Early 4.0 tech/advice

tw89yj

tw89yj

Well-Known Member
Joined
Aug 15, 2005
Location
Gastonia, NC
Can you remove all the warmup valve, vacuum hoses, etc, and still run well? I've got a 87 4.0 that I want to clean up and simplify. Is it possible to swap in a HO and retain the existing wiriing?

Thanks, Travis
 
Travis, my 90 MJ witha 4.7 Renix looks naked under the hood after de-emissionizing it.

You can really, really clean it up a lot under there. One of the best things to do is swap a newer (91 and up) valve cover on it. That allows ya a better, cleaner PCV system. Mine has no EGR, EVAP or crankcase vent (aside from the CCV) under the hood. Cleans things up and gives a lot more room. The only vacuum items on mine are for HVAC and fuel pressure regulator function.

Lemme know if I can help ya out.
 
I was hoping you would answer my questions. I'll located a valve cover and start pulling vacuum lines off, thanks.
 
Take all of that tubing crap off the drivers front of the intake. It runs to the airbox, egr, evap and all over under the hood. You can run a push in breather at the front valve cover vent to clean things up.

Get your 91 and newer valve cover from whomever as well as a PCV/MAP vacuum harness from the dealer (call it a 94 XJ 4.0 as far as application goes). Its a much more efficient crankcase vent system.

Before the haters start bashing this action, remember that most all of the emissions devices never work efficiently on the Renix's anyway. By now, most are oil soaked and in poor working order anyway. What you are doing is essentially swapping in more modern, better way of doing it.

Josh is right. You would need a HO harness, pcm and intake (with all sensors) to swap over to true HO status. But there's really no need to. Renix's can support plenty of power and efficiency. Trust me on the power statement...
 
OK so the vaccuum bottle and etc can be removed? I've been toying with cleaning mine up this winter. Anybody have a vacuum diagram of after a cleanup. I figured I'd just take everything out and redo only what I wanted. How do you do away with the EGR?
 
hadfield4wd said:
OK so the vaccuum bottle and etc can be removed? I've been toying with cleaning mine up this winter. Anybody have a vacuum diagram of after a cleanup. I figured I'd just take everything out and redo only what I wanted. How do you do away with the EGR?
Click to expand...

Vacuum diagram will now be: HVAC supply from intake manifold, fuel pressure rgulator from intake, MAP sensor from TB port.

Yep-sure can remove bottle (charcoal canister). As far as EGR disable-unbolt valve, throw away, unbolt solenoid from behind air box, throw away, make a blockoff plate out of the old egr gasket and bolt it on in place of the valve. Unscrew the tube and remove it. Screw pipe plugs in place of tube into the intake and exhaust manifolds.

I'll take a pic tonite for ya Travis. PM me your number-I'll hook ya up.
 
Jody Treadway said:
Yep-sure can. As far as EGR disable-unbolt valve, throw away, unbolt solenoid from behind air box, throw away, make a blockoff plate out of the old egr gasket and bolt it on in place of the valve. Unscrew the tube and remove it. Screw pipe plugs in place of tube into the intake and exhaust manifolds.
I'll take a pic tonite for ya Travis. PM me your number-I'll hook ya up.
Click to expand...

Cool thanks. Then at this case I guess you don't need the vaccum canister either? How do you use the HVAC controls without it? Or do you have that stuff gone as well. I actually have heat and AC in my rig and I'd kind of like to keep it.
 
Any way to identify a '91 and up valve cover? I've got a block with one on it I got for the oil pan a long time ago and don't have a clue as to what year it is....anyone need a block with a baseball size hole in it?:flipoff2:
 
Easy- the rear PCV/CCV grommet will have a 1/4" hole in the middle, the oil cap is flat, about 1.5" diameter, yellow and has a vertical handle for removal.
All other 4.0 oil caps are about 3" and black
 
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