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Engine Sizes, History, and Applications


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Most vehicles that I've come across have a definite vacuum removal diagram. Of course, the PCV, and related components to it that run to the air box, shouldn't be removed for blow-by reasons. In which case, I am thinking of removing all of the vacuum lines that run to the emissions system; EGR, the charcoal canister, and others. I'd like to keep the vacuum lines fort the 4WD actuator, fix it appropriately. Nice to have some 2WD.

In any case, I did some searching but I couldn't find anything on the forum in terms of a diagram for removing the vacuum lines. Rather make it a bit simpler to diagnose any leaks by removing as many as possible then having to use some carb cleaner on all the lines to find a leak.

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The axle disconnect does not exclusively determine 4wd. Jeeps with a CAD system have two points to engage 4wd. The transfercase, and the front axle. Both have to be engaged to be in 4wd.

 

Any Jeep equipped with Full-Time 4wd will not have the axle disconnect, and they began phasing out the CAD in the XJ/MJ in 91, to be completely gone by 93. A good portion of us have permanently locked it in, or replaced the two passenger side shafts with a one piece shaft.

 

The CAD is problematic and unreliable. IMO, you are better off locking it over and forgetting about it, so it isn't a guessing game whether or not you're in 4wd when you pull the lever.

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Though I don't do a lot of highway travel, wouldn't locking it into 4WD be a problem for the TC/front diff/rear diff? I'm not very fluent in the gear ratios for the Comanche (don't even know which rear end I have let alone which trans). Right now it wouldn't be the best idea since I doubt the fluid's ever been changed (getting to that, only owned the Jeep for three days now), but even when I change all the fluids; oil, coolant, trans, TC, front diff, rear diff, clutch/brake, the question still remains (given what the owner's manual says) wouldn't keeping it in 4WD put more wear on the TC/front diff than just keeping it in 2WD and only using the 4WD when applicable? This is my DD, so I need it to be quite reliable, at least through winter.

On a side note, what do you all recommend for gear oil/ATF brands? I'm leaning more towards AMSOil/Valvoline, as any other brand where I live is quite hard to come by, good luck getting Redline/Royal Purple for anything as I doubt any shop/NAPA has ever heard of it (town's a bit of a "WTF is a turbo/sport compact/spool/BOV just getta 350/460/402/318/360" kinda town).

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Locking the CAD DOES NOT lock it in 4wd. It still leaves you with disconnecting the front axle at the T-case.

 

Hopefully these will help:

 

This is what it is now, in 2wd. T-case and CAD both disengaged. Only the rear is powered.

 

This is what happens when you pull the lever to 4wd, and the CAD fails on you. T-case engages, but because the CAD isn't engaged, the front wheels are not powered. Only the rear is powered.

 

This is how it would be with the CAD locked permanently, or with the CAD gone, as they did anyway, with phasing out the CAD. The T-case is still in 2wd mode, so there's no stress on the drivetrain. Only the rear is powered.

 

This is what it's like with the CAD engaged and the T-case in 4wd. This is the only way to get 4wd.

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Digging through some spare car parts I have and came across a generation 1 A'Pexi SAFC (the one with the knobs, not the buttons). Anyone know if the Renix will be able to accept a different incoming signal from the MAP? Curious about this, because the Cavaliers, which I sadly owned before this, were not able to accept an outside tuning device.

As a side note, I go to assume that the injector in the 4.0L throttle body pumps out more CCs/lbs/hour than the 2.5's, however, having a bit of trouble finding any information on the brand of the throttle body as I haven't gotten a chance to look underneath the hood for the past couple of days.

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Nuts. Well, there goes the plan to bolt on the 4.0 TB. Looks like I'll just be working on the port and polish for it along with swapping another fuel injector in sometime down the road; provided I'll be making enough N/A power to actually need to buy a new injector.

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Looking at building an intake for the Comanche to get much better flow than the stock airbox and pipe can offer. Going through www.SiliconeIntakes.com

I'll be using a 3" to 2.5" reducer from the top hat to the 2.5" 17" long intake pipe, couple that with a cone filter with the 'velocity' stack on the end of it. I may or may not use some header wrap/duct heat shielding to keep the intake cool during cruising. However, keeping the intake hot, along with the intake charge itself, will give me some better gas mileage.

 

Here's what I've got for the parts list

3" to 2.5" silicone reducer: 9.99

2.5" worm clamp: 1.49

3" worm clamp: 1.49

2' x 2.5" straight aluminum pipe: 14.99

2.5" inlet cone air filter: 14.99

 

Grand total would come to 44.44 including shipping to the boonies.

I assume that this will improve the gas mileage/horsepower/torque of the engine, but how much is up to speculation. More than likely, it won't be too much. Maybe 1 MPG cruising, 1 HP and 1 ft/lb of torque. But in the end, it just might help overall when cleaning the intake manifold, port matching the throttle body, and a little P&P/gasket matching on the manifold itself.

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If you look at the 2.5 intake manifold youll see that it has a passage for hot coolant to run through it to keep the manifold hot for better fuel atomization. So putting a wrap on an intake tube may not be worth the effort. Ive added the cold air intake to my 2.5, not sure I noticed much power from it, but maybe a little, can't hurt.

