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Location: San Diego, CA
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83 SC timing/idle speed question
OK, as I posted before I failed smog last weekend due to a high idle/bad timing issue. I was trying to fix it this weekend and have the following questions:
(all with car warmed up) 1) the idle speed sitting is ~900-950 - this is good. 2) I go to set timing based on Waytne's book and EPA decal on hood. 2a) disconnect vacuum lines and restart car, idle is now at ~1100-1200 2b) timing is perfect 5 BTDC Do I have to reset the idle to be 950+- 50 WITH the vacuum lines disconnected and reset the timing accordingly? If so what will that do to the idle when they are reconnected? And will it also mess up anything else to reset the idle and timing with vacuum lines disconnected? If not, is there a section of Wayne's book or the Bentley that I can bring the guy to show him the proper procedure? Thanks, Andy
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Andy 83 911SC Targa |
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12-23-2007, 12:57 PM
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Hello Andy,
The procedure is to disconnect and plug the vacuum lines, set the idle speed to 950 rpm, then set the timing to 5 BTDC. When you reconnect the vacuum lines, timing will be pulled back to TDC, the idle speed will change, and you need to reset it at 950 rpm. After you pass emissions, you may want to disconnect and plug the vacuum retard. Its sole purpose is to meet the curb idle test and disconnecting it improves cold starting and lowers oil temperature at hot idle. Paul
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Paul |
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12-23-2007, 03:26 PM
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OK, that makes sense.
But when I take it to the smog place, the guy is going to check the timing. To do that, he will have to disconnect the vacuum hoses, which causes the idle to go from 950 to ~1100. Then he fails me because the idle is too high (spec calls for 950) Am I just in a Catch 22 here? Or is there a problem I'm not seeing? Should the idle speed not increase when the hoses are disconnected from the distributor?
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Andy 83 911SC Targa |
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12-24-2007, 06:42 AM
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Hello Andy,
No, your car is fine, it is the tech that needs an adjustment.
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Paul |
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12-24-2007, 08:00 AM
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I know I'm beating a dead horse here and I really appreciate your help Paul, but the idle increase when the vacuum hoses are disconnected is normal, correct?
I'm just trying to arm myself with knowledge for the tech so i don't fail again.
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Andy 83 911SC Targa |
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12-24-2007, 12:41 PM
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baldman,
My SC's idle changes too when the lines are disconnected. Do not worry!
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Daryl G. 1981 911 SC - sold 06/29/12 |
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12-24-2007, 02:23 PM
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Thank you gentleman. Now the trick is to get the smog guy to quit messing with me!
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Andy 83 911SC Targa |
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12-26-2007, 05:59 AM
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Well, it looks like it's off to the referee.
I talked to the smog guy about the procedure for timing: disconnect vacuum hoses reset idle to 950 set timing reconnect hoses reset idle to 950 According to him because of the new rules California (Commiefornia?) has, he is not allowed (nor am I) to make any adjustments to the car during the test. So we can't reset the idle speed to check the timing.... If I do it at home then I come in with a car idling at less than 950, so it fails there... If I plug the hoses then the emissions system is "broken" and it fails... I'm going to call Black Forest (local shop) and see what they recommend... This state really sucks.
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Andy 83 911SC Targa |
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12-26-2007, 02:47 PM
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