I tried to find the answers by searching, but didn't have any luck

1. How is the system supposed to work?

2. Does the system actually work?

3. What is involved in removing it?

4. Will removing it affect emissions?

Thanks

 

Auto-choke or Sub-Zero Starting Assist? You didn't know there were 2?

Not knowing what model -7 you have makes this question a little harder to answer, but briefly; the carb'd 7's have a mechanical choke butterfly in front of the primary throttle plates in the carb, IIRC, and an electromagnetically controlled choke pull-**** inside the cabin. On cold starts, the driver pulls the choke **** out all the way, and when the engine heats up, the **** will retract on its own. For EFI 7's (84/85 SE's), there is a complicated cold-start mechanism which is initiated when the driver presses the accelerator to the floor ONCE before cranking the engine, which sets a fast-idle cam controlled by a Thermowax Pellet and various heater hoses. As the 13b heats up, the Thermowax Pellet melts, rotating the throttle plates off of the fast idle cam, which opens up the 'secondary throttles' (choke plates) in the Throttle Body.

Both systems have a Sub-Zero Start Assist system which is nothing more than an electric pump like for your windshield washers, but it squirts a 50/50 mix of antifreeze and water into the intake manifold for a very short period of time. This helps to seal the motor for that initial start, and then the system stops squirting this mixture. The correct proportion is printed on the Sub-Zero Start Fluid Tank near the passenger side firewall, below the windshield washer fluid tank.

Yes, these systems actually work in very cold conditions.

Removal is pretty straight forward, but for the Sub-Zero Start Assist, be sure to cap off the tubes going into the intake manifold or you'll have a big vacuum leak.

Removal of these systems shouldn't affect emissions once the engine is warmed up. They actually cause the car to run rich while the engine is getting warm, then switch to standard mix. HTH,

 

I can't find it now but I read in a thread here a short time ago that the sub Zero start system never worked proper and the factory actually had a recall on them because they were found to be worthless .. Just what I was reading

 

could the cold start assist be causing the car to smoke for a minute or two on start up when cold?
I live in Boston, and it's been cold here lately, tonight was actually 2 degree Fahrenheit. After a minute after I turn the car on, the car will smoke more than it does when initially on, the white smoke will get thicker and will climb as high as 12 feet or so before it starts to dissipate. This goes on for about 2-3 minutes until it returns. I just went to check the coolant levels, and I remember I had topped it off pretty high in the summer time, and it hasn't moved from that mark. I also did the champagne test, keeping radiator cap open while engine is warming up, and did not see any bubbles that would indicate a bad coolant seal allowing exhaust to enter the cooling system.

Could the cold start assist cause the car to smoke?

Thanks in advance!

 

Do you run two stroke? That makes my car smoke like hell when its cold, more so when it dropped around freezing temps. just watch the fluid level in your sub zero tank, cause it absolutely would cause smoke when it starts, but probably not as much as youre talking about. My feeling is, if youre not looking coolant, or more oil than normal, it should be fine. Its a rotary.

 

I bet your cold start assist bottle is empty. Most people don't know what it is and never fill it up. Based on this, I bet your smoking issue is not the cold start assist.

 

Thanks for the info. I've got a '85 GSL-SE with the origonal EFI 13b. I didn't know about the auto-choke, and I don't think I'll ever be driving the 7 in sub zero temps, so I think I'll be good. Thanks

 

Mine was never hooked up as far as I can tell, I have the bottle in there and everything just the line seems to go across my engine bay into thin air for no reason. Where is it supposed to terminate so I can block off the vacuum

 

Underneath the intake. I think the FSM calls it a "Dynamic chamber". If you look up the cold start assist in the FSM it should become clear

 

I cant seem to find it. I got all the FSMs for my car from someones forum sig. Maybe someone can get me a picture of where it hooks to the intake cause I cant seem to find a spot where it would hook in.

 

FSM section 4B, page 69

 

I noticed last summer the line from Sub Assist res. to my intake ('84 SE) wasn't hooked up and freaked thinking I've had a huge vac leak all this time. I got the line reconnected without disassembling anything(with much difficulty) and then took the other end off the reservoir...I ran the car, and there was no vacuum pull from that line at all. I thought the reservoir did the job of opening something up on itself and the line sucked the stuff in. My question is: Is this line supposed to have vacuum? If not, how do you activate the intake(not reservoir) side? Also if not, what opens and closes in the intake to open this port?....LongDuck?

 

Good question; actually, there's a temperature controlled spring on the top of the Lower Intake Manifold that's normally covered by the Upper Intake Manifold which looks to me like some kind of mechanical valving system which would be open when it's freaking cold out, and closed all the other times.

Your assumption that it could open up a vacuum source to the Sub-Zero Start reservoir is plausible, as I haven't looked at mine in years to really put any thought into it's operation, as I seem to remember there being a motorized pump (aka windshield washer fluid pump) embedded into the Sub-Zero Start Assist tank, and left it at that. There is definitely some wiring going to that tank, as well, but again - mine has been off the car for years, so I'd have to dig it out to see.

Basically, the top of the Lower Intake Manifold is where this valve is located, and if you're really concerned about vacuum leaks, just plug the one or two brass tubes which protrude. One goes to the Dynamic Chamber (IIRC!), and the other is the Sub-Zero fluid line to the reservoir.

Now you've got me wondering, and I'll have to dig out my Sub-Zero tank tonight when I get home - thanks for that!

 

If I had found that line to have vacuum when I got it reconnected to the intake side, I was going to use the useless sub res. to hold seafoam and then use it whenever I wanted or activate a SpyHunter smoke screen! But alas, no vacuum.
Do please post any info. you might gain if you investigate. Thanks