To PAIR or not to PAIR? (2 Viewers)

[HungryJ0e]

Getting through baselining my new to me '93 FZJ80, and my next big project will be replacing the coolant hoses (to include the PHH and the heater control valve). Before doing that, I'm thinking of doing a PAIR delete. Some background...

When I first bought the truck, there was an exhaust leak... which turned out to be one of the bungs for an O2 sensor which completely rotted out. The O2 sensor was just sitting ontop the exhaust and came out by hand. I had a guy weld a new bung on, and decided to replace the O2 sensor while I was at it... but I couldn't source a '93/'94 sensor so repinned a '95+ sensor for my rig. While my engine runs and idles great, I have heard some folks have trouble with a repinned sensor. I also think replacing the other O2 sensor is probably a wise idea.

So... As far as the PAIR delete, I'd like to clean up the engine bay, remove unnecessary vacuum lines, relocate the new O2 sensors, and open up the possibility of an air compressor well down the road. In prep for this, I bought the '95+ coolant line which runs down where the PAIR sits now. As I mentioned though, the engine currently runs well and idles great.

I started going down the route of PAIR delete, but the nuts on the exhaust manifold are damn tight. I'm concerned about breaking off a stud, which would piss me off to no end. So I sprayed some penetrating oil on the nuts and am letting it sit before reattack, but I wonder if I should just leave well enough alone. Anyone had issues with those studs breaking off, or otherwise want to talk me out of the PAIR delete?

TLDR: Thinking of doing a PAIR delete coupled with the '95+ coolant hardline, but as everything is running nicely right now wondering if I should just move on.

Photo before I attacked the manifold nuts, after I fished the O2 sensor wires into the engine bay and as I was prepping vacuum and airbox line removal...

 

[leonard_nemoy]

Send it

 

[CrabCake]

I've contemplated doing the PAIR delete on mine too, but it runs perfectly fine now, so I don't want to wake any sleeping monsters by upsetting things for really no good reason except for cleaning up the engine compartment.

If you are just looking for space, the PO on mine just re-routed the hose and got rid of the muffler box to make space for the dual battery setup...it does sound like a fart when coming off cruise on deceleration, but not terribly obnoxious.

Here's mine with the hose re-route. Also, I'd leave the old O2's in the pipe to not upset the studs and do new ones in the PAIR holes if I did mine. I did source the correct OEM ones about a year and a half ago when still available and on my shelf...I thought I had a problem, but it was just water in one of the connectors...dried it out, sealed it up, and been fine ever since.

 

[Delta VS]

The only thing I didn’t like about the delete was additional noise at idle.

 

[voodu3]

If you don’t have any issues with the system I’d keep it as is. I was chasing vacuum leaks when I decided to delete the system. It solved my issues. Moving the O2 sensors to the exhaust manifold does keep them out of harm’s way.

 

[RiverCityDave]

I removed mine, and here is my testimony.

My oil cooler (which resides under the exhaust manifold, I'm sure you know) had to be replaced, so no matter what, my manifolds were coming off. The studs came out of the head quickly enough. The nuts connecting to the downpipe were a bit of a chore, but they also relented. I eventually got the nuts off the PAIR studs and removed the manifolds. So, while it was out, I decided to replace ALL the exhaust hardware, figuring it would only be more challenging next time.

New studs at every junction, along with fresh OEM nuts. They are all special nuts and studs with special coatings from Dr T (I'm sure you also know this). Everything came out pretty easy EXCEPT the PAIR studs and the downtube studs. Those required MAP gas, Knipex pliers, and my son's Hercules arms over several days. When they finally broke free, I think the entire neighborhood heard the squeal. (of the stud, not me; I didn't squeal that loud).

That being said, nothing broke despite all the twisting, wrenching, and heating. I'll tell you what: My time would likely have been cut in half if I had bought the Knipex pliers up front. They made ALL the difference. I just realized I never pointed out which Knipex pliers. It was these.

So I agree with @leonard_nemoy above "Send It".

