Moses Ludel
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Posts posted by Moses Ludel
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JohnF...I've attached a Jeep Universal shop manual page from the 1965/V-6 CJ introduction era. I would not dispute your installation findings. The Jeep CJ V-6 production came with a lot of adjustments during actual assembly at the factory, shop manuals could not keep up with many of these changes, likely due to adapting the V-6 engine into the CJ chassis. Many of these factory V-6 installations look like an "engine swap", with various and makeshift adapter plates, frame and engine mount adjustments, steering gear and pitman arm changes, and the very strange clearance solution for the exhaust manifolds and head pipe configuration.
The factory illustrations in this PDF may very well reflect the Kaiser/Jeep guidebook you have. The Mitchell parts illustration includes a late Ross gear adaptation that uses the bellcrank, a fore-aft draglink and a one piece tie-rod (circa 1970-71):
When Jeep finally ironed this all out, the CJ was at the end of the Kaiser era and already receiving updated Ross and Saginaw steering gear designs with a one piece tie-rod that eliminated the bellcrank and double tie-rods altogether. Many convert the vintage Jeep/Ross setup to Saginaw recirculating ball-and-nut manual or power steering with a one piece tie-rod that eliminates a variety of issues, including bump-steer. (This approach is outlined in my Jeep CJ Rebuilder's Manual.) Advance Adapters offers the popular Saginaw gear conversion and steering linkage retrofit.
Since you're confident this is the original draglink in the original installation configuration, and since your family Jeep has been driven a considerable distance in this layout, there would be little reason for concern. I would restore the draglink to fit just like it did originally. Follow the OE parts design and the original draglink orientation—install the draglink just like it fit when you removed the piece from the Jeep. Assemble the parts just like Jeep did, and adjust the draglink ends to factory specifications. Make sure the replacement parts fit just like the original pieces.
The aftermarket repair kits are typically "universal". For safety sake, duplicate the factory layout. As for kit spring lengths, consider the amount of collapse at the OEM springs. Be sure the new cup springs fit without creating any bind. Make sure the ball heads of the pitman arm and bellcrank will seat well within the secure areas of the draglink bores. (Be sure that these ball heads cannot jump out of the draglink under any circumstance!) Plugs should fit properly, with cotter pin slots accessible and aligned. Importantly, you must be able to adjust the plug ends to proper specification and spring tension without creating bind or a safety risk. Check for chassis and parts clearance as the installed draglink moves through its full range of travel; also allow for axle and leaf spring movement.
Note that the V-6 Ross cam-and-lever gear housing and pitman arm are not the same as the four-cylinder models. The cross/lever shaft and housing casting are shorter to accommodate the V-6 engine fit. If you dig into the steering gear itself before this is through, I cover the Ross TL gears in my 1946-71 book and also at the magazine. There is even a slideshow on rebuilding a unit:
http://www.4wdmechanix.com/Ross-TL-Steering-Gear-Replacement-Parts.html
http://www.4wdmechanix.com/Rebuilding-the-Ross-TL-Steering-Gear.html
Moses
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whiskies...Turning the axle housing (pinion shaft) upward with tapered shims should do it. I prefer hard steel shims. Watch the spring center bolt heads, make sure they penetrate into the spring perches to keep the axle housing aligned.
When you're done, the splined shaft of the rear driveshaft coupler should penetrate the coupler splines sufficiently and not bottom when the driveshaft collapses fully in service (must work over the full range of rear suspension travel). Establish spline coupler travel with the vehicle at curb height and normally weighted. Allow for proper travel when the springs drop or rise fully.
Strive for the 1.5-2.0 degrees of rear U-joint angle (pinion angled slightly below the driveshaft tube line). Vehicle should be at curb height and loaded. This should eliminate rear driveshaft vibration with a CV driveline.
Keep us posted, glad the project is unfolding without fanfare. What did you do about shift linkage? Both inputs were 23-spline. Were the spline cuts the same, too? Easy fit?
