ditypup

Would like to hear from everyone what is your take on removing the pair valve and ancillary circuits? I'm pulling the engine on my 93 4x 22RE and now is the opportunity to do it so looking for input and experiences.

scope103

All I can say is: why would you want to bother?

Let see, what sorts of explanations have I heard?
"More horsepower (throttle response, mileage ...)"
Not likely, and I sure am not going to believe it until someone comes up with some dyno runs. The PAIR, or instance, is entirely post-exhaust valves, so how could removing it improve anything?

"Makes doing a future head-gasket replacement easier."
What, you're planning in advance for a whole bunch of head-gasket replacements? If you replace more than one in your ownership of the vehicle, you're clearly doing something wrong. Just wait until you need to do it (if ever), and deal with the vacuum lines then.

And probably my favorite:
"It cleans it up under the hood."
Is your mother in town for a visit? Is she giving you grief for how messy it is in your engine compartment?

If you remove the PAIR (and just about anything else) you'll never be able to register your truck (which means you can't sell it) in any locale with smog control. Plus, every time you remove smog devices, you're just pissing into the air that both of us breathe.

Just one man's opinion.

JasonYota

iTrader: (1)

^^^ Good post.

RustBucket

iTrader: (1)

Judgement laid on thick, but good point about smog inspection.

The PAIR does nothing but squirt air into the exhaust. It's probably just to fool the emission sniffer.

I removed mine. Made no difference. It makes it easier to tinker and makes the engine bay components more visible. It's easier to spot leaks, cracks, etc when there is less crap under the hood.

andykrow

well, just to put another view out there I've got no EGR and no PAIR or air injection (or whatever came on the 86 22re) on my 86 and it runs like a champ. This stuff was removed when I got the truck and I wasn't about to dig through a junk yard to replace this crap. like RustBucket I really like the extra space under the hood.

As for Colorado smog control I'm in Larimer county and passed emissions easily with all levels under 20% of max allowed. There's conflicting stories about what Colorado requires, you apparently don't need all oe emissions equipment here. All they checked for on mine was o2, a cat and the gas cap. Got a "N/A" instead of a "pass" next to the air injection part of the form, which means they weren't looking for it on my rig.

Punchy

The PAIR valve does two things, It keeps exhaust velocity increasing scavenging affect which increases low end torque and for emissions it allows O2 in to clean up the CAT.
The PAIR only opens during decal.


EGR, When working correctly only affects low load cruising.

RustBucket

iTrader: (1)

How does the PAIR help low-end torque if it only opens during deceleration?

snobdds

Here is what I did...

https://www.yotatech.com/forums/f116...-r-vsv-269799/

scope103

Not quite; it is also open with low coolant temp.
http://personal.utulsa.edu/~nathan-b...78pulsedse.pdf

If you're interested in what the PAIR actually does:
http://www.autoshop101.com/forms/h65.pdf

andykrow

Interesting. Makes sense that not having PAIR wouldn't hurt me too bad on emissions since I get the truck nice and hot before running through.

CO emissions is a road test on a dyno with varying speeds throughout the driving range so it tests decel as well.. On that my HC score was 0.894 out of 4.000 allowed grams per mile.

All told it's nice to not dump HC into the air when warming up the truck...

Punchy

The lower end torque is created right after the deceleration, While decelerating the PAIR is open allowing the exhaust gasses to continue through the exhaust pipe creating a scavenging affect which lowers pressure in the cylinders, Minute but it is there.


PAIR is only open for a real short period ((77f) depending on climate) while the engine is cold, This in conjunction with the extra fuel from the cold start inj and ECU running richer heats the CAT faster.


There is no negative performance (When working correctly) from the PAIR what so ever.

ditypup

Interesting guys ............. thanks for the input. Btw I have removed the PAIR valve on my Suzuki VL800K3 and afterwards it now pops quite a bit through the exhaust on deceleration , including hard backfiring sometimes after extreme revs and acceleration, and it is quite annoying to me. Sometimes sounds like a 12 ga shotgun went off (rare). So I might reinstall the PAIR this winter.

It's also possible there is an exhaust leak.

Do de-PAIRed 22RE's exhibit the same symptoms??