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Renix emmissions and electrical

N

never monday

NAXJA Forum User
Location
Atlanta, GA
I'm gutting an 87 XJ. I want to run it on a togle switch and push button start.

What needs to be kept in the factory harness for the FI? For the AW4?
I get I'll need power for the computer and fuel pump. But there seems to be a main harness on the left side. Then a second harness from the computer. They intertwine under the dash and in the engine bay. Any help here would be appreciated.

How much of this vacuum emissios crap is necessary on a dedicated trail rig?
 
never monday said:
I'm gutting an 87 XJ. I want to run it on a togle switch and push button start.

What needs to be kept in the factory harness for the FI? For the AW4?
I get I'll need power for the computer and fuel pump. But there seems to be a main harness on the left side. Then a second harness from the computer. They intertwine under the dash and in the engine bay. Any help here would be appreciated.

How much of this vacuum emissios crap is necessary on a dedicated trail rig?
Click to expand...

What, exactly, are you trying to do? You can use a toggle switch to start the thing - just break the lead from the ignition switch underdash and route it to a toggle, instead of to the OEM switch. You'll still need the key lock (unless you manage to disable the column lock) and you'll still need to turn the key to ON (unless you disable the column lock and you install another toggle and a relay to turn power on to everything and bypass the ignition switch underdash.) Use a momentary toggle (turns off when you let go) for the starter switch, and use an ON/OFF for the main switch.

Since the engine controller gets a lot of its signals from the "vacuum crap," and it also helps control things like fuel pressure, you need most of it. You can run without the EGR (the engine is actually cleaner without it. It's not me saying so - I've had emissions reports that show it!) and you may or may not have a disconnect on your front axle that is vacuum-actuated (depends on which transfer case. If you have a "Full Time" four-wheel-drive setting, you have the NP242 and do not have the vacuum disconnect. If you don't have the "Full Time" setting, you have the NP231 and you do have the vacuum shifter on the front axle.) The front axle shifter can be set up to be actuated with a cable, or can be removed for an aftermarket unit that is cable-operated, or you can install a "solid" front axle (without the disconnect) from an NP242-equipped XJ, or a 1991-up (?) XJ with the NP231. It's easy to spot the disconnect. However, since it's a trail rig, avoid 2000 and 2001 donors (and maybe the 1999,) since those axles are "low pinion" units. The earlier ones are "high pinion," and you get better driveshaft angles at lift.
 
never monday said:
Rid the truck of all wiring and emissions except the minimum necessary to make it operate. I have no dash, I'm making a steering column.
I'm non disco on my 30.
Click to expand...

No need to make one - it's a standard GM column, and you can get them at any boneyard (used) or speed shop (new.) Summit and Jeg's will also have them.

There's not a great deal you can get rid of, unless you decide to start from scratch. Ditch the EGR (which is of dubious utility anyhow) but you'll have to block off the valve mounting pad and threaded bung in the bottom of the intake. Should need the same size bung for the header. No, I don't know what size they are - I've been trying to find out myself. When you do, would you please let me know?

No vacuum disco to worry about, so that's fine. If you don't need the heater, you can probably ditch some plumbing there - cap off the heater hose nipple on the thermostat housing, and install a pipe plug in the port on the water pump (it's threaded 3/8" NPT.) This would be a case where I would suggest conversion to an open system - not because it's any better, but because you can make it simpler (since the RENIX "closed" system - like you've got - is fully pressurised an the volume tank is plumbed into the heater lines. Get the later radiator and a non-pressurised recovery tank, and you can eliminate heater plumbing altogether...)

You'll need the vacuum line to the MAP sensor, to the fuel pressure regulator, and probably a few other things I can't think of at the moment.

This would be an interesting project. If you don't hear from me later to-night, would you please remind me backchannel? A PM should serve...
 
lawsoncl said:
It sounds like your main goal is to drop weight and go fast, right? I'm not sure you'd save more than a few pounds trying to trim out fuel injection sensors.
Click to expand...

once again.... I'm trying to make the FI stand alone so it will run without all the factory emissions and extra electrical stuff

imagine if you will taking a Renix 4.0 and puting it in a carburated CJ...that's what I need to do.
 