Moses
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Aaron...I do want to see your photos. Please take a set of photos that will illustrate each of your concerns and problems. Include droop and static curb height to narrow down the issue. Clear photos will provide info I need to comment on these concerns. Sounds like you have a safety and handling risk. Send as many photos as you want.
If you're having any difficulty attaching photos, simply click on "More Reply Options", you'll see the provision for attaching photos. I'm looking forward to reviewing your photos, let's get this lift kit and other modifications sorted out.
Quick question: What size tires, wheels and wheel backspacing are you running on the Cherokee?
Thanks!
Moses
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Whiskies...First, for rear driveshaft length, you need to see if the shaft is long enough for the coupler splines to be safely engaged when the rear axle is at full drop. (Allow for additional drop when the axle is articulated.) A quick check without a chassis hoist would be with jack stands supporting the rear of the chassis. Let the axle sag or hang naturally; disconnect the driveline if necessary. The goal is to make sure that the driveshaft, if attached at full axle drop, is not hyperextending. Spline engagement must be enough to not stress the splines or have the shaft come apart!
As for angles at the rear shaft joints, the CV angle is immaterial unless extreme, since one joint of the CV cancels the other joint at the CV coupler. For the rear axle end, your concern is the pinion shaft angle. Rolling the axle (pinion shaft) upward is to reduce the driveline slope and rear U-joint angle. You must not raise the pinion shaft to the point that the driveshaft to pinion shaft angle becomes zero. If you do so, the bearings in the U-joint crosses will not rotate adequately, and the joint will fail quickly.
So, the goal is to get a slight angle between the driveshaft (tube section centerline) and the pinion shaft (a line extending directly from the pinion shaft). On a lifted vehicle with a CV driveline like yours, the angle between the shaft tube and pinion shaft centerline works well around 1.5 to 2.0 degrees. These measurements are with the vehicle's full weight at curb height, either all four wheels on the ground or the vehicle setting on four uniform height jack stands.
Before stressing over a slightly greater rear joint angle, consider the front axle. Caster, as you suggest, dictates the front U-joint angle. In some cases, the front axle's front joint angle is over 2-degrees to allow for proper caster angle. (Caster often gets ignored on lifted vehicles to reduce the U-joint angle; I always use the factory recommended degrees of positive caster.)
Note: Due to front driveshaft length and the front output yoke location on the transfer case, the front driveshaft's slope angle is typically less severe. A Jeep CJ or Wrangler has a shorter wheelbase than an XJ Cherokee. The CJ or Wrangler rear driveshaft is shorter. In your case, the rear driveline is as long or perhaps even longer than the front shaft due to the longer wheelbase.
This factory procedure (below) for the 1994 XJ and YJ will help demystify your driveline measurements. As noted, the axle/pinion shaft rotation is with steel tapered shims that have slots to clear the spring center bolt. (Do you have tapered shims with the lift kit installed?) At the correct U-joint angle setting, make sure the spring center bolt heads reach through the tapered shims (one tapered shim at each side) and seat properly in the spring perches of the axle:
XJ Cherokee U-joint Angles.pdf
Note that if you do need to rotate the rear axle/pinion shaft upward, you will also be moving the rear U-joint yoke closer to the transfer case. This may work to your advantage if the rear driveshaft is too short now.
As a footnote, you don't want a driveshaft to be too long, either. If the splined coupler is collapsed fully at vehicle curb height, when the axle housing rises, the collapsed driveshaft has no room to shorten. Transfer cases have been known to break apart when the collapsed driveshaft drives forward.
Moses
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Good news, 2point5liter! Sounds like defective relay plug sockets and/or the ECU. Waiting for your test drive update and a successful ending...
As for voltage drops and lamp load testing, you should be able to perform this test without removing the harness. You'd leave the harness attached at the power source. Disconnect the harness connector at the powered device and "jumper" the lamp between the connector and the device. (A ground check would be similar.) Check for a voltage drop or dim lamp when powered up.
If your current work solves the problem, lamp load testing can be a tool for down the road!
