Sniper + desmog EVAP question (1 Viewer)

[candidochris]

Hello - I've been going through my '79 FJ which was de-smogged and has a Sniper on it.

When I dig into the emissions book for a 1981 - I am basically seeing this detail under EVAP.

What I am wondering if there is any downside to connecting the Outer Vent Control Valve directly to switched 12v and one of the Sniper's 3 programmable ground outputs and configuring the Snipper to activate that output when the coolant temp is above 111 degrees.

This would allow eliminating that stock Emissions Computer altogether.

If you're with me this far - what about adding a second Outer Vent Control Valve in place of the BVSV & VCV on the middle cannister line - connecting that to another one of the Sniper's ground outputs and switched 12v and setting that to open when vacuum is above 1.35PSI (2.76 in HG).

Thanks,

Chris

 

[candidochris]

I should fix - on the 2300 Sniper units it would be the fan outputs (still ground output w/ a temp-trigger) - not dedicated ground outputs (so the dual OVCV is not possible).

 

[jhsmith]

Following... And fascinating...

 

[candidochris]

Following... And fascinating...

I made a few mistakes here - 1st the Sniper eliminates the carb bowl evap line all together. Second the sniper used on the 2F is the simpler 2300 with fewer outputs that are preset to their functions.You could definitely, however, use the OVCV setup as a fan relay in the Sniper on the line to the remaining line + the GM Camaro check valve everyone is using to only feed the Evap to the motor when the engine is at temp (emulating the Toyota design) - not sure if that’s a gain at all or not and if the temp matters - I’d imagine it’s better at warm up not to have the evap come on but I doubt it’s worth the effort of repurposing the valve and moving it to the Sniper.

 

[CruisinGA]

Love the concept of using the sniper programmable contacts to manage a simple evap system.

I thought I was going to need to do something similar but turned out that routing the gas tank vents to under the hood and adding the factory check/ pressure relief valve, vented to atmosphere has been working fine with no gas fume smell.

 

[zerotreedelta]

I have the info somewhere (I think it's in one of the YT vids?), but you can actually go a step further and skip any of the vacuum control and use two outputs from the Sniper to drive the purge-valve and recreate the "factory" setup. One ground trigger can be enabled based on coolant temperature, and I used the AC-trigger output based on MAP as the second trigger if I recall.

I needed to add a second solenoid to "join" the two outputs, but then you can use a more modern purge valve, and then the Sniper will basically trigger it to only open when the engine is warmed up and you're off-idle, which is basically what the original setup did.

Amazon product ASIN B07KPK6HQS

 

[WildernessRimFab]

You can also use an Delco 214-2294 evap valve and skip electrical control all together.
@TEQ posted a nice diagram here: https://forum.ih8mud.com/threads/uglina-is-back-thread-78-mustard-fj40.79672/post-14612376

 

[zerotreedelta]

Yeah, similar idea just a different trigger mechanism. I liked using the Sniper outputs as it eliminated the majority of the vacuum lines, reducing chances for future vacuum leaks. Figured I might as well use em when I was doing the install, they're just sitting there.

 

[WildernessRimFab]

Curious to hear how this double sniper output electrical method works out.
Please post up a crude wiring diagram and a few photos if you get it working.
It is definitely more complicated than adding a single additional vac tee and short vac line, but it may work better!

 

[zerotreedelta]

Curious to hear how this double sniper output electrical method works out.
Please post up a crude wiring diagram and a few photos if you get it working.
It is definitely more complicated than adding a single additional vac tee and short vac line, but it may work better!

I'll try to dig up the schematic tonight. It works well, I've been running it for a couple years now.