That is all really complex....... I just rednecked the darn thing and shaved off the locking pin in the ignition....... very simple, very easy. makes it look like a key but the key is optional at that point.
 
Yeah - thought so. I'd gotten your PM, and this thread is just fine where it is.

The problem with making F/I "stand on its own" is that it really needs all those inputs to function effectively. If you want to get rid of more than we've already discussed, you're probably going to need to go to a DIY system - like MegaSquirt by Bowling & Grippo - but I think even the MS has a batch of engine status inputs that it wants.

Going into "weight loss" and such would be AdFab, but not this. I didn't get a chance to check into things last night, so I'll see what I can come up with for you to-day.
 
5-90 said:
Yeah - thought so. I'd gotten your PM, and this thread is just fine where it is.

The problem with making F/I "stand on its own" is that it really needs all those inputs to function effectively. If you want to get rid of more than we've already discussed, you're probably going to need to go to a DIY system - like MegaSquirt by Bowling & Grippo - but I think even the MS has a batch of engine status inputs that it wants.

Going into "weight loss" and such would be AdFab, but not this. I didn't get a chance to check into things last night, so I'll see what I can come up with for you to-day.
Click to expand...
I guess I'm not making clear what I want to accomplish.

A stock XJ has miles of wiring. Turn signals, HVAC, stereo, wipers, FI system. I want to segregate the FI system of it's own from the rest of the harness and truck.

Has no one ever done this?

Please don't read into and guess what I'm after. It seems easy enough. I'd just like to find a person who has successfully done this.
 
never monday said:
I guess I'm not making clear what I want to accomplish.

A stock XJ has miles of wiring. Turn signals, HVAC, stereo, wipers, FI system. I want to segregate the FI system of it's own from the rest of the harness and truck.

Has no one ever done this?

Please don't read into and guess what I'm after. It seems easy enough. I'd just like to find a person who has successfully done this.
Click to expand...

A/C can be removed easily - but you'll want a "delete pully" to do the job right. It mounts in place of the compressor, but it's just an idler pully. You can usually find one at a boneyard.

Turn signals can come in handy on a trail run - I'd think - as can hazzards. Not much weight there anyhow, relatively speaking. Leave the illumination systems be.

Stereo? You can pull the head unit - perhaps put a CB in its place (which would get it out of the way?) That would allow you to remove the speakers as well, but getting all the wiring for them would be a pain (unless you plan to strip the interior anyhow.)

Wipers? I'd keep them - what if it starts raining while you're out on the trail?

Deleting the aircon is probably going to be the biggest "weight savings" for what you're trying to do, and you'll be able to get rid of the compressor, the condenser (in front of the radiator,) the accumulator (also in the engine bay,) the lines - and the evapourator, if you're so inclined. Switch to the later radiator and delete the heater lines, and you can delete the entire HVAC plenum if you like.

It's just the tone of what you were asking in PM and what people were trying to say here seemed like weight savings - you're just trying to simplify vehicle systems, no? I thought that was what I was trying to help you do (and why this thread seemed to be just fine where it is...) You're just going to run into the problem of the "modern" electronic fuel injection setups actually needing most of those inputs to function effectively - unless you want to swap back to a carburettor. So, we're stripping out systems you just don't need (in an effort at simplifying) to get much crap out of the way.

Or am I misunderstanding your intentions?
 
the iac wiring can be deleted.....my renix runs fine without the iac connected.The egr wiring and associated vacuum lines can be deleted as well.

I think in order to make the fi system "stand alone" you would want to cut all the wires that run into and out of the ecm and run all new wires to the various sensors.....sounds to me like a carb would be the simplest way to get rid of all the wires.Gobs of wiring is just the nature of the beast for fi.

that or drop in a diesel motor.....
 
never monday said:
once again.... I'm trying to make the FI stand alone so it will run without all the factory emissions and extra electrical stuff

imagine if you will taking a Renix 4.0 and puting it in a carburated CJ...that's what I need to do.
Click to expand...