Moses
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Errol...The J-trucks have a longer wheelbase, which decreases the U-joint operating angles at the rear driveline. This enables the rear axle to have a centered differential despite the offset output from the Quadra-Trac transfer case. You're right, the drop and side offset (think plane and side views) is still within tolerance as long as the U-joint angles are not excessive (which reduces torque capacity) and the angles cancel each other as far as phase goes.
Again, the longer wheelbase makes this possible. On the CJ-7 Jeep at a 94" wheelbase, the rear differential had to line up with the offset output of the Quadra-Trac to help reduce angles at the U-joints. Simple. Compound though it seems, you're correct in noting that it's simply about cancelling the angles of the joints. The flanges are parallel (plane view), and combined side shift and drop is immaterial to the U-joints as long as their rotational arcs are identical and their angles cancel each other. If so, they are in phase.
Moses
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Dave...Would be optimal of that front driveline works or is at least running long. It can be shortened and re-balanced, that's much less expensive if the yokes will work at each end.
If the shaft fits as is, vibration would not be likely if the angle of the rear single Cardan joint is within reason. The lift is mild, and I like your idea of measuring the rear U-joint angle with an angle gauge. It may turn out close or acceptable. The CV joint is a big improvement.
This clocking issue is true, there are differences around the YJ versus XJ and BA10 versus AX15 transmissions. Another issue is the front yoke on the NP231J from an earlier YJ Wrangler. Compare the front driveshaft flange yoke on your NP242 to the NP231 front yoke. The NP242 is definitely for a double-Cardan front CV driveline. The '89 YJ could be a single Cardan (non-CV) joint with a single Cardan joint. Compare the front output flanges.
You can measure the clocking by the bolt hole locations in the six-bolt flange. The difference is around 13 degrees, readily measureable before you fiddle with the swap. Also, YJ shift linkage may be necessary to get the 231 transfer case to work in the XJ Cherokee. Compare the shift linkage designs and what you can do here.
Lastly, the early transfer case may also have a different cut on the input splines. Note the spline count: the NP242 is 23-spline, the NP231 from an '89 model could be 21 spline or 23 spline. If spline count matches, look closely at the cut on the splines to be sure the spline fit matches between the AX4 transmission output shaft and the earlier NP231 transfer case input. The 1994 models were a transition in spline cut design.
Please share your findings. This can be a comprehensive and valuable look at transfer case differences and what works here, Dave.
Moses
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Dave...So, will you be constructing a CV-driveline for the rear? The 231J with an SYE will eliminate the slip yoke style driveshaft at the rear. You currently have a slip yoke at the rear output of the NP242, right?
The common approach is to construct or buy a prebuilt rear CV driveline. The new rear driveshaft will have a double-Cardan (CV) front joint and a common cross-type single Cardan joint for the stock rear axle U-joint flange.
A CV-driveline's front joints (two U-joints with a coupler) have self-cancelling angles. The pinion/axle end joint usually requires tilting the rear axle pinion shaft upward. I like a 1.5-2 degree angle for the rear axle U-joint with the vehicle weighted on the ground at curb height or on axle stands.
If you rotate the rear axle pinion shaft upward, use steel wedge shims at the springs. These commonly come with lift kits or can be purchased from a supplier like Specialty Products. Make sure that the leaf spring center bolts penetrate through the steel wedges and into the axle's spring perches.
Moses
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Hi, Errol, thanks for your astute observation about my time management skills. Fortunately, my children are all grown, most of the grandkids, too, and the spread-thin approach is tolerated by wife and others. Guess they figure if I want to exploit myself on this level, that's my business. I've become a master at delayed gratification. The recent Honda XR650R motorcycle project serves as a metaphor and excuse for getting away from the computer...
If you're doing a THM400, I would simply eliminate the existing transfer case and build your THM400 into a 2WD version with a passenger car or 2WD truck output shaft and tail housing. The scarce commodity here is the AMC V-8 interface at the front of the transmission case. You're creative and can work around this issue. There's no point in having parasitic loss with a side-drive (chain) transfer case that serves no purpose in a 2WD vehicle.
