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Automotive Monomaniac
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Question re "Overboost Switch"
My engine has been cutting out on hard right turns... and then it runs normally when I straighten the car out again.
![]() I think I may have found the problem. After poking around with a flashlight last night, I noticed the "overboost switch" wire had vibrated loose. The wire has a rubber housing, so it was kept in loose contact with the switch. I assume right turns pulled on the wire and it broke contact... and when I went straight contact was again made. My questions: Will the engine die if the overboost switch is disconnected? What does the overboost switch kill (fuel or ignition)?
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2012 - Porsche Boxster Spyder 6MT / 2018 - Porsche 911 Carrera 7MT / 2018 - Porsche Macan 7DCT / 2018 - Volkswagen GTI 6MT |
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Registered
Join Date: Nov 2007
Location: Calgary AB
Posts: 249
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I might stand to be corrected but I was having similar troubles which affected the fuel not the ignition, I had the switch replaced but the mechanic mentioned that you could just ground it to disable the switch however leaving your engine vunerable.
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Q 1991 RRC 1995 993 C2 2002 996TT 1984 930 Turbo (gone and missed) |
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Automotive Monomaniac
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Quote:
![]() You are saying the switch must be connected or grounded. If so, then I have found my engine cut-out problem. If the switch can be left completely disconnected and the engine still runs, I have to continue searching. You don't want to disable the switch.
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2012 - Porsche Boxster Spyder 6MT / 2018 - Porsche 911 Carrera 7MT / 2018 - Porsche Macan 7DCT / 2018 - Volkswagen GTI 6MT |
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Registered
Join Date: Nov 2007
Location: Calgary AB
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The Germans are efficient (being one of them) if you didnt need it, it wouldnt be there, my opinion. The last thing that I want or could afford is grenading my engine and having to replace it.
Off topic but how do you like your fabspeed? I just bolted up the single outlet with air intakes and a 1 bar spring...it should be on the street tonite
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Q 1991 RRC 1995 993 C2 2002 996TT 1984 930 Turbo (gone and missed) |
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resident samsquamch
Join Date: Oct 2005
Location: Cooterville, Cackalacky
Posts: 6,815
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Answers...
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-jeff back in the saddle: '95 993 - just another black C2 *SOLD*: '87 930 GP White - heroin would have been a cheaper addiction... "Ladies and Gentlemen, from Boston Massachusetts, we are Morphine, at your service..." - Mark Sandman (RIP ![]() |
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Registered
Join Date: Nov 2007
Location: Calgary AB
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Sandman,
Disconnect and disabled are two different thngs. Am I correct that if it is disabled the car will still be operational but vunerable to damage?
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Q 1991 RRC 1995 993 C2 2002 996TT 1984 930 Turbo (gone and missed) |
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resident samsquamch
Join Date: Oct 2005
Location: Cooterville, Cackalacky
Posts: 6,815
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The car is not operational, UNLESS you have grounded the wire that once connected the switch. The fuel pumps won't run. I know this because whenever I remove my 965 intercooler, which has the overboost switch on the actual intercooler, I can't run my fuel pumps (to check fuel pressures for example) unless I ground that wire.
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-jeff back in the saddle: '95 993 - just another black C2 *SOLD*: '87 930 GP White - heroin would have been a cheaper addiction... "Ladies and Gentlemen, from Boston Massachusetts, we are Morphine, at your service..." - Mark Sandman (RIP ![]() |
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Registered
Join Date: Nov 2007
Location: Calgary AB
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Gotcha, so i was correct...As Emission said I answered his questions but in a round about way.
Have patience I am new and trying to learn these cars!! Thanks
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Q 1991 RRC 1995 993 C2 2002 996TT 1984 930 Turbo (gone and missed) |
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resident samsquamch
Join Date: Oct 2005
Location: Cooterville, Cackalacky
Posts: 6,815
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As for actually disabling the switch, I think it's set to cut the fuel pumps at 1.2 bar (from what I recall...might be wrong about this number), and I've seen a few threads where people have tripped it. So I guess it can be thought of as a good safe gaurd. However, if it really is 1.2 bar, I'm not sure if the damage is already done???!!!