 

[baldilocks]

Relocation of the O2 sensors up out the of crud is justification enough. Once this was finished I made a food warmer tray and bolted it to the engine above the manifolds. This was fun and works well to heat burritos, sandwiches, canned whatever, etc. I know that members mount a York compressor there but is all that air really necessary? Are we planning to open a Mobil trail repair business? There are electric compressors that put out plenty of air for everything except running air tools.

Have you tried using a torch on the pair tubing nuts?

 

[rebelcruiser]

I've had good results with rusted bolts by heating with map gas then spraying with pb blaster. I do this a couple of times. Seems to work better than heat alone.

 

[xetura]

Send it. Take out the EGR as well while you're at it. I'm going to do the same once I get my seat swap finished. I have headers to install and they don't have any provisions for EGR or PAIR, so I have no choice haha. There's a ton of threads on here on what to do. Just make sure you have some kind of heat and a good penetrating oil. I'd heard nothing but good things about SeaFoam Deep Creep, so I picked some up and it is amazing. Also make sure you have new hardware (especially new studs).

 

[CharlieS]

Not sure I'd mess with it unless you have issues. Mine is running great without any of the pair or egr stuff. That much less to fail, and O2 sensors in a much more sensible spot.

 

[HungryJ0e]

Send it. Take out the EGR as well while you're at it. I'm going to do the same once I get my seat swap finished. I have headers to install and they don't have any provisions for EGR or PAIR, so I have no choice haha. There's a ton of threads on here on what to do. Just make sure you have some kind of heat and a good penetrating oil. I'd heard nothing but good things about SeaFoam Deep Creep, so I picked some up and it is amazing. Also make sure you have new hardware (especially new studs).

The JDM EGR is different than the US one. It looks simpler (I don't think there is an electronic actuator) but I haven't studied it enough to really understand what needs to be done.

I've been spraying it with the Deep Creep over the last 24 hours... not sure I want to try and pull the studs though. I think that's asking for a snapped stud.

 

[HungryJ0e]

The only thing I didn’t like about the delete was additional noise at idle.

Can you elaborate? I haven't heard anyone comment on extra noise...

 

[93yotasr5]

I deleted mine. I did not notice any extra noise at all. Remove it and don’t look back.

 

[OffRoadScott]

I deleted mine due to installing a 2nd battery. Was worried about the under-hood inspection for emissions but had no issues.

 

[Cruisin94]

I removed mine, and here is my testimony.

My oil cooler (which resides under the exhaust manifold, I'm sure you know) had to be replaced, so no matter what, my manifolds were coming off. The studs came out of the head easily enough. The nuts connecting to the downpipe were a bit of a chore, but they also relented. I got the nuts off the PAIR studs and removed the manifolds eventually. SO while it was out I decided to replace ALL the exhaust hardware, figuring it would only be more challenging next time.

New studs at every junction, along with fresh OEM nuts. They are all special nuts and studs with special coatings from Dr T (I'm sure you also know this). Everything came out pretty easy EXCEPT the PAIR studs and the downtube studs. Those required MAP gas, Knipex pliers, and my son's Hercules arms over several days. When they finally broke free, I think the entire neighborhood heard the squeal. (of the stud, not me; I didn't squeal that loud).

That being said, nothing broke despite all the twisting, wrenching, and heating. I'll tell you what, my time would likely have been cut in half if I had bought the knipex pliers up front. They made ALL the difference.

So I agree with @leonard_nemoy above "Send It".

What is the dimensions of this stud at the exhaust flange ? I broke mine off, just got it out after welding on a nut to crank it out. Also what is the name of this stud?
This is on my 94 1FZFE

 

[bigredmachine]

delete the pair system and be done with it, i had mine pulled when i swaped out the manifolds for 95-97 years and had other exhaust work done. if you dont want to move the o2 sensors get some 95-97 as they dont have the bung for the pair system and if you want to do a stealth egr delete you can fill in the egr port on the manifold with weld then flat grind it down and get a non egr exhaust manifold gasket to seal it up.

 

[JoeCova]

Deleted mine, YR plates on the exhaust, relocated O2 sensors, plugged the intake, used the 95+ hardline, zip tied the throttle cable, plugged the vacuum line.

If you keep it, at least plug your vacuum line back in.