Hello all, Aside from the catalytic converter,the blower, and the belt associated with it, is there other components to the emission system on the 308? Are FI and carborated different in the above equipment list? Are the components visible from the engine compartment? Thanks in advance for sharing your knowledge Cheers!
There are four different general emission configurations on US 308: '73-'77 US 308 carb dual air pump air injection, fuel evap control system, thermal reactor muffler (no cats), R1/R2 point system ignition '78-'79 US 308 carb single air pump air injection, fuel evap control system, 2 cats, R1/R2 point system ignition '80-'82 US 308i and '83 US 308QV single air pump air injection, fuel evap system, egr system, 2 cats '84-'85 US 308QV pulse air injection (no belt driven air pump), fuel evap control system, 1 cat
Steve, that is a very concise list of the emission controls on 308s. I would like to add that the 80-83 cars had air injection not only to nozzles in the cylinder heads, but down pipes to each of the cats. The 84 308 QV also has and oxygen sensor with lambda control (same as later 328). I like the 84 the best, as they did away with all of the air injection pumps, EGR and went to a single cat with a mixture feedback system. Simpler, runs better, easier to pass smog test.
Yes -- didn't want to get too far off in the weeds on the details. The QV air injection nozzle design on the '83 and '84-'85 is also a bit better than the prior 2-valve design, and the "closing airbox with the added evacuation air pump" makes the '78-'79 fuel evap control system the most complicated. Agree with you that the "simplifications" of the '84-'85 are a good thing -- an EGR system is just doomed to bake itself to death .
Adding on to this older thread rather than staring a new one. My '77 GTB has had all of the evap system disconnected, and I'm wanting to install at an evap vapor canister system to minimize fumes in the garage (and help the planet a smidge). Can someone tell me why the RH tank has 3 vent lines going to the air/fuel separator can? I'm wanting to use one of those vents to go to the new vapor canister, but not sure which one to use. Also, it seems to me the rubber vent line between the two tanks is redundant as there is the large alloy air vent tube running between them. What am I missing here?
Not following you here as the line going to the vapor canister should come from the top of the fuel vapor separator, and where the vapor canister connects needs to a location well above the possible level of any liquid fuel -- if you have full tanks, and the RH side of the car is low or in cornering g's, those three nipples on the top of the RH tank will be full of wet fuel. The bigger line between the two tanks is a "balance tube" for moving air in the opposite direction that the liquid fuel is moving between the tanks. The reason there are small lines going from the top of both tanks to the fuel vapor separator is that, regardless of the orientation/tilt/cornering g's of the chassis, the volume of air above the liquid fuel always has a connection to the fuel-vapor separator. You need to include in your thinking (and when looking at figures in your OM and the WSM) that the fuel level in the tanks will not always be perfectly level like in the figures. I assume that you've got the '77 US OM Addendum figure for reference, but what's on the car now feul-evap-wise -- is it the euro set-up with just an open hose connected to the fuel filler tube?
Steve, thanks for the reply. I better understand the small cross tube now. What's on my car is the remnants of the U.S. setup: small cross tube between tanks and the fuel/vapor separator (FVS) connected to one RH tank nipple, then vented to atmosphere via the FVS top hose. No charcoal canister or other valves on the car, though a couple of items with the spare parts that look like the missing valves. What I'm after is the most efficient way to get a working charcoal canister setup, so wondering which tank fittings to use or not, and how necessary is the FVs as I'm unsure about how to determine the internal condition of the FVS. I could go with the factory setup and have the diagram, but it seems unnecessarily complicated, and I'm assuming (perhaps incorrectly) that I'll not be able to find original type components anyway so will have to make do with generic aftermarket parts.
That's OKish functionally, and effectively the euro system (but the end of the vent hose connected to the top of the FVS should be routed to extended down below the chassis frame -- that way no liquid fuel comes out if the car goes upside-down). The FVS isn't complicated -- it just an empty can with baffles and various nipples (see page O16 in the 308GT4 WSM). If it doesn't have any rotting/holes. it's probably OK, can just be rinsed out with some solvent/washing. Having the proper valving/plumbing is the tricky bit (and some charcoal canisters have some built-in valving and some don't). IMO, many cars with an added charcoal canister really don't have a working system -- as you need some way for the engine to dry out the charcoal bed when the engine is running, but without pulling a big vacuum on the (closed) tanks and collapsing them. Getting the stock 3-way valve is probably your biggest challenge, but a lot of these systems have been removed (like yours ) so maybe you can find one. You need the three requirements described in the 308GT4 WSM on page O15 to have a working system: 1. Some way for any pressure (above a very small pressure) in the fuel tanks to be vented to atmosphere, but with that air (and gas fumes) from the tanks passing thru the charcoal bed before being released to atmosphere, 2. Some way for air to be drawn into the tank if there is any vacuum (greater than a small vacuum) in the tanks, and 3. Some way for the engine intake system, when running, to draw a small amount outside air thru the charcoal bed to dry it out. Good Hunting!
