1979 3.3 litre emission control problems

RonBo · 03-09-2003, 01:27 AM

My good ol 79 has failed the BC Air Care test,

Nox is too high and the EGR system seems to be at fault.
Problem is I cant find any specifications
on the vaccum line or emission control system.
Half the hoses have been removed or plugged.
If anyone has a schematic of the vaccum system
and/or emission control system or knows of a link
that has it, it would be a big help
79 mustang
3.3 litre straight 6
old holley 1 barrel carb
automatic trans.

84LX89GT · 03-09-2003, 11:55 PM

Although it's not a whole lot of help have you checked out the vacuum diagram that's posted in the engine bay/underside of hood. The diagram shows where all the lines go, although you have to figure out what components the abbreviations stand for.

You could also get a chilton or haynes manual and check out their vacuum section.

A chilton's book i have also explains how the ported vacuum switch works based on engine coolant, which controls EGR operation and at what temp it allows the EGR valve to get vacuum.
According to the haynes manual i have, there is a vacuum line from the "EGR" vacuum port on the carburetor that goes to the middle line on the EGR ported vacuum switch, a vacuum line with a one-way check valve from the spark advance PVS goes to the top line on the EGR PVS. and the bottom line goes to the EGR valve from the EGR PVS.
There is also a spark advance vacuum system with a PVS (cooling PVS). The spark port on the carburetor goes to the top vacuum line on the cooling PVS. The bottom line from the Cooling PVS goes to a manifold vacuum fitting probably tapped into the intake manifold (or in your case "intake log") and the middle line from the PVS goes to a vacuum delay valve, then to a "T". One line from the T goes to the check valve and into the EGR PVS system, and the other vacuum line of the T goes to the vacuum advance on the distributor.
This was a general schematic they gave so hopefully you can figure out something or get a picture (a picture is wortha thousand words, right).
So anyway, i hope this helped somewhat,
good luck

03-12-2003, 04:08 AM

i did too once. but mine is missing all the emission control equipment. what i did is just ran the gas down to a 1/8 of a tank and then added about 4 litres of methyol hydrate ran down to aircare and passed with flying colours (they didn't bother to check under the hood) then got to a gas station right away and filled up the tank. i have seen cars with horrible exhast problems do this and pass. i do not recommend this course of action. but someone in the lower mainland may be able to help you with your problem.

check out the site: www.vancouverstangers.com they are a good local mustang site

03-09-2003, 01:27 AM	#1
RonBo Registered Member Join Date: Mar 2003 Location: BC Canada Posts: 8	1979 3.3 litre emission control problems My good ol 79 has failed the BC Air Care test, Nox is too high and the EGR system seems to be at fault. Problem is I cant find any specifications on the vaccum line or emission control system. Half the hoses have been removed or plugged. If anyone has a schematic of the vaccum system and/or emission control system or knows of a link that has it, it would be a big help 79 mustang 3.3 litre straight 6 old holley 1 barrel carb automatic trans. Last edited by RonBo; 03-09-2003 at 02:28 PM..

03-09-2003, 11:55 PM	#2
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	Although it's not a whole lot of help have you checked out the vacuum diagram that's posted in the engine bay/underside of hood. The diagram shows where all the lines go, although you have to figure out what components the abbreviations stand for. You could also get a chilton or haynes manual and check out their vacuum section. A chilton's book i have also explains how the ported vacuum switch works based on engine coolant, which controls EGR operation and at what temp it allows the EGR valve to get vacuum. According to the haynes manual i have, there is a vacuum line from the "EGR" vacuum port on the carburetor that goes to the middle line on the EGR ported vacuum switch, a vacuum line with a one-way check valve from the spark advance PVS goes to the top line on the EGR PVS. and the bottom line goes to the EGR valve from the EGR PVS. There is also a spark advance vacuum system with a PVS (cooling PVS). The spark port on the carburetor goes to the top vacuum line on the cooling PVS. The bottom line from the Cooling PVS goes to a manifold vacuum fitting probably tapped into the intake manifold (or in your case "intake log") and the middle line from the PVS goes to a vacuum delay valve, then to a "T". One line from the T goes to the check valve and into the EGR PVS system, and the other vacuum line of the T goes to the vacuum advance on the distributor. This was a general schematic they gave so hopefully you can figure out something or get a picture (a picture is wortha thousand words, right). So anyway, i hope this helped somewhat, good luck __________________ 2005 Suzuki Hayabusa GSX1300-R 1980 Ford Thunderbird - 255 V8 ported heads, 5.0L ported stock headers, O.R. H-pipe and Flowmaster 2-chambers, dual roller timing chain hi-po Mack Truck hood emblem 1985 Mustang GT 5.0L T5, F-303, GT40p, headers, off-road h, flowmasters, MSD stuff, etc. Sold 02/06/04 1989 Mustang GT ET: 13.304@102.29 mph (5-24-03) Sold - 1998 Mustang Cobra coupe, 1/4 mile - street tires: 13.843@103.41 (bone stock)

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03-12-2003, 04:08 AM	#3
digital3.3 Guest Posts: n/a	i did too once. but mine is missing all the emission control equipment. what i did is just ran the gas down to a 1/8 of a tank and then added about 4 litres of methyol hydrate ran down to aircare and passed with flying colours (they didn't bother to check under the hood) then got to a gas station right away and filled up the tank. i have seen cars with horrible exhast problems do this and pass. i do not recommend this course of action. but someone in the lower mainland may be able to help you with your problem. check out the site: www.vancouverstangers.com they are a good local mustang site