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-jeff back in the saddle: '95 993 - just another black C2 *SOLD*: '87 930 GP White - heroin would have been a cheaper addiction... "Ladies and Gentlemen, from Boston Massachusetts, we are Morphine, at your service..." - Mark Sandman (RIP ![]() |
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Registered
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running naked through a mine field...dont want to take the chance or find out.
I just had a 1bar spring installed. Pros and Cons??
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Q 1991 RRC 1995 993 C2 2002 996TT 1984 930 Turbo (gone and missed) |
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Automotive Monomaniac
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Quote:
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2012 - Porsche Boxster Spyder 6MT / 2018 - Porsche 911 Carrera 7MT / 2018 - Porsche Macan 7DCT / 2018 - Volkswagen GTI 6MT |
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Automotive Monomaniac
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Quote:
![]() - Mike
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Wayah Road Warrior
Join Date: Jun 2002
Location: Greenville, SC
Posts: 1,559
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There is another thread from a couple of days ago (Name this part ....)
Name this part and its function and win that was talking about the overboost relay. Is that the same as the switch? If not, do you have pics of the switch?
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02 996tt White 87 930 GP White (Sold) 87 911 Targa Guards Red(Sold) |
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Registered
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When I got my car the switch was disabled, grounded to the same connection on the intercoler as the intercooler ground. My wastegate had 1.1 bar worth of springs in it, so I am guessing that the previsous owner got tired of the fuel pumps shutting down.
I went down to .8 bar in the wastegate, and continued to have problems with the overboost. I even installed a new switch. I hate the location that it is in with regards to the 965 intercooler. I agree with teh folks that have moved their switch closer to the intake. Since I have had off and on issues with mine, I may do this as well. Bill |
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resident samsquamch
Join Date: Oct 2005
Location: Cooterville, Cackalacky
Posts: 6,815
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I have a .80 bar spring in my Tial, and I have the mods to rock a 1.0 bar spring, but...
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-jeff back in the saddle: '95 993 - just another black C2 *SOLD*: '87 930 GP White - heroin would have been a cheaper addiction... "Ladies and Gentlemen, from Boston Massachusetts, we are Morphine, at your service..." - Mark Sandman (RIP ![]() |
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Registered
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I am with you 100% sand_man. Not to mention when I had all the springs in the Tial, the car was REALLY fast, and I am sure I would have lost my drivers lic.
Bill |
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Automotive Monomaniac
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I took out my 1.0 bar spring and put the .8 bar spring back in...
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A fellow Pelacanite
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Depends on what turbo, IC and fuel you are running.
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1981 UK 930. G50/01 shortened, 964 3.8RS Fibreglass Body Kit, 18" Alloys 8.5" F & 10" R, 225's F & 285's R, Special Colour Metallic Blue Paint, FIA Sparco Evo's, A/C and Air Pump removed, Electronic Boost Controller, GHL Headers, Tial46 WG. Fitting - New service kit. Needs Fitting - Innovate XD-16 Kit, Kokeln IC. Stephen's K27 HFS, EVO Intake Assy & his Modded USA Fuel Head. 1983 UK 911 3.2 Carrera Sport Coupe. Black, Black Leather with Red Piping, Black Alloy Gear Knob, K&N Air Filter Element, Turbo Tie rods. Needs Fitting - K&N CO Sensor, Round A/F Dial Gauge, Factory Short Shift Kit. http://www.danasoft.com/sig/Iamnotanumber.jpg |
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Registered
Join Date: Nov 2007
Location: Calgary AB
Posts: 249
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Nathan,
I am running a stock IC and turbo and min 95 octane.
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Q 1991 RRC 1995 993 C2 2002 996TT 1984 930 Turbo (gone and missed) |
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Automotive Monomaniac
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I should add that I dropped down to a stock spring only because California's gas sucks (only 91 octane), and I was getting predetonation.
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