There is one other issue, however. In order to use a straight through output from the THM400 transmission, your J-truck rear axle must have the centered differential. The Jeep CJ models with Warner Quadra-Trac have an offset rear differential. Which type rear axle do you have here?
Moses
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Whiskies...To sift out differences in transfer cases, splines and transfer case input hub lengths, I have furnished the two links (below) to Novak's description. This is the most thorough and detailed account of the NP/NV231J versus NP/NV242. You likely have a bolt-up if the input hub lengths match for your AW-4 output shaft. (This determines engagement of splines.) Spline count should be 23 on both units. Seals must align at the same locations. Novak talks about linkage to an extent.
Measure the input hub lengths and compare the overall lengths of each transfer case. Length and output yoke positioning (fore and aft) will determine driveline interchangeability. I can furnish Mopar part numbers on drivelines to clarify if necessary. Begin by scouring these two pages at the Novak site:
http://www.novak-adapt.com/knowledge/np242.htm
http://www.novak-adapt.com/knowledge/np_nvg_input_gears.htm
Glad to take it from here as necessary...
Moses
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Interesting comments about the 4.8L GM V-8, rockosocko. This would make a good package for an XJ Cherokee or Jeep Wrangler swap. I like your point about the cost difference, the 4.8L being an ignored gem.
Though Dodge/Chrysler is late to the game at encouraging V-8 swaps for Wranglers (JK) and other uses, Mopar has arrived! The 5.7L is readily available now, new or used, and it has potential. Light enough for a Jeep swap, with a quick wiring harness interface and the usual exhaust, cooling system and motor mount solutions, this can be a wise choice—and "all Chrysler". When the Grand Cherokee got the LA pushrod 5.2L and 5.9L MPI engines, Mopar Performance should have taken the charge with an engine package swap into the Jeep YJ and TJ Wranglers. Oh, well, better late than never, GM got the edge here!
Moses
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Errol...The ITB multi-TBI units is a unique idea. I watched your video thoroughly, and you're doing a well thought out induction and fuel delivery system...I like the attention to detail features like the plate transitions and the progressive throttle linkage!
Of course, this could be dialed with bench flow testing and finish porting, but it's apparent that you're onto a very potent induction system! The custom manifold runners look unrestricted, this is a major fuel/air flow gain.
Sync'ing ITBs is crucial, much like running multiple carburetors only in this case it's throttle position switches (TPS) and throttle valves instead of just throttle valves...
I am very curious how this works for a 4.0L inline six. MPI alone meant a 50 horsepower jump over stock 2-barrel carburetion for the 4.2L Jeep/Mopar EFI conversion, and that is a single throttle body...Much potential here, keep us posted, Errol!
Please start a topic on the 4.0L engine build at either the Jeep Wrangler or XJ/ZJ/WJ forum! Note the gains from a 4.2L crankshaft conversion to boost displacement to 4.6L. Lots of 4.6L coverage at the forums and the magazine site.
Moses
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Hi, rockosocko (Errol)! You've got a vintage J-truck/FSJ with the Warner Quadra-Trac 4WD chain drive transfer case. Look in the glove box for the vacuum switch. Follow the hose routing from there to the transfer case.
Here is the vacuum diagram for a typical '73-'79 Warner Quadra-Trac in a Jeep 4x4. This workshop manual photo should suffice for your current repair:
Note that this is the "emergency" control circuit. Quadra-Trac in stock form is full-time 4x4. There are aftermarket conversion kits like the Mile Marker that have turned these transfer cases into "part-time" 4x4 for use with free-wheeling front wheel hub lockouts.
Do you have free-wheeling front wheel hubs? If so, you likely have a part-time 4x4 "kit" installed here. If not, the system is stock full-time 4x4, and the vacuum circuit is an emergency override.
Trust this helps, Errol...
Moses
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That's a new one, ehlinn. Here is the Mopar official parts section for the 1999 XJ Cherokee switches, pay close attention to RHD versus LHD, 2-door versus 4-door and such:
Read the legend at the bottom to distinguish your model type. Switches are different for various world markets.
