Making my Renix a little simpler?

[Ecomike]

Diesels can't operate off intake vacuum because they have do not have any vacuum. They are wide open intake all the time and do not have a throttle body. No restriction equals no vacuum. Only time a diesel develops intake vacuum is when the air clearer is really clogged. Same thing happens with the gas motor at WOT which is why we are having the discussion about check valves.

Interestingly enough my Nissan SD22 diesel has a throttle body. It is an odd duck. There are two vacuum lines on opposite sides of the throttle body that are connected to the injection pump pneumatic governor. It reads differential pressure across the throttle body. It is a dual governor, half pneumatic half mechanical Bosch injection pump. !982 vintage out of Nissan 720 PU. They still use this diesel in forklifts.

 

[Ecomike]

In the mean time I think we have left the OP in the dust?

 

[lpennock]

Interestingly enough my Nissan SD22 diesel has a throttle body. It is an odd duck. There are two vacuum lines on opposite sides of the throttle body that are connected to the injection pump pneumatic governor. It reads differential pressure across the throttle body. It is a dual governor, half pneumatic half mechanical Bosch injection pump. !982 vintage out of Nissan 720 PU. They still use this diesel in forklifts.

You're right that is an odd one. Guess I'll have to change that most diesel don't have a throttle body. :dunno:

 

[Ecomike]

The 87 had a an EGR valve, and electric over pneumatic solenoid valve that operates the EGR.

 

[Matthew Currie]

The 87 had a an EGR valve, and electric over pneumatic solenoid valve that operates the EGR.

The solenoid is actually for evaporative purge, but it's tied in with the EGR system. It's been a while since I dealt with it, but I dimly recall that the system is designed so that both don't work at once. But as far as I know, the EGR operates directly off vacuum, and the valve only controls purge.

Not, I suppose, that it's so relevant to this discussion.

I would say there's no particular reason to hold onto the vacuum bottle if you've killed the heater and the axle disco and have no cruise control, but I don't see it as simplifying much either. Considering the electrical mare's nest that exists in an 87, I always thought the vacuum system was refreshingly neat.

With a disco axle shimmed into engagement and no vacuum, this will lose the 4WD indicator light also, but that probably isn't that important either.

 

[1988MJ]

I too appriciate a clean engine bay...:sunshine:

I capped off the EGR at the transducer and removed all the vac lines and the solenoid piece (IIRC the default position is closed) Just have the electrical connector hanging there). Just need to fab a block-off plate for the intake mani. I will do this when I replace my cracked exhaust mani.FWIW, I am experiencing no adverse effects with drivability. And nice to know I am no longer filling my intake manifold with soot...

I removed big plastic tubing running from the charcoal canister to the airbox and capped the fitting on the side of the intake tube. I left the rubber elbow on the canister output and turned it facing down to the ground. So far, no problems with drivability either and no fuel fume smells.

I converted to open cooling system, happily trashing all the rediculous, cumbersome closed system plumbing on the right side of the engine. Hell of alot more piece of mind...Also ran my heater hoses directly to the heater coil, eliminating the valve and capping off the vacuum line to it. A/C still blows ice cold in this Alabama heat and I didn't notice a change in cabin temperature from residual heater core heat.

I unplugged and capped the small vacuum line on the lower intake box that actuates the stupid cold/warm air shutter door and removed the dryer duct hose leading to it from the exhaust manifold. Just need to find a later lower airbox without the stupid hole (this is a throwback from carb days...)

Hope this helps and looking forward to hearing if anyone has anything else to add (er remove :read

 

[uvaldetxj]

i just got married ecomike. my wife doesn't know i'm using naxja, i have to be sneaky like a ninja.

well, i'm still fiddling around with it trying to find out the right configuration. i did disconnect some stuff last night, and while it idled fine...it ran like crap on the road. i reconnected everything, and it ran fine again.

i do appreciate everyones input.
hopefully someone out there has the solution!