Okay.

There really isn't that much in the way of extraneous emissions on a Renix other than the EGR and the cat. There are no electronic evap valves, purge solenoids, secondary O2 sensors, etc like you find on newer vehicles. If you're staying with the Renix FI, then you need to keep all the sensors. You can go through the harness and strip out all the wires for accessories that you remove, but that seems like a lot of work. You can trace all the wires on the yellow diagnostic connectors under the hood back and cut them.

If I were to try to transplant the engine and FI system into another vehicle, I'd probably keep the engine bay harness relatively intact. For the section of the harness inside, I'd either eliminate the C101 connector, or just chop the harness just inside and splice just the wires I need for the PCM. Or maybe just mount the PCM in the engine bay in a watertight container. I've seen a few folks use tupperware and silicon.

Other things you could delete. Get rid of the temp switch on the fan and either wire it always on or have a switch in the cab. Rip out all the vacumn lines for the hvac stuff and eliminate the vacumn ball and the evap/charcol canister. I'd keep the vacumn lines from the valve cover to cut down on blow-by, the line to the map, line to the fuel reg, and the brake booster and cap any the other lines off.

The trans computer is pretty much standalone, other than getting an input from the TPS sensor. You could go with an AWshifting setup and eliminate it altogether though.

How are you with wiring and reading a wiring schematic or tracing wires? I don't mean this as an insult, but there are many folks who go numb when thye look at a wiring schematic and don't know what a voltmeter is. I think some skill and understanding of how the system works is a must. Otherwise I foresee you coming back in a few weeks with a posting titles "I simplified my wiring harness, now it won't start".
 
lawsoncl said:
Okay.

There really isn't that much in the way of extraneous emissions on a Renix other than the EGR and the cat. There are no electronic evap valves, purge solenoids, secondary O2 sensors, etc like you find on newer vehicles. If you're staying with the Renix FI, then you need to keep all the sensors. You can go through the harness and strip out all the wires for accessories that you remove, but that seems like a lot of work. You can trace all the wires on the yellow diagnostic connectors under the hood back and cut them.

If I were to try to transplant the engine and FI system into another vehicle, I'd probably keep the engine bay harness relatively intact. For the section of the harness inside, I'd either eliminate the C101 connector, or just chop the harness just inside and splice just the wires I need for the PCM. Or maybe just mount the PCM in the engine bay in a watertight container. I've seen a few folks use tupperware and silicon.

Other things you could delete. Get rid of the temp switch on the fan and either wire it always on or have a switch in the cab. Rip out all the vacumn lines for the hvac stuff and eliminate the vacumn ball and the evap/charcol canister. I'd keep the vacumn lines from the valve cover to cut down on blow-by, the line to the map, line to the fuel reg, and the brake booster and cap any the other lines off.

The trans computer is pretty much standalone, other than getting an input from the TPS sensor. You could go with an AWshifting setup and eliminate it altogether though.

How are you with wiring and reading a wiring schematic or tracing wires? I don't mean this as an insult, but there are many folks who go numb when thye look at a wiring schematic and don't know what a voltmeter is. I think some skill and understanding of how the system works is a must. Otherwise I foresee you coming back in a few weeks with a posting titles "I simplified my wiring harness, now it won't start".
Click to expand...

Now thats what I'm talking about!! :cheers:

Otherwise I foresee you coming back in a few weeks with a posting titles "I simplified my wiring harness, now it won't start".
Click to expand...
That's what I'm trying to avoid. And avoid rewiring. I'm not opposed to it. It's just time consuming. I think striping out the harness would be easier. I also have a nagging feeling that changing resistance of the harness with butt connectors will cause headaches.
 
I prefer soldering and heat shrink over butt connectors. They aren't overly reliable and take up too much room if you've got a lot of wires to splice.
 
Soldering creates a hard point. On a vehicle that is likley to see alot of flex, that can result in fractures in the wiring. I've seen this happen in the boats I wire for a living.
 
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