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Registered
Join Date: Sep 2016
Location: Franklin, TN
Posts: 188
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Sputters when cold
My 83 SC coupe starts like a champ when cold, however often will sputter (miss?) when I try to give some gas. Once I start driving it does not do this at all ( throttle is responsive, revs well). It only seems to be right when I first start it up?
Any idea what might be causing this problem? |
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05-02-2017, 04:44 AM
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Administrator
Join Date: Feb 2015
Posts: 3,359
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Wonder if this might be a CIS issue...? Warm and cold start problems are common with CIS issues, as well as backfiring and poor performance at startup. Bump, any Pelicans got input for this gentlemen? I posted some info on the CIS below so be sure to take a look at it. Hope you get this figured out.
Porsche 911 CIS Fuel Injection Tuning and Adjustment | 911 (1965-89) - 930 Turbo (1975-89) | Pelican Parts DIY Maintenance Article Last edited by Luccia at Pelican Parts; 05-02-2017 at 07:43 AM.. |
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05-02-2017, 07:41 AM
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Registered
Join Date: Aug 2008
Location: sectors R&N, SE Pa
Posts: 3,117
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Worked on a couple - but no deep experience.
I'll offer some resources and recommend you keep an eye open for Tony (Boyt on here) if he's not on vacation. CIS Troubleshooting for Dummies 911 CIS Primer - Index Troubleshooting chart from above site: 911 CIS Primer - Troubleshooting
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Dan '87 Targa Carrera 3.2 - Fabspeed Cat Bypass, M&K Muffler, SW Chip Venetian Blue |
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05-02-2017, 08:23 AM
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Registered
Join Date: Oct 2006
Location: MYR S.C.
Posts: 17,321
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tony is on vacation 24/7
could be many things. you could have an air leak at a cylinder could be one or several injectors that are not optimal could be something as easy as the mixture needs just a small adjustment. timing ignition, plugs, cap rotor, wires. fuel pressure. if it was my car I would start with fuel pressures. cold and warm I would also look at the plugs to see if any are different than the others, probably right after a cold start. maybe even put in a new set and check them. I have an LM2 so I would check the mixture. if you don't have one I would pull the O2 sensor connector (puts it in open loop) and drive it and see how it runs, then I would check the frequency valve with O2 connected and engine warm. check timing and advance. if none of this pointed to anything I might lean it out then richen it. (I have the LM so I can set it back). I don't suggest this unless you know what you are doing. if still nothing I would check injectors for flow volume and spray. I would also check for air leaks,. check the intake bolts. not knowing the history of the car I might look at the temp sensor. could be bad and in open loop, or closed loop all the time. things like this can take a lot of time. don't throw money at it. test and eliminate. I spent years working on issues like this on my 77 but I may have only worked on it once every 3 or 4 months. about the only thing I would drop money on is a tune up, new wires and perhaps injectors depending on the age/miles.
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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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05-02-2017, 09:17 AM
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Registered
Join Date: Jun 2009
Location: Wilmington, DE
Posts: 1,277
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Tony will set you straight. He is a CIS Yogi
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1983 SC - sold 2002 996 C4S - sold 1968 912 |
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05-02-2017, 02:52 PM
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