 

[Ecomike]

You must keep the MAP sensor (upper middle of the rear firewall) vacuum line to the throttle body hooked up, and have no intake manifold vacuum leaks. It is an engine computer sensor for the fuel injection/air and timing set up run by the computer.

 

[Ecomike]

The solenoid is actually for evaporative purge, but it's tied in with the EGR system. It's been a while since I dealt with it, but I dimly recall that the system is designed so that both don't work at once. But as far as I know, the EGR operates directly off vacuum, and the valve only controls purge.

Not, I suppose, that it's so relevant to this discussion.

I would say there's no particular reason to hold onto the vacuum bottle if you've killed the heater and the axle disco and have no cruise control, but I don't see it as simplifying much either. Considering the electrical mare's nest that exists in an 87, I always thought the vacuum system was refreshingly neat.

With a disco axle shimmed into engagement and no vacuum, this will lose the 4WD indicator light also, but that probably isn't that important either.

The 87-90 are the only years with the EGR, and the EGR solenoid is only for the EGR, that part I am sure of. There is no purge solenoid on the Renix jeeps.

 

[Matthew Currie]

The 87-90 are the only years with the EGR, and the EGR solenoid is only for the EGR, that part I am sure of. There is no purge solenoid on the Renix jeeps.

Look again, and I think you'll find that the solenoid goes to the evaporative system, and not to the EGR. I don't have any books handy here (away from home) and I gave my 87 away years ago, but I'm pretty sure that the two systems are interconnected through that solenoid, and that the EGR is not controlled by the solenoid.

 

[Matthew Currie]

i just got married ecomike. my wife doesn't know i'm using naxja, i have to be sneaky like a ninja.

well, i'm still fiddling around with it trying to find out the right configuration. i did disconnect some stuff last night, and while it idled fine...it ran like crap on the road. i reconnected everything, and it ran fine again.

i do appreciate everyones input.
hopefully someone out there has the solution!

Make sure that whatever you disconnect gets capped.

 

[1988MJ]

The EGR system is in no way connected to the (evap system?) or the fuel vapor recovery system. It is fully self contained on Renix jeeps.

 

[Ecomike]

Look again, and I think you'll find that the solenoid goes to the evaporative system, and not to the EGR. I don't have any books handy here (away from home) and I gave my 87 away years ago, but I'm pretty sure that the two systems are interconnected through that solenoid, and that the EGR is not controlled by the solenoid.

Nope, the 87-89 EGR solenoid has nothing to with the Evap system, only the EGR. I have 2 of them in my driveway. The solenoid is electrically actuated, it applies vacuum to the diaphragm of the EGR only.

Th Evap canister has three ports. One is ambient air inlet, middle is the gas tank vent line, third on the front side goes to the front of the air filter box outlet that goes to the intake manifold. I don't know what if anything is in the line from the Evap can to the gas tank, I am guessing their is pressure check valve in that line somewhere. I don't have a 90 handy to look at. I don't think the 87-90 had an evap purge solenoid, but maybe the 90 had one? I have yet to work on a 90. I am pretty sure the 87-89 does not even have an evap purge valve of any kind. I think it is just a check valve in the line, sort of static. The check valve opens to let the gas tank breath if it gets over pressurized, then vents to the carbon canister in the parking lot, and then purges itself to the intake manifold when the engine is running, with fresh air coming into the charcoal canister to purge the gasoline to the engine intake for burning.

 

[1988MJ]

I just got through tracing the fuel vapor recovery system/canister all the way to the tank and there are no electronics involved. There is a hard line from the firewall to the tank area, it runs alongside the fuel and brake lines on the driverside "frame".

My hoses are in pretty bad shape, wonder if I can relocate the canister to the tank area. Seems to be plenty of room.

 

[Ecomike]

Only problem with moving it is if you plan to get an emissions inspection and they look for it. Does not sound like you are planning on anything but off road, so I am just posting the warning to other readers.

