Remove all Emissions Control System?

[applewew]

Hi,

After a few years trying to get my Tercel to run the best possible (see http://tercel4wd.com/forums/viewtopic.php?f=4&t=8069 ), I've decided to just remove anything emissions related that can be removed.

I'd like to do that by keeping the stock carb, since as much as I would like to, I don't have money to buy a weber or similar.

The HIC valve and the "gas filter" (as in the vacuum diagram) are broken and/or plugged with epoxy, and they can't be found anywhere . So, I will need to find another way to "get vacuum" for the timing advance on the distributor.

So far, reading through the FSM, I have the follow list of things that I think can/should and can't/shouldn't be removed:

Can't / shouldn't be removed:

- PCV: Reduces blow-by gas (HC)
- Fuel evaporative emssion control (EVAP): Reduces evaporative HC
- Automatic choke: Improves drivability - cold
- Choke breaker (CB): Improves drivability - cold
- Choke Opener: Improves drivability - hot
- EBCV (or remove it?)
- High Altitude Compensation(HAC) valve
- Deceleration fuel cut system (or remove it?)

From #14 in FAQ
- PCV to intake manifold
- Gas filter to vacuum advance: advances timing 8* at idle and highway cruising for improved fuel economy (how? "gas filter" is broken)
- Vacuum advance port on carb to timing advance unit?
- Charcoal canister to carb egr port? (evaporated fuel from the fuel tank is routed to the charcoal canister and then the intake manifold)

Can / should be removed:

- Air suction valve (or leave it?)
- Exhaust gas recirculation (EGR) valve: Reduces NOx
- EGR Vacuum modulator
- Automatic hot air intake (HAI): Improves drivability - cold
- Hot idle compensation (HIC): Improves air-fuel mixture - hot
- Auxiliary acceleration pump (AAP): Improves drivability - cold
- Heat control valve: Improves drivability - cold
- Cold Mixture heater (CMH): Improves drivability - cold
- EGR Vacuum modulator
- MC Valve
- TVSV

Any help and comments are very appreciated.

[irowiki]

Everything in "can't be removed" should stay, but most of that stuff won't work without a gas filter anyway, including the TVSV which drives most of the stuff under "can't remove".

If you are willing, a gas filter might be able to be mailed to you. It is fundamental for the functioning of your entire system and is pretty much the reason your fuel economy is so low. Without it, removing anything or fixing anything else is pretty much a moot point. If getting some spare parts from us in the US proves to not be possible, saving for a weber is your next best best.

The HIC being bad is another cause for bad running. I do not think you have a MC valve if you have the EBCV.

I speak from experience here. I had an 81 tercel that the PO decided to strip EVERYTHING and manually operate the choke, and seal all the vacuum lines, and that thing ran like crap and got 10-15 MPG.

[applewew]

Getting a gas filter would be great. I can pay via paypal.

Is the HIC obtainable?

[irowiki]

I may have spares of both, but Dan (Gottolovem) definitely does!

[applewew]

I'll PM you.

[Petros]

As Irowiki points out, it is best to have everything working properly rather than jurry rigging by-passes and dealing with poor drivablity.

it will run with out the HAC if properly by passed, some models of Tercels did not have them at all. but if you are at high elevation it is best to keep it.

The AAP can be capped off, it will only affect the cold running, but if it is working (and not leaking) there is no reason to remove it. A ruptured AAP diaphrame is often the a reason for really poor fuel economy, it leaks fule into the intake manifold where it gets sucked into the engine making a really rich mixture, harming both performance and economy.

You can not really remove the TVSV, the fuel and emission systems need it to operated properly. It might be possible to by pass its function, but it means the component controlled by it will be in the warm run condition at all times, even when cold. This may affect cold/start up conditions, but should run normal after start up.

You can not just pull all that stuff out, no matter how frustrating it can be to diagnose and correct, the whole fuel system and drivablity depends on it being there working properly or drivablity and fuel economy may be compromised.

The EGR system can be completely removed without issues, as well as afew other system, but if they are working properly I would just leave them since it reduces emissions. the PVC system for example usually does not affect any other system, and is reliable and needs very little service, no reason to remove it. I have been told that if you have a lot of blow-by the PVC can slightly improve economy by allowing the unburned fuel air mixture to run through the combustion chamber.

[applewew]

Thanks for your input Petros!

I am frustrated. And seeing how simple the weber setup is, I was hoping I could achieve something similar with the stock carb.

So I guess I'm on the hunt for a "gas filter" and a "HIC" valve

[Petros]

The weber has its share of problems too, it needs to be jetted to your engine and altitude conditions, and it has some annoying drivablity issues in both very hot and very cold conditions that the factory carb addresses reasonably well (presuming it is working properly). Though you can find used webers for a resonable price (check E-bay), but you will need to fabricate the adapter and find the correct jets you need.

The factory carb drives very well and is reliable and gives good economy, but it does have a quite a few systems to maintain and repair. Once you know the system it does not take long to test each item and fairly quickly isolate the problem. Most of the operatioal tests do not require special tools and only takes a few min each to perform. There is nothing to be intimidated about, just take it one system at a time. The FSM is good for that.

Good luck.

[dlb]

i like the carb on canadian manual trans tercels because it has no EBCV. the only electronic components are the auto choke and two fuel cutoff solenoids. everything else is vacuum controlled so it's easier to make work if something is amiss.

i find the EBCV to be problematic, and it unfortunately appears in all of the US tercels i have seen. it also sounds like it is in your car as well. that's tough, and makes your job more difficult.

there are many others here who have tried disabling lots of stuff, but i don't recall any of them having much success with smooth running. sorry to bear the bad news.

[Gottolovem]

I may have spares of both, but Dan (Gottolovem) definitely does!

Just so i'm on the same page here the "gas filter" is one of the check valves in the vac system right? (I don't have my FSM here in DC)

[dlb]

the 'gas filter' is the thing with 1, 2, or 3 ports (depending on which emissions system you have) that screws into the first cylinder runner on the intake manifold.

[Gottolovem]

Ok thank's i'll bet I have ten or so

[applewew]

Here is the epoxied valve

Looking at pictures I took in 2012 to the carb, it had two ports.

[irowiki]

A one port gas filter would work too, you'd just use a T fitting