You can zoom into the pages for details...These are official OEM part numbers.
Trust this helps...
Moses
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2point5liter...I'm an advocate of lamp load testing, especially ground circuits. Continuity tests can be deceiving. A friend recently wrote me with an issue related to his Dodge Ram Cummins truck with 370K miles on the clock. I'll share my comments because your hunt for "continuity" may not be enough on these wiring circuits, especially ground related. Here are my suggestions and comments about ECU troubles:
"…A great test for wiring circuits is the “lamp load test”. This is a simple test involving a spare headlamp, wire leads, an inline fuse and clip or terminal ends. The test indicates not just continuity but also the voltage drop in a wiring circuit. I learned this trick from Eric B., the Carson City Dodge dealership specialist on Cummins engines. We had an issue at 800 miles with our new ’05 Ram 3500, the engine dropped cylinders and threw an ECU code for a #1 cylinder misfire. Eric B., dutifully following the orders of Chrysler engineering and his service manager, swapped and moved injectors around, did all of the “#1 cylinder misfire” troubleshooting and repair measures—to no avail. Other cylinders began throwing “misfire” codes, and Eric suspected the ECU itself. Chrysler said, “Impossible! If defective, the engine management computer [ECU] would self-interrogate and throw a defect code!” There were 25 new Dodge Ram trucks in the region (West Coast to Denver) with the same issue, and Eric persisted. Finally, bending to Eric’s stature and track record, Chrysler approved an ECU replacement on our truck, the first such repair authorized in the zone. As suspected, the problem ended with a Cummins “Recon” ECU in place. At 130K miles, there have been no subsequent issues, and last year, Chrysler sent a VIN driven notice to owners of ‘05/’06 Cummins models, extending ECU replacement to “lifetime” warranty coverage...In the troubleshooting process, Eric analyzed the injector ground circuit with his lamp load test, including injector firing. Injectors fire from an ECU ground signal. (The injector is “hot” at all times and waiting for the ground signal to open the pintle.) Eric shared that the lamp load test was the fastest, most accurate way to find an open or high resistance point in a wiring circuit. Makes perfect sense, this is D.C., and grounds are as critical as the hot leads. Eric ran lamp load tests on both positive and negative circuits to quickly isolate any high resistance points (caused by a short, open or loose connection). He found none…If you find yourself wanting or needing to make this electrical repair, the dimming of the test lamp indicates a short in the circuit...Keep in mind that grounds on a D.C. system are important, they carry as much load as the hot leads."
Does this note to my Cummins Dodge friend resonate, 2point5liter? A short or open could even be related to that power steering switch short to ground that you experienced some time back...Continuity is only part of the story. A voltage drop could be the rest.
Moses
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Hi, Papaobewon...For that extended seal answer and a detailed explanation of any modifications needed, the best information source would be our friends at Advance Adapters. They work with both OE and their own Atlas transfer cases. Since the NP/NV231 is very popular in swaps and for upgrades, any seal issues, improvements and modifications would be addressed by Advance Adapters.
Give them a ring at 1-800-350-2223. Ask for the tech line, and share that I suggested you call. They will be very thorough in responding to the seal question, and if there is a needed extension seal, Advance Adapters would know exactly what modifications, if any, are needed. They can also provide any parts.
Should you want to add the SYE to your original transfer case, Advance Adapters would be my choice.
Moses
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For openers, the manual and automatic transmission versions of the 231J are different in 2000 model year. Each complete transfer case unit has a unique part number.
I know you're academic and can sort through the details of parts distinctions. The sensible approach is to compare the individual parts you have described, noting the Mopar part numbers for each of these transfer cases and their subassemblies. Many parts interchange straight across. Others do not have the same part number, which indicates a difference in design and application.
