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Registered
Join Date: Oct 2003
Posts: 455
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1983 928 failed the CO smog test this morning 150,000 miles
Guys,
the ole 28 failed the CO emissions test this morning much to my dismay. Since I'm running 93 octane "enriched" (lol) with up to 10% ethanol here in Tennessee, is there a better choice in gas. In particular, does the 928 test better on low octane or high octane? I'm planning on running some TECHRON through the injectors, but just curious if there is anything else I can do myself. Air cleaner is good. thanks, Paul
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1983 928S 5-speed, 1984 944, 1990 944S2 Cabriolet My other car is a Chris Craft Commander http://www.chriscraftcommander.com |
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10-08-2008, 08:40 AM
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Registered
Join Date: Sep 2005
Location: New Jersey
Posts: 86
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I doubt that gas has anything to do with it
I would first check mixture. That means o2 sensors, mostly. You could also have your cat efficiency checked.
The bottom line is that unless you are doing something special and conscious, a dirty car is a poorly performing car. Obviously things like leaky injectors or truly old plugs could contribute too. Grant |
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10-08-2008, 09:39 AM
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Network Native
Join Date: Jan 2007
Location: SoCal
Posts: 10,349
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Its good to post "all" the info, Euro vs US, and the specific numbers from the test. Grant has it right, most likely a sensor or tuneup related issue.
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10-08-2008, 10:01 AM
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Registered
Join Date: Oct 2003
Posts: 455
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Quote:
The car is an unmodified US spec car in exceptionally good running condition, and the test result was "F" as in "Failed". Unfortunately no data was provided. The car has sat for quite a qhile since the AC does not blow cold and it has been brutally hot in Tennessee. Now in cooler weather, I'm back giving it some exercise. I'm thinking the fuel injection system needs a cleaning. Anyone know how the high octane versus low octane affects the CO readings? PS: The gas we get here is crap, and could well be part of the problem. TECHRON on the way! Paul
__________________
1983 928S 5-speed, 1984 944, 1990 944S2 Cabriolet My other car is a Chris Craft Commander http://www.chriscraftcommander.com |
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10-08-2008, 02:28 PM
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Network Native
Join Date: Jan 2007
Location: SoCal
Posts: 10,349
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I have a US 83 5 spd myself, just finished timing belt, and pulled the intake body and replaced all the vacuum and breather hoses and put on new plug wires and plugs. The injectors were pulled last year and new o rings and hoses put on for them. I must have had two dozen things wrong that got fixed in that marathon, and runs great now.
I wouldn't count on a bottle of Techron doing squat, but use it myself a couple times a year. Our cars should run fine on regular, thats all mine gets, and octane generally will have no effect on smog results. My guess is O2 sensor, cats, maybe a sensor like the temp II, but generally running good sounds more like the O2 and/or cats. O2 bad for long can wreck the cats. BTW the airflow meter has a CO adjustment, has that been set? |
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10-08-2008, 02:59 PM
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