Moses Ludel

Billybob...You provided a thorough sense for the 48RE problem. Welcome to the forums, trust you will find all of us helpful and enthusiastic, we share common interests! First of all, the 48RE was touted by Chrysler/Dodge Truck as the epitome of the A727-derivative transmissions (though they did not make that connection, the ads were more like "the most rugged O.D. behind the Cummins to date", circa 2005. I've built automatic transmissions professionally since the late 1960s. The A727 was a breakthrough in 1962 but not for 2005. When this 3-speed platform evolved into the A580, the overdrive, electronic controls, the solenoids and governor sensitivity, the weak band struts, bands and the subassembly, shaft, converter and geartrain weaknesses became the start of a large aftermarket for upgrade parts. This continues with the 48RE. I touched on this with the Sonnax discussion and article at the magazine, and Sonnax is an excellent place to see what rebuilders use to upgrade these transmissions and help them survive, even in normal use and duty. Is the 48RE worth building? Yes, they can be. The A727 was a bulletproof transmission that held up behind 425 horsepower 426 Hemi V-8s, 440 B-blocks in Class A motorhomes, and Dodge trucks to at least 1-ton capacity. When this transmission grew into an overdrive, the A580 was the earliest stab at it, and frankly, that's not the best unit, although some do build them for muscle car retrofitting to gain an overdrive. The derivative overdrive four-speeds like the 44RE, 46RE and 47RE each have some virtues, although I find their marginalized parts a bit frightening. Like these earlier versions, and granted, the 48RE is a bit better than the others, to make a 48RE bulletproof, i.e. capable of pulling a 5th wheel toy hauler with a Cummins 5.9L HO engine, does require a laundry list of upgrades. A heavy duty torque converter and input shaft are always on the priority list, the factory converter is marginal at best. For the sake of those interested, here are just a few links full of insights into the "necessary improvements" for the 48RE if you want to use it in the high performance or ongoing trailer pulling realm (same as high performance, though with less harsh shifting when the trailer is not in tow). We can begin with the quick list, several you are already considering: 1) http://www.transmissioncenter.net/dodge.htm 2) http://www.dieselpowerproducts.com/p-3832-bd-performance-48re-transmission-045-07-59l-dodge-cummins-bd1064232f-1064234f.aspx 3) http://www.atsdiesel.com/ats2/about_billet_trans.asp 4) http://www.suncoastconverters.com/shop/dodge-48re-m3ga-transmission-kit-2003-2007/ 5) http://ujue5.xspw3.servertrust.com/Dodge_performance_transmissions_s/32.htm 6) http://www.oregonperformancetransmission.com/mm5/merchant.mvc?Screen=CTGY&Category_Code=48re This last source at Oregon has a parts list of vital upgrades for the 48RE. When my turn comes to rebuild our 48RE in the '05 Ram 3500 4WD Quad Cab SRW truck (bought new and driven to preserve the powertrain, above all!), I will pay close attention to the strategic parts on a list like Oregon Performance Transmission. That said, since you're not comfortable with rebuilding the unit yourself, you can use the Oregon source as a yardstick for what parts need to be in a rebuild. Also scan the upgrade parts lists at the major shops like BDS and ATS. I would pore over the Sonnax parts, too, every last one that they recommend for keeping a 48RE alive. BDS, Banks and a host of others build the heavy-duty torque converters. Go for cost-effective but make sure all of the quality upgrades are in place. The phrase "billet replacement" is useful when you see the size of shafts (like the input) and internals. Heavy duty struts, bands and clutch units, heavy duty bushings/bearings, planets and thrusts, there seems to be no end to how an RE Dodge truck transmission can be improved, even the last one, the 48RE! Cooling is critical, the mantra with automatic transmissions, so shop coolers, too. Warranty is essential, a real "use anywhere", parts and labor assurance that you can be at Timbuktu and get some kind of recourse with the warranty. (This cleaves toward the major builders like BDS and ATS; frankly, others would be universal, local shop service contracts.) Pulling a trailer, you want a transmission that will not fail—ever, ideally—and if it does for any reason whatsoever, you cannot be "stranded" or left to the mercy of a smaller shop with standard replacement parts that would downgrade your expensive rebuild. All of this scary stuff aside, I have pulled trailers with our '05 Ram 3500 4WD, and hefty ones at times: 1) the car hauler with the XJ Cherokee on board to Moab, 2) a 27' toy hauler to King of the Hammers, and 3) lots of short hauling and moving chores, including a shop full of machinery and a compact tractor, loads in the 8,000# to 10,000# range. That's still not 12,000#, and every pound is an effort for the Dodge Ram overdrive transmissions through the 48RE. On that note, we're I to do it all again, the NV5600 six-speed manual transmission would likely have been my choice. My wife is not thrilled to drive a lifted truck with oversized tires, though the truck handles really well, and ride and stance are at least as stable as stock, maybe better. It's the size thing. That said, for me personally, a manual transmission would have been just fine. Perfect? No, they need clutches and clutch upgrades, possibly a rebuild at some point. Compared to the 48RE, though, there would not be the factor of just plain expecting to do a rebuild—inopportunely in your case. (I'd be a bit less surprised; having seen the inside of my 48RE when I did the Sonnax valve body and accumulator piston upgrades, I've dispelled any illusions.) I'm expecting the 48RE and converter to require a major overhaul or upgrading somewhere between 180K-240K miles, even with the utmost of care. The stock profile seems just too marginal. I respect your approach and would suggest price shopping the best equipment and most refined rebuilding methods, balancing and blueprinting included in the build, a quality valve body upgrade, essentially all of the rebuilding techniques that include the best parts while addressing each of the 48RE's weaknesses. Again, make a checklist of Sonnax, ATS and BDS approaches, each has a great deal of experience with these units. Please let us know what you decide to do. Also, check out my steering gear and linkage exchange with Megatron, you'll be doing that upgrade before this is all over. As a footnote, I'm very happy with my decision to change axle gearing to 4.56 when 4.10 would have solved the bigger tire diameter issue. The 4.56 gearing with 34.6" (35") diameter tires works nicely and takes a load off the engine and transmission. Slight increase in engine piston travel per mile, but that will prove negligible if the engine goes 490K miles instead of 500K. Actually, the engine might last longer with less strain and decreased need for turbo boost and higher cylinder pressures. I geared for anticipated trailering, a conventional pull travel trailer in the 6,000#-7500# range. Thanks for joining us, Billybob! Looking forward to our exchanges... Moses