 

[lawsoncl]

You're both right if you consider the 4-cyl setup. Looking at the FSM, the 2.4 setup is different as the solenoid applies vacumn to the EGR and evap canister at the same time. It doesn't show any connections to the evap canister for the 6-cyl.

 

[Ecomike]

You're both right if you consider the 4-cyl setup. Looking at the FSM, the 2.4 setup is different as the solenoid applies vacumn to the EGR and evap canister at the same time. It doesn't show any connections to the evap canister for the 6-cyl.

Interesting.

It was 2.5 wasn't it?

 

[Matthew Currie]

Nope, the 87-89 EGR solenoid has nothing to with the Evap system, only the EGR. I have 2 of them in my driveway. The solenoid is electrically actuated, it applies vacuum to the diaphragm of the EGR only.

Th Evap canister has three ports. One is ambient air inlet, middle is the gas tank vent line, third on the front side goes to the front of the air filter box outlet that goes to the intake manifold. I don't know what if anything is in the line from the Evap can to the gas tank, I am guessing their is pressure check valve in that line somewhere. I don't have a 90 handy to look at. I don't think the 87-90 had an evap purge solenoid, but maybe the 90 had one? I have yet to work on a 90. I am pretty sure the 87-89 does not even have an evap purge valve of any kind. I think it is just a check valve in the line, sort of static. The check valve opens to let the gas tank breath if it gets over pressurized, then vents to the carbon canister in the parking lot, and then purges itself to the intake manifold when the engine is running, with fresh air coming into the charcoal canister to purge the gasoline to the engine intake for burning.

I guess you're right. All the diagrams and literature I see agree with you. I could have sworn my 87 had one of those lines from the solenoid to the canister, and that somewhere I had seen something describing that as canister related, but...well, **** it. It just doesn't seem to be so. I think, however, that it's quite possible my 87's lines were connected wrong. The only other possibility is that they changed it mid-year along with the change in the EGR valve itself. Mine had the earlier version. I'm grasping at straws here, of course.

What I am pretty sure of is that if you yank the whole bloody mess out you'll notice little if any difference.

 

[Ecomike]

Your PO might have followed the 2.5 vacuum line chart and re run the vacuum lines on your 4.0:dunno:

I have seen a lot of late 80s jeeps with creative vacuum line re-routing!
:shocked:

 

[GoSlowGetStuck]

Great thread, was looking for something like this a while back. EGR - I removed everything, put a threaded plug into the exhaust manifold, and JB-welded a close-sized bolt into the intake. Axle disco - ripped all of the lines out, tore out the lines going back to the transfer case as well. Didn't bother putting a plug over the connector on the back of the TC, but probably not a bad idea. Be sure to trace and remove the red (vacuum source) line that eventually goes to the intake manifold, as has been mentioned. The EVAP cansister I have been very tempted to remove, but haven't yet. Main concern is my garage filling with gas fumes, but I think I will cap that off at the fuel tank as well as the air intake tube and put a 3psi (IIRC) pressure-release gas cap on. Another item is the thermostatic air cleaner (TAC), the vacuum motor on the front of the intake box. I sawzall'ed it off of the box and removed the lines. And the big ole vacuum "harness" just on the driver's side of the engine - mostly useless after removing all the other stuff. Leave the vacuum tube going from the valve cover (PCV) to the intake, and run a hose to a breather on the other side. Cap the unused port on the air intake tube.

Usual disclaimer, my XJ is a trail-only rig in a non-emissions state, so if you care about that then don't screw with anything. Basic rules: if it goes from the intake manifold and terminates at a single part (brake booster, MAP, fuel pressure regulator) then leave it. If it goes through an intermediate part (EGR solenoid, EVAP canister, transfer case, etc.) AND you don't care about emissions, then remove it. And of course don't be lazy, remove all the tubing going TO the intake manifold, then it will be obvious that your manifold has a hole that needs to be plugged.