Vacuum EGR w/Sniper

[johnsonic]

Hey all!

In the middle of a rebuild, and will eventually get a Sniper setup.

Sorry if this is a naive question - I'm just trying to learn... Wanted to know if anyone is running a Sniper with vacuum EGR?

I'd actually like to have EGR to help with emissions and mainly to keep combustion temps down at idle and cruise, but don't know if it would negatively impact the air fuel ratio or any other problems that would result if the computer isn't controlling the EGR.

If there are no probs running the Sniper with EGR, I'll get the Performer EGR. I really don't want to spend more $$ for the EGR manifold if I'm just going to block it off later.

Anyway - input would be awesome!

Thank you all!

[gpcl16]

I am not running a sniper EFI, I'm running a modified Howell GM TBI system, but I personally found that vacuum controlled EGR function can wreak havoc with the tune. Since the Howell system (inexplicably ) doesn't use the ECU to control the EGR, the ECU doesn't know whether or not the EGR is on and thus, can't compensate by commanding less fuel to the engine. I found that reducing the orifice washer in the EGR helped, and also adding a vacuum delay valve, but eventually just ended up disconnecting it for the time being.

I think that EGR is a good thing to have though if properly tuned. More than anything it will improve your gas milage at light throttle and cruise by introducing inert gas allowing the mixture to use less fuel and reduce pumping losses because it will require more throttle opening to maintain speed. I wouldn't be worried too much about high combustion temps at cruise (though EGR will lower them), and EGR is not active at idle so there won't be any effect there.

I plan on wiring it up with a solenoid to control it (just as the full GM system does) in the near future. I'd also like to do timing control at the same time. I've just been lazy and busy with other projects.

[babywag]

apples vs. oranges

A sniper system utilizes a wide band and therefore is able to learn/deal with afr changes much better than a GM TBI.

You do NOT want EGR active @ idle.
Hookup would be ported vacuum to a CTO to EGR.
A delay valve may be needed as well? To prevent hesitation when opening.
The CTO would prevent EGR until engine is fully warmed up.
It will not be an ideal setup, but I see no harm in experimenting.

[Bill USN-1]

You should not run any emissions on an EFI system, if the system is not controlling it.
EGR, canister purge and air injection, all affect the air or fuel mixure going to the O2 sensor, so it will affect the feed back and the fuel correction.
You can have air injection if it is connected directly to the cat, behind the O2.

For the GM based system, it requires the control solenoid and a VSS since it is temp and speed dependent.

Injection is not a system if it doesn't have timing control.
It's just a carb with O2 feed back.
Better, but not a system.

I have assisted many customers with other companies "systems" to convert to timing control.
I carry the timing control wiring harness to plug into the ECM for the 8 pin module.
Or i can provide everything to convert along with a custom tune.

[babywag]

You should not run any emissions on an EFI system, if the system is not controlling it.
EGR, canister purge and air injection, all affect the air or fuel mixure going to the O2 sensor, so it will affect the feed back and the fuel correction.
You can have air injection if it is connected directly to the cat, behind the O2.

For the GM based system, it requires the control solenoid and a VSS since it is temp and speed dependent.

Injection is not a system if it doesn't have timing control.
It's just a carb with O2 feed back.
Better, but not a system.

I have assisted many customers with other companies "systems" to convert to timing control.
I carry the timing control wiring harness to plug into the ECM for the 8 pin module.
Or i can provide everything to convert along with a custom tune.

True, but it does work on a GM TBI system. In CA we have to pass smog testing which includes a visual inspection and dyno testing.
NOx is MUCH MUCH lower running an EGR like I mentioned above.

Like I said not an ideal setup, but it does function/reduce NOx.
I can post actual smog testing numbers both with and without EGR active.

[Bill USN-1]

You and i were typing at the same time.
I think the lines of discussion are getting blurred and may confuse some reading the information.

There's a difference between emissions operation and proper system operation and control.

[babywag]

You and i were typing at the same time.
I think the lines of discussion are getting blurred and may confuse some reading the information.

There's a difference between emissions operation and proper system operation and control.

Understood. BUT if the goal is to simply reduce emissions it works.
Again NOT ideal setup...

With EGR



Without EGR

[Bill USN-1]

Results are a little confusing when comparing all categories of emission.
So which pollutant would be considered worse?
Your system passed both test, with or without the EGR, as I inform my customers.
Your testing showed a slight increase in CO and HC and a decrease in NO.
So is it better for the enviornment, if that is the only goal?

Another factor to consider is if the activation of the EGR without ECM control causes the O2 to read a different mixture and then while driving, will actually cause the system to adjust the AFR, creating more polution then it would have if you didn't activate the EGR.

So the real question is, are you helping or hurting by doing what you think is helping?

Sort of like buring up an entire forest while trying save the spotted owl habitat.
Did it really help?

https://www.smogtips.com/failed-high-hydrocarbons-HC.cfm

https://www.smogtips.com/failed-high-carbon-monoxide-CO.cfm

https://www.smogtips.com/failed-high-NO-nitric-oxide.cfm

[babywag]

The slight increase could easily be attributed to environmental temp,humidity,etc. differences and rpm differences of testing.

For 3rd time? NOT ideal but will decrease NOx that is what EGR does.

Not going to argue about it..OP asked a question I gave him some info/ .02
Whatever he or others decide to do so be it.

[johnsonic]

Babywag - Thanks for your input! Are you running Sniper w/vacuum EGR or GM TBI? I have all the delay valves / etc so can use them on this motor. Was surprised at how much EGR affected the NO levels?!?! I'm sure I'll be able to pass Oregon DEQ emissions either way (already have with a carb), I just like the idea of cruise temps being lower as I'm often making 200 mile trips through the desert to Idaho in the summer.

Bill USN-1 - I didn't say anything about timing control, but for what it's worth I will have timing control.

Was wondering more about if the Sniper could have the AFR curved based on the manifold vacuum read or if it would recognize that EGR has kicked in. It is a retrofit for older engines and figured someone would have done this in emissions control states.

Goal is to break in the new motor with my current carbed setup because it works and will reduce variables in setting up/breaking in the new engine. Will install the sniper around the 1st oil change. Just want to know if anyone out there is running a Sniper with the stock EGR setup, or has tried it.

Decked my block/heads a little and would like to get the manifold (EGR or No EGR) to the shop to have it shaved if need be before I pick everything up.

Thanks for all your input! This is pretty informative already!

[Bill USN-1]

The slight increase could easily be attributed to environmental temp,humidity,etc. differences and rpm differences of testing.

For 3rd time? NOT ideal but will decrease NOx that is what EGR does.

Not going to argue about it..OP asked a question I gave him some info/ .02
Whatever he or others decide to do so be it.

I'm a little confused, I thought this was just a discussion for information purposes.
Didn't know you took it as an argument.

Johnsonic, timing control discussion was in reference to the other poster, gpcl16.
Howell systems are GM based but they bypass the timing control and run them fuel only like a lot of the cheap aftermarket system being sold now.

[Bill USN-1]

Another discussion on the same topic.

http://fsjnetwork.com/forum/viewtopic.php?f=35&t=15751&sid=525a700350ac754bde98e106526078ef