For your benefit, I have sifted through the Mopar parts catalog covering model year 2000 Jeep TJ Wrangler. Below are the factory parts illustrations and part numbers for the 231 transfer cases and also the 32RH transmission case and extension housing. Here are the pages from Mopar's references, you can zoom into the images for details and fit:
2000 TJ Wrangler Transfer Case Parts.pdf
2000 TJ Wrangler Extension & Cases.pdf
When you seek replacement parts, always begin with identifying the OEM part and its number. Then you can cross-reference part numbers on items like seals. Some parts are OEM only while others have an aftermarket counterpart.
Mopar uses letter codes to identify manual versus automatic transmissions, 4.0L engines versus 2.5L engines, and the chassis and body type for a given model. Note that these parts listings focus on model year 2000, so this will apply to both the Sahara and Sport models. This is the resource I rely upon, first generation and from the OE level.
Moses
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The aftermarket rebuild industry sounds like it's let you down...Mopar has its own Reman system, and perhaps the product would be better than Borg-Warner or Cardone. Borg-Warner was a quality supplier in the day.
The OEM Mopar part number is 53005023. The Mopar Reman (if still available) is JR005023. My Mopar Reman catalog is 2010, and this is the listing for 1986-90 2.5L TBI with manual transmission. These units, as you know, are Fenix types. Check price and availability on this Mopar unit. Also check the part number on your existing ECU.
Moses
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Hertfordnc...Stay in 5th longer, there's no gain to "lugging" the engine...When you can stay above 1600 rpm in 6th, use it...
Moses
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Your motivation and thoroughness is highly commendable, 2point5liter! What an undertaking, you obviously like electrical work. Some would consider this a deal breaker, you're taking it all in stride.
So, the wiring restoration and then the ECU itself? There's an outfit at Idaho (Module Masters) that does module rebuilding and restoration, perhaps they can tackle a fuel-and-spark management computer. There may be other sources for rebuilt ECUs. I'd like to know what you do with the ECU if that turns out to be the trouble spot.
Keep the grounds in mind, this is D.C.! On project vehicles, I upgrade all engine-to-chassis-to-body grounds with 1/0 cable and industrial terminal connections. Grounds: the other half of a D.C. circuit. Good connections, no corrosion "wicking" and no paint barriers!
Moses
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You're welcome, hertfordnc! Once you start driving this way, it becomes habit. "In the day", I tested a lot of trucks for magazines and newspapers, we were always about performance, mileage came under discussion in passing. Today, mileage is a topic of interest for all but a few!
Bigger exhaust and cold intake do offer gains, although fuel mileage improvements might be incremental when considering the way we're both driving these trucks. There's a caveat here: Why would a vehicle manufacturer, bent on meeting CAFE standards for fleet and seeking fuel efficiency bragging rights, consciously avoid mileage gain strategies? Packaging a vehicle does face constraints and tradeoffs, and maybe bigger or space consuming improvements like you mention simply will not fit, or they create assembly challenges.
Exhaust being "bigger", unless scavenging gains are clear, has little impact beyond irritating your neighbors when you come home late at night. Loud exhaust tones have you idling out of the neighborhood when your trip begins before dawn.
As proof in my case, I got the best mileage to date with a stone stock truck. The Hypertech Energy Max programmer was to offset the downside of a chassis lift (the increased frontal drag) and nearly 1200 pounds of really neat accessories and auxiliary fuel now on board that is equivalent to pulling a tent trailer all the time.
The truck runs fantastically, but the power is now further up the rpm scale with peak torque around 2100 rpm. Just the increase from a stock 1600-1900 rpm sweet spot to accomplishing the same road speed at a higher rpm (thank 4.56 gears for this) is enough to burn extra fuel. In fairness, this was not anywhere near an apples for apples test, the truck has too many changes to draw comparisons from stock.
So, when it comes to fuel efficiency versus "performance", Chrysler and Cummins did a good job on these trucks. Driven like a "truck" and not a county fair puller, you can get good mileage. I had the 3.73 gears with the stock tires and did very well for overall fuel efficiency, hauling ability and performance.
Keep driving on your best behavior and see what this package can do for fuel mileage. You may be at peak or near peak right now...At least you'll have a true benchmark with this consistent driving style. If you can get 22-23 mpg at reasonable road speeds, that's about it, frankly.