Pleased to add comments and assist...Checking the timing by the factory method might help, it's electronically controlled, so follow the official Mopar procedure for setting the base timing. Good you're getting the pressure testing equipment, you'll demystify the regulator and other issues, Josh, and Harbor Freight seems like the cost-effective tool source in this case... The source for the PDF on the TBI adjustment is a 1989 Mopar Service Manual for Jeep. Should be reasonably accurate on all counts. Check under the regulator bowl for signs of an adjuster screw, a mirror might help. If possible, avoid the need to unbolt the TBI unit again. Moses

You're taking a scientific approach, Josh! Good troubleshooting and observations. Sounds like a new TPS was necessary, and you're in the ballpark on its configuration. There were many overlapping issues here, and you have done a terrific job of working through the maze. Your experience is a gem for others. Started with a dirty fuel tank and displaced sock, many replacement parts thrown into the mix along the way, plus problems that crossed paths and caused real confusion. You inherited a "nightmare" by some estimations, I think this is all worthwhile in the long run, as you'll end up with a much more reliable and predictable Jeep Wrangler. You're now replacing defective parts without "guesswork", and this is way up the learning curve. Your engine's current running condition sounds much easier to troubleshoot, Josh. You may have a clogged fuel filter at this point, and the dripping injector is a concern. I'm confident that you'll nail it this round. I'm still of the opinion that a fuel pressure/volume check at the inlet to the TBI would be useful. Your Harbor Freight tester idea makes perfect sense, you don't plan to use the tool day in and day out, so this would be the right approach for the current project. We haven't discussed the TBI pressure regulator setting. This is adjustable, and I have provided the steps in the PDF below...The test and adjust does require a pressure tester, so again, the Harbor Freight kit makes sense. You want the right fuel pump pressure and volume of fuel flow. You want the correct regulator pressure setting (14-15 PSI tested at the TBI regulator test port shown in the PDF.) The injector needs to flow fuel on closed loop commands. The cold start/warm-up enrichment needs to work, the system needs to drop into closed loop at the right stage...If the fuel filter is clogged, you might get sufficient pressure without volume, so volume is important, too. On that note, you would be able to check volume more safely at the regulator test port, as the pressure is much less than the fuel pump supply pressure. Be careful here, this is gasoline! A "T" into a large coffee can or gas can could be helpful, with key on/engine off during the test. Set regulator pressure before checking volume flow. Adjusting the regulator pressure might solve the fuel drip from the injector. 2.5L TBI Pressure Settings.pdf Thanks for having the patience to push through on this—especially in an apartment workspace! If you had sublet the project to a shop, you'd be unsure of the long-term prognosis and would be out a good deal of money by now. By fixing this yourself, you are very aware of 2.5L TBI troubleshooting, and others are benefitting from your experience and gained knowledge! I'm sure they are appreciative of your efforts, findings and strategies... As a footnote, Josh, if you find that the inlet fuel pump pressure is too high for the regulator's range, there are inline fuel pressure regulators available from Summit Racing and others to drop down the incoming pressure—without restricting flow. Another concern with the TBI system is the return line to the tank. If the return line is pinched, clogged, kinked or otherwise restricted, the fuel pressure at the regulator and port will soar. If you have normal inlet pump pressure and very high test port pressure that cannot be dropped by adjustment of the regulator, suspect a restriction or obstruction in the TBI return line to the fuel tank. Check hose routings! On your TBI system, the pump pressure goes directly to the TBI pressure regulator, and the TBI regulator has to buffer whatever incoming pressure exists. Incoming pressure, therefore, is very important, and we discussed the pressure range for the pump earlier. Test to confirm... Moses

