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Banned
Join Date: Apr 2004
Location: Portugal
Posts: 1,513
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decel valve hose
I've just got stranded a few hours ago as my car wouldn't start from cold.
It sputtered and caught on for a few seconds, but it always stalled... Popping the hood and taking a look, I found one end of the hose that connects to the top of the decel valve loose. I tried to "feel" where that end would go, but couldn't find it... Could this be the culprit for the non start ? And can anyone give a hint (a photo would be nice) as to where that end of the hose connects to ? Car is a 74 S |
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07-06-2009, 01:09 PM
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grateful user
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  this should help
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fully disassembled, blasted, customized and restored 75 targa with factory hard top, 993 style turbo ft fenders, steel flares, C2 bumpers and rockers, 82 3.0 sc 9.5/1 engine with PMS flywheel, 964 cams, flowed heads, ssi's short geared 915 w/lsd, polybronze, bilstein,working lambda, modified and highly tuned cis, tensioners, pop valve, backdated exhaust and heater, 2300 lbs. no bolt left untouched. 1970 911E. Nice car but needs a re-do. |
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07-06-2009, 02:22 PM
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Banned
Join Date: Apr 2004
Location: Portugal
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thanks for the pics, but what I think is my decel valve doesn't look like that.
it sits upright behind the big black rubber boot of the CIS, on the left side... round, almost cilindrical with one thin hose on top, and a thicker one below... |
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07-06-2009, 02:29 PM
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grateful user
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sorry, didnt see your sig. 74 has no decel valve, i think your talking about your thermal time swith for your control pressure regulator. one goes to your cpr, or warm up regulator as some call it, and i think you hook the other one up to vacuum on the lower half of your throttle body, same place that you see in my pic where i capt off my decel valve, paul, tony, is that correct?
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fully disassembled, blasted, customized and restored 75 targa with factory hard top, 993 style turbo ft fenders, steel flares, C2 bumpers and rockers, 82 3.0 sc 9.5/1 engine with PMS flywheel, 964 cams, flowed heads, ssi's short geared 915 w/lsd, polybronze, bilstein,working lambda, modified and highly tuned cis, tensioners, pop valve, backdated exhaust and heater, 2300 lbs. no bolt left untouched. 1970 911E. Nice car but needs a re-do. |
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07-06-2009, 02:42 PM
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Banned
Join Date: Apr 2004
Location: Portugal
Posts: 1,513
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Guys, the part I'm talking about is 911-110-220-00-OEM
You can check it at our host shop |
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07-07-2009, 12:33 AM
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Registered
Join Date: Oct 2006
Location: MYR S.C.
Posts: 17,321
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thats the decel valve and if one of th big hoses came off, it could keep it from running. the decel valve bypasses air around the thottle plate when you let off the gas. there is another smaller hose that is connected to it, the smaller one "opens" the decel valve. you can leave the DV or remove it. i removed mine because it was actting up. i later found that it was filled with oil and perhaps this was its problem.
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86 930 94kmiles [_  _] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD88 BMW 325is 200K+ SOLD 03 BMW 330CI 220K:: [_ _] RUNNING: [__] NOT RUNNING:01 suburban 330K:: [_ _] RUNNING: [__] NOT RUNNING:RACE CAR:: sold |
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07-07-2009, 02:59 AM
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Banned
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does anyone have a picture of where the top end hose fo the decel valve goes to, in the throttle body ?
I looked at the diagram in PET but it isn't clear... |
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07-08-2009, 07:34 AM
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its connections are right there at the rear of the throttle body. one connects above th throttle plate and the other side connects below the throttle plate. the 2 hoses are not that long and they are bigger than vacuum lines. you should be able to feel around back there and find it or use a mirror and light.
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86 930 94kmiles [_ _] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD88 BMW 325is 200K+ SOLD 03 BMW 330CI 220K:: [_ _] RUNNING: [__] NOT RUNNING:01 suburban 330K:: [_ _] RUNNING: [__] NOT RUNNING:RACE CAR:: sold |
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07-09-2009, 04:16 AM
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Somatic Negative Optimist
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This is for a '78-'79 but similar to yours.
Your Decel. Valve would be #9. You may have item #4 & 8? It is possible to ignore #4 & 5 and go straight into the rear of the TB like I did. Or you can ignore #4 and use a 'T' to reach the WUR and the TB. Use a mirror and light to find the connecting-nipple for the small vac hose in the back of the TB. Adjust the Decel. Valve to suit your preference for the hang-time when decelerating.  
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1980 Carrerarized SC with SS 3.2, LSD & Extras. SOLD! 1995 seafoam-green 993 C2, LSD, Sport seats.  Abstract Darwin Ipso Facto: "Life is evolutionary random and has no meaning as evidenced by 7 Billion paranoid talking monkeys with super-inflated egos and matching vanity worshipping illusionary Gods and Saviors ". 
Last edited by Gunter; 07-09-2009 at 07:38 AM.. |
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07-09-2009, 07:36 AM
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Banned
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Thanks gunter, I'll take a look into it, although I think my decel valve has just 2 hoses (top, bott) coming out...
BTW, How do you adjust the decel valve ?? |
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07-09-2009, 08:10 AM
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Somatic Negative Optimist
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Take another look.
2 thicker hoses on the bottom. 1 thinner line on top. Adjust by opening the nut on the top line-connection. Remove line, use small wrench to turn the center. Turning cw (down) will increase deceleration. (If I remember right) Turning ccw (Up) will slow down deceleration. Set it to your liking and lock the nut. Replace the small line. Make sure that all un-used connections on the TB are plugged.
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1980 Carrerarized SC with SS 3.2, LSD & Extras. SOLD! 1995 seafoam-green 993 C2, LSD, Sport seats. Abstract Darwin Ipso Facto: "Life is evolutionary random and has no meaning as evidenced by 7 Billion paranoid talking monkeys with super-inflated egos and matching vanity worshipping illusionary Gods and Saviors ".
Last edited by Gunter; 07-13-2009 at 06:11 AM.. Reason: Decrease or increase? |
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07-09-2009, 08:51 AM
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Registered
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3 hoses as gunter said. i used a hand vacuum pump on mine to test it. dont remember the opening pressure, maybe just above 20? i can check it again since it is off the car.
i would not mess with it without a vac pump. do you suspect a problem? i found mine was full of oil after rmoving the throttle body, it was causeing mine to hold the idle hi sometimes, (not why i removed the TB)
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86 930 94kmiles [_ _] RUNNING:[__] NOT RUNNING: ____77 911S widebody: SOLD88 BMW 325is 200K+ SOLD 03 BMW 330CI 220K:: [_ _] RUNNING: [__] NOT RUNNING:01 suburban 330K:: [_ _] RUNNING: [__] NOT RUNNING:RACE CAR:: sold |
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07-10-2009, 03:52 AM
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Banned
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I think it's ok. It's just that the top hose got off and I couldn't find where it goes...
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07-10-2009, 04:21 AM
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Registered
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Location: Miami
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Decel valve connections
Ok, here are some pics...
First with the hoses:  Next the throttle body without the hoses: 
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1979 SC, Slant nose wide-body cab conversion. AEM Infinity EFI, COP, supercharged! |
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07-11-2009, 03:57 PM
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Banned
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Crystal clear !
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07-11-2009, 04:08 PM
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75 Porsche 911
bike
1970 porsche E
ME 262 (SOLD)
Colibri
Gas Mizer
Mileage King
Dog Bus