My best of 25 mpg was at 55-65 mph, empty, stock curb weigh, no lift kit or auxiliary fuel tank, and holding engine speed precisely between 1600-1900 rpm. Interestingly, that trip included mountain passes, so the mileage was apparently influenced more by engine rpm than load.
Moses
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2point5liter...Is your MIL lamp (Engine Check light) glowing? Any codes thrown here? Other than an ECU failure, OBD can offer some insight, especially an O2 or other sensor issues. With the flooding you describe, this sounds bigger than an O2 problem, which at worst would throw the system into limp home mode. That mode or WOT mode would run rich but not deliver the excess of fuel you're describing here.
A repetitive code could be insightful, and that's the reason for storing codes. The only code that never seems to appear is a failing ECU. The microprocessor has trouble troubleshooting itself. Stored codes can be picked up with anything from a simple code reader to a DRB or equivalent scan tool. This system is not OBD-II, however, so there's a limit to its diagnostic and troubleshooting capabilities.
Moses
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You're on the right track, 2point5liter. The fuel pressure regulator diaphragm is spring counterbalance pressure, and you need the correct spring and regulator adjustment. At these forums, we've discussed aftermarket regulators with "unusual" springs and pressure feedback. Members often return to the OEM spring to get the right pressure.
In any case, this is confirmed with a pressure gauge at the regulator. The regulated pressure should range within spec. See our forum discussions about 2.5L pressure needs and tests.
All of this could point to a dying ECU. I like your methodical approach, though, as the "parts replacement" strategy should only follow known defective parts. You're systematically eliminating faults and gradually narrowing to the wiring or the ECU. Get the fuel pressure on spec before moving to the wiring and ECU. If that doesn't do it, wiring next, then a rebuilt ECU.
Moses
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From what you describe, this is the injector pulse. The 6V range is normal, as the feed is 12V. The ECU wants to provide a ground pulse, and the switching of current is approximately 1/2 the 12VDC. Think of an alternator and its wave form.
Do check the connector just to be sure the leads are separated. Otherwise, the ECU and wiring sound okay now, and you may have "cured" that problem according to the new voltage readings.
You may have a defective injector or regulator setting. Run pressure tests at the TBI input port with a "T" fitting and port plugs for the various hookups. If pressure is high, make sure pump pressure is normal and that the return line to the tank is unrestricted for the full volume of returning fuel (not just "I can blow through it"). Narrow the troubleshooting down systematically, making sure the regulator and injector work properly and at correct settings.
You can hook a timing light to #1 cylinder spark lead and "watch" the cone spray with the timing light focused on the throttle bore of the injector with the engine running (however briefly before the engine floods). The pattern should be conical and smooth. If not, and especially if it looks like a non-atomized, distorted stream from the nozzle, there's an issue here. The timing light view of the pattern is a quick troubleshooting measure.
It sounds like you've made progress with this wire repair, there was a clear voltage drop before the latest readings. Splices should be woven wire strands with rosin core solder and double thicknesses of heat shrink insulation tubing...Good job, keep us posted!
Moses
Jeep XJ Cherokee Transfer Case Interchangeability
in Jeep® XJ Cherokee, MJ Comanche Pickup and Grand Cherokee
Posted
Thanks, Dave...Sorry the older 231 unit needs attention, you're on the right track if the rebuild is not extensive. If the fit turned out correct, your "trial fit" was worthwhile!
Would like to see the end result, your XJ Cherokee with a reliable, predictable part-time 4x4 system. The 231 with Advance Adapters SYE in our XJ has over 50K miles on it, the transfer case has many original parts, with 140K-plus miles on the Jeep. You're on the right track!
As a footnote, the NP231 can be upgraded to a six-pinion planetary gear set for more durability than the stock 3-pinion design. This is a straightforward and direct conversion, and the gear set (planetary) is readily available in the aftermarket. Something to consider during your rebuild, maybe overkill for your equipment and driving plans.
Moses