 

As far as a bigger throttle body.... Ive contemplated for my future 2.5 build, getting the Clifford 2.5 intake manifold, and trying to adapt a GM 2 barrel throttle body injection, trying to keep as much of the original Comanche contol wiring as possible. I havent done much research on it yet, but at the very least the throttle position sensor appears to use the same voltage range. The fuel delivery pressure and volume would need to be looked at, and idle control would need to be figured out.... maybe re use the original idle solenoid adapted the the 2 bbl linkage? Who knows. My biggest worry would be to see if the original computer could contol two injectors and tune them down enough to keep a good idle, but richen it up fast enough to deal with increased fuel and air demand. Just some stuff to think about. Good luck.

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Adding a secondary injector might screw with the mixture of course, especially if they run in parallel with one another. Along the lines of what I'm trying to do; get a wideband O2 sensor and gauge along with using the A'Pexi SAFC to give some control over the amount of fuel is going into the engine, though I don't know if the piggy-back will work until I give it a shot, but that's for a later date. WBO2 gauges are super expensive. Besides, all the drivetrain fluids need to be changed out before winter really sets in.

Going 2bbl would certainly help the high end if it's not controlled at all, super rich at the low end. Though I'm wondering if the intake mani, even if it's a Clifford, would be able to handle that much more fuel going in it. I'm assuming, since I don't know the flow rate of the OE injector, nor the flow rates of the Chev injectors, that it would need a hell of a lot of air and flow to be able to compensate nicely without much tuning being done.

Anyone happen to know the volumetric efficiency of the engine? I know there's a way to calculate everything, but, well, I had to take algebra many times, so that says something about my math skills.

Also, I'm looking at the vacuum diagram and am thinking about removing the following lines and components:

 

Vacuum Hoses:

EGR Valve to EGR Solenoid Hose

EGR Solenoid to TAC Sensor Hoses (On Throttle Body)

TAC Sensor to Air Cleaner Box Hose

 

Components to Remove:

Charcoal Canister

EGR Valve

EGR Solenoid

 

Components to Block Off:

EGR Valve (if applicable)

TAC Sensor

EGR Solenoid (if applicable)

PCV Air In (Large PCV) - Add Breather

 

The only problem I can conceive that would happen when removing the vacuum lines is a little bit of a hard start during cold weather and some rough idle during the same temperatures given the manifold heater tube would be basically useless. Though I could build an 'air box' heat shield type of thing around the air filter with a port for the tube itself to help out with the initial start and idle before warm up.

I believe that I read in one of the manuals (Hayne's? FSM?) that the Renix ECU is EEPROM. Of course, this means that some of the parameters are adjustable and can be saved via hooking up a computer and essentially programming the ECU that way via a piggy back/stand alone like ECMLink. I highly doubt there are any EMS out there like that, but who knows?

:typing:

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My thoughts with using the chevy injector is that the computer would tune down the injector to the point that it gets the correct mixture... thats the way it does it with the one injector by reading the O2 sensor. If the 02 sensor says its rich, then it turns down the pulse width modulation of the injectors allowing less fuel through till it gets the correct mixture, and fine tunes it from there depending upon speed and load on the engine.It wouldnt be like two regular injectors putting in their normal amounts at idle causing it to be super rich. Makes sense to me at least. Then when you put your foot in it, it richens up quicker, and can handle mixture better at higher RPMs.

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Certainly possible given the fuel maps can change with what the ECU is seeing. Suppose that those throttle bodies are pretty much a dime a dozen, just wiring everything up and making sure that the TPS and IAC can interact with the ECU properly would be the hard part. Worth a shot!

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I was all set to do the front brakes, but apparently I don't have the correct hex socket; standard, not metric. I feels around the lines of a 10 MM hex, but I want to make sure before I go and pick up a set.

Also noticed that when I took the wheels off to check the brakes, that the brake hoses are cracked, down to the fabric even. Obviously, it's more economical to replace the hoses with the OE style rather than the stainless braided, but I might just replace them both with the SS braided. More or less to ensure that they'll last a lot longer and I'll get a bit better feel out of the brakes themselves.

As for the rear drums, are there different sizes, as I noticed on www.RockAuto.com, or just the standard size for the early trucks pre-4.0?

 

On a side note, got a tach installed. SunPro Super Tach 2. Common tach, but it sure is helpful.

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you might want to start breaking these topics up into their own threads so it's all less confusing. :thumbsup:

 

and that charcoal canister is somewhat important. the tank vents excess pressure through it and the charcoal filters out the gasoline. then, when the engine is running, ti sucks the trapped gasoline into the engine. some who have removed it have reported a gasoline smell emitting from the truck.

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I'm not so much worried about the gasoline smell as I can always just cap off the line(s) that lead to the tank. I've removed the EVAP/charcoal canisters from several of my vehicles with no ill effects, save some of the gasoline smell in one. Not a big deal to me though. Just trying to eliminate as many of the lines that aren't truly needed. The less vacuum lines = the less likely a leak. Easier to diagnose and so on.

Heh, sorry about putting all of these in one topic, just trying to keep the forum from getting a bit cluttered up.

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