotic Car Mechanic By Trade I Have A Bad Habit Of Thinking "Worst Case Scenario" But It's Great When It Turns Out To Be Just A Basic Tune-Up And Fuel Injector Service.
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It's Funny, I Have No Reservation About Tearing Down And Rebuilding A Ferrari V12 Or Building A 700-HP 993 Twin Turbo Engine, But When It Comes To My Own Cars I Have A Genuine Fear Of Murphys Law Clobbering Me Over The Head. Go Figure !?
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Link To Tri-Mark Concours - http://www.metronypca.org/Concours/2005/great-marques/Great-marques-9-18.html
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_________________
1973 911-RS 3.2 Track Car
1981 Porsche 931/Carrera GT Project
1981 Porsche 931 Euro W/CGT Intercooler
1984 Porsche 944 Gutted Track Car
1987 Porsche 924s Rally Style (sold 3-2012)
2000 Chevy C-2500 Pick-up
2004 Subaru Forester STi |
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Vince Ponz
Joined: 02 Nov 2002
Posts: 3581
Location: Florida
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| Posted: Tue Sep 13, 2005 11:51 pm Post subject: |
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Now, Now Soyracer. Yeah you, the guy with the make believe 924 turbo. Hey guys they are both NAs. How do I know? I judge the cars at the Westbury Gardens every year.
Just kidding. Both cars are very, very nice. I do judge at the Gardens.
_________________
"Never let them see you sweat"
77.5 924 modified track car
79 931 Euro stock
88 924S SE
87 911 Targa stock |
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