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cis woes
"77 3.0 Euro: I got the mixture close but the idle surges when cold. Any ideas?
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02-15-2009, 05:01 PM
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Registered
Join Date: Aug 2004
Location: San Antonio, TX
Posts: 1,814
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Surges up and down or idles high?
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Paul 1980 911SC Targa - Sold 1972 914 - Sold |
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02-15-2009, 05:02 PM
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Slumlord
Join Date: May 2001
Location: Canada
Posts: 4,983
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Do you have a set of fuel pressure gages?
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84 Cab - sold! 89 Cab - not quite done 90C4 - winter beater |
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02-15-2009, 05:13 PM
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Almost Banned Once
Join Date: Feb 2009
Location: Adelaide South Australia
Posts: 38,427
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I had a similar issue on my car.
As it turned out it was the Warm Up Regulator. The power wire to the Warm Up Regulator had broken. Might be worth checking. 
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02-15-2009, 05:19 PM
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RETIRED
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When cold, it can be a "Lean Hunt" meaning there is a vacuum leak. Could also be a sign of a bad 02 sensor...or the WUR as mentioned earlier.
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1983/3.6, backdate to long hood 2012 ML350 3.0 Turbo Diesel |
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02-15-2009, 05:38 PM
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Registered
Join Date: Oct 2005
Location: Capistrano Beach, Ca.
Posts: 7,235
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Welcome to the board, sorry it's for a problem but it is most like minor.
Others have pointed in the right direction--typical over-rich surge during cold start--and usually points to a fault with the WUR. Cold system pressure checks are a must to nail this down, using CIS pressure gauges as mentioned. Lots of threads on this board about this so use the search button at the top right and settle in for a bit of informative reading. Type in key words like: "Warm up regulator", "CIS problems", "WUR", etc. Also, take a look at this site for a primer on the CIS: http://members.rennlist.com/jimwms/CIS/CIShome.html Lots of good background.
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L.J. Recovering Porsche-holic Gave up trying to stay clean Stabilized on a Pelican I.V. drip |
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02-15-2009, 05:43 PM
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Designer King
Join Date: Mar 2004
Location: Toronto, ON Canada
Posts: 5,499
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In my experience, a hunting idle usually means a too rich condition. As others have mentioned, checking your cold and warm control pressures w/ a gauge can give you some indication if your WUR is working correctly. I don't know if anyone has published a chart for a '77 3.0 Euro. Maybe a 78/79 3.0 SC spec would work. These years have no O2/lambda system and use a vacuum activated WUR.
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Paul Yellow 77 Sunroof Coupe/cork interior; 3.2L SS '80 engine/10.3:1/No O2; Carrera Tensioners; 11 Blade Fan; Turbo tie rods; Bilstein B6; 28 tube Cooler; SSI, Dansk; MSD/Blaster; 16x7" Fuchs/205/50 Firestone Firehawk Indy 500s; PCA/UCR, MID9 Never leave well enough alone |
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02-16-2009, 06:02 AM
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Registered
Join Date: Nov 2008
Location: Michigan
Posts: 642
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I chased that same problem for about 2 months, on and off. Then it just got so bad, I couldn't get it to idle under 1700rpm. I just got done taring off the CIS, and found a plethera of problems with it. Vaccume line cracks, air box was cracked, all sorts of goofy **** that " shouldn't" have been the underlying problem. So off it stays and I'm going to a carb setup. Good luck, and I hope you don't have my luck. lol
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02-16-2009, 03:01 PM
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I agree with Paulporsche. I have a 77 3.0 Euro as well and had a problem similar to what you describe. Leaned out the mixture a bit and the hunting went away. My snowblower had the same problem.
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"Making things easy is hard work" My current stable: 1991 Carrera 4 Cabriolet, 1992 Mazda Miata, 2004 Lexus RX 330, 1994 F150 4x4 Supercab Also rans: 1977 Carrera 3.0 (traded for C4 Cab.), 1983 944 (project car - sold) |
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02-17-2009, 04:53 AM
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Da cab
Carrera 4 Cabriolet
944
