 jerky deceleration, ow, my neck |
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| r3dplanet |
 Feb 21 2010, 11:07 PM
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#1
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Senior Member  Group: Members Posts: 679 Joined: 3-September 05 From: Portland, Oregon Member No.: 4,741 Region Association: None  |
In my '71 1.7 I hate how it decelerates: when I let off the gas, the RPMs drop to idle in about 0.5 seconds. That might be okay on the track, but its a total pain for daily driving.
I'd check the deceleration valve, but there isn't one. Anything else that might cause such a problem? thanks! |
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Replies(1 - 11)
| jasons |
Feb 21 2010, 11:19 PM
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#2
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Jackstand Extraordinaire Group: Members Posts: 2,002 Joined: 19-August 04 From: Scottsdale, AZ Member No.: 2,573 Region Association: None |
Lightened flywheel? |
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| r3dplanet |
Feb 21 2010, 11:31 PM
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#3
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Senior Member Group: Members Posts: 679 Joined: 3-September 05 From: Portland, Oregon Member No.: 4,741 Region Association: None |
It's possible. The motor has been this way since I've bought it. Is there an easy way to tell?
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| underthetire |
Feb 22 2010, 12:03 AM
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#4
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914 Guru Group: Members Posts: 5,062 Joined: 7-October 08 From: Brentwood Member No.: 9,623 Region Association: Northern California |
The decel valve would help, should have one stock anyways. You might also be lean on the ECU, if your lean the RPM will drop quick.
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| r3dplanet |
Jun 6 2010, 09:56 PM
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#5
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Senior Member Group: Members Posts: 679 Joined: 3-September 05 From: Portland, Oregon Member No.: 4,741 Region Association: None |
Okay. I'm awakening this thread because another member here sent me a shiny deceleration valve. I can see from the diagram in the Haynes manual where the vacuum lines connect .. sort of.
Does anyone have a good photo of their engine bay with a clear view of how the valve is connected and where it bolts into place? I have an early 1.7 liter engine. What confuses me is that the manual shows the 5mm control port vacuum line is somehow spiked in between a very short vacuum line between the thorax of the intake spider and the auxiliary air valve. Thanks! |
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| roadster fan |
Jun 7 2010, 07:39 PM
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#6
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Project Frankenstein !!!!!!!! Group: Members Posts: 1,009 Joined: 24-November 05 From: Aptos, CA Member No.: 5,184 Region Association: Northern California |
I believe there is a rubber "y" fitting to allow you to make the transition form the plenum and aux. air valve. It has a funny bend in it and a connection for the decel valve.
One of the experts will chime in, probably with a part number or pic. Jim |
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| underthetire |
Jun 7 2010, 07:44 PM
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#7
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914 Guru Group: Members Posts: 5,062 Joined: 7-October 08 From: Brentwood Member No.: 9,623 Region Association: Northern California |
QUOTE(spankmeister7 @ Jun 6 2010, 08:56 PM)  thorax of the intake spider Thanks! Thats awesome. My new name for the plenum now. I'm just gonna call it the thorax! I'll take a pic of one and post it if i can find my camera. |
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| roadster fan |
Jun 7 2010, 07:49 PM
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#8
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Project Frankenstein !!!!!!!! Group: Members Posts: 1,009 Joined: 24-November 05 From: Aptos, CA Member No.: 5,184 Region Association: Northern California |
porsche part# 022 133 083 is the part you need to configure the system like the drawing i think. Here is drawing Rubber Fitting It is part #4 in the drawing and list. Hope this helps,
Jim |
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| underthetire |
Jun 7 2010, 07:50 PM
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#9
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914 Guru Group: Members Posts: 5,062 Joined: 7-October 08 From: Brentwood Member No.: 9,623 Region Association: Northern California |
here. goes between the AAR and has a little port for the decel control. Obviously not in us on my car with the megasquirt.
Attached image(s) 
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| narino |
Jun 7 2010, 09:38 PM
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#10
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Member Group: Members Posts: 231 Joined: 14-August 07 From: Los Angeles, CA Member No.: 8,001 Region Association: None 
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Probably a dumb question, but I'm assuming this method is for a FI engine. How would one fix the rapid deceleration on a carburated engine?
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| underthetire |
Jun 7 2010, 10:15 PM
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#11
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914 Guru Group: Members Posts: 5,062 Joined: 7-October 08 From: Brentwood Member No.: 9,623 Region Association: Northern California |
Put fuel injection on it (IMG:style_emoticons/default/piratenanner.gif)
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| r3dplanet |
Jun 7 2010, 11:19 PM
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#12
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Senior Member Group: Members Posts: 679 Joined: 3-September 05 From: Portland, Oregon Member No.: 4,741 Region Association: None |
Yes, the thorax. Sometimes the exact nomenclature escapes me and I sometimes revert to entomological references. I was looking at the plenum, couldn't remember the word "plenum," but decided it looked liked a spider. Hence the thorax.
I'm so incredibly pleased about the "elbow." Thanks so much! I've escalated from lugubrious despair to propitious hope. How pleasing. Now I just hope that this will cure my deceleration issue. I know that the early 914s like mine didn't have a deceleration valve, but perhaps this will solve my issue. Everything else seems to be tip-top. I wonder sometimes if the deceleration valve was added to the mix in later models to deal with issues like this, or whether the differences in ECUs simply made the valve desirable. I just ordered the parts from AA. When I get it installed I'll report back. |
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