Subject	Re: My thermostat was replaced 15k ago.
Posted by	hmb on January 22, 2013 at 6:48 PM
	This message has been viewed 144 times.
In Reply To	My thermostat was replaced 15k ago. posted by MrPulldown(Tahoe) on January 22, 2013 at 06:13 PM
Message	It sounds like you are trying to troubleshoot why your car failed emission testing at idle. For a 1990 300ZX with a stock ECU to pass a stringent idle emission test for CO level, it needs to have a functional AIV system. A stock ECU will run the engine slightly rich at idle, which is not a problem with a functional AIV system that allows the cats to burn off the extra fuel. With a non-functional AIV system, the car will typically fail emission testing with a high CO measurement in the exhaust gas.
Follow Ups	Fan Clutch ? - MrPulldown(Tahoe) 12:50:03 01/22/13 It will always be spinning. (n/m) - Woody75 (Denver) 12:56:43 01/22/13 Re: It will always be spinning. - MrPulldown(Tahoe) 13:14:33 01/22/13 A clutch fan is belt driven and will always spin - white22sky 13:18:24 01/22/13 always spinning - JaffaUK 13:18:59 01/22/13 Thanks. (n/m) - MrPulldown(Tahoe) 14:36:44 01/22/13 I think it expands and will slip less when hot (n/m) - njz 14:57:20 01/22/13 Correct. As engine/bay temp rises, so does fan speed. - Multi_Read (MO) 16:33:33 01/22/13 I had my car on a scope when it failed smog last. - MrPulldown(Tahoe) 15:10:11 01/22/13 your O2 sensors aren't supposed to cycle at idle - aliaZ 15:14:48 01/22/13 I think this is up to debate - MrPulldown(Tahoe) 15:56:26 01/22/13 He knows it does, but running cool will run rich at idle. - TriniTT 16:06:35 01/22/13 I'm trying. Am hoping this new fan clutch does it. - MrPulldown(Tahoe) 16:29:46 01/22/13 Thermostat. (n/m) - TriniTT 17:11:04 01/22/13 ^^^ Thermostat (n/m) - njz 18:13:09 01/22/13 The FSM says to rev to around 2000 RPM to test the O2 - aliaZ 17:28:29 01/22/13 My thermostat was replaced 15k ago. - MrPulldown(Tahoe) 18:13:58 01/22/13 what part of the emissions test did you fail? - aliaZ 18:48:28 01/22/13 Co (n/m) - MrPulldown(Tahoe) 11:14:53 01/23/13 Re: My thermostat was replaced 15k ago. - hmb 18:48:33 01/22/13 My AIV is fully functional. (n/m) - MrPulldown(Tahoe) 11:15:36 01/23/13 I passed w/o AIVs several times - BlackholeZ 13:14:18 01/23/13 Passed with a stock ECU, or an upgraded ECU? (n/m) - hmb 13:46:25 01/23/13 Both - AIV only effects cold start idle (n/m) - Bernie (NoVA) 14:15:02 01/23/13 Stock NA, Ash TT (n/m) - BlackholeZ 02:50:33 01/24/13 They spin and they spin and they spin and they spinnin! (n/m) - boileralum 14:18:00 01/23/13
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