The factory method looks for a percentage or ratio as indicated in the PDF...If you followed the steps, you're getting useful feedback! The TPS (Throttle Position Sensor) is like a rheostat or potentiometer: as the throttle valve opens, the voltage goes up proportionately, engine idle being a specific baseline voltage. This signal is crucial for the A/F ratios, idle performance and to achieve a balance throughout the EFI system. Since the TPS gets a real workout (consider the switching cycles here!), this is often a trouble spot on higher mileage EFI engines! If you can narrow this to a defective TPS switch by accurate testing, you've hit the mark! If you confirm the TPS failure, you have a very tangible source for the trouble you describe...Sometimes, the TPS can be adjusted, but if it is finicky and not holding an adjustment, it's defective. This is what I like about mechanical things. There's always a reason why they work or don't. (Human beings are more complicated.) Keep us posted, Josh! Moses

Try the TPS and other tests, this could narrow it down. With all of the changes in fuel pressure, a new pump and regulator and so forth, there could be room for a TPS adjustment or ISA setting...WOT is simple to confirm. We always like it when there is something concrete to address. You've found several sources of trouble lately, Josh, on the right track! Moses

Lean or like a timing issue? Possibly, Josh...However, I'd check the TPS voltage reading. This device is adjustable on the 2.5L four. Unstable idle and bucking could very well be remedied by a simple TPS adjustment or repair. Don't rule out the ISA motor adjustment. Might as well check the WOT adjustment, too! To demystify this, I've copied the 1989 factory manual information on adjusting each of these devices for a 2.5L TBI. Open the PDF for details! Jeep 2.5L TBI TPS ISA WOT Adjustments.pdf Moses

Wow, that spring comparison is graphic, thanks for the photo! The wire size on the smaller spring must be 1/4th the apply pressure...Apparently, there was excessive fuel pressure, and the leaking or by-passing regulator was "force feeding" the injector without the normal electronic opening and closing of the fuel flow. Good observation, and good solution...Let's see where this leads now that the engine is flowing a more moderate amount of fuel. We'll see if the sensors are all back on line with normal closed loop function and air-fuel ratios. Moses

Has been running very rich, and the oxy-sensor may be sooty, too. Could pay to remove the O2 sensor and clean it a bit, at least inspect it and wipe off soot. The engine has been through the ringer with over-rich mix, you're likely sorting out the impact of all that fuel flowing through. Spark plugs could also be sooty at this stage... As for the "injector still works when unplugged", that's a good one. Makes me want to run a pressure check of incoming fuel pressure to the regulator. If this over-fueling persists, the regulator may be unseating from too much incoming fuel pressure, which I hinted about earlier. Time for an actual fuel pressure test on that inlet pressure to confirm the fuel pump output? I'd check the spark plugs and oxygen sensor for soot... Moses

Happy Thanksgiving to you, friends and family, Josh! You're going to have a very reliable '89 Jeep YJ Wrangler 2.5L four-banger when this is all done... Moses

Oh, boy! Did you flush out that fuel tank? I've seen more "troubles" with fuel tanks and gunk since the ethanol era. Left to its own devices, ethanol damages plastic screens, dissolves things like pickup socks, clogs motorcycle (and automotive) carburetor jets and passageways, you name it! Maybe corn farmers made it big on the ethanol bonanza, consumers certainly didn't... So, you're back on the repair trail and narrowing the fix here. Good job, Josh! Thanks for sharing the photos, quite graphic! Looking forward to the next update... Moses

I was about to ask if you changed the filter...The sudden stalling and inability to start could have been a filter issue at that point. If the filter was bad enough from sucking debris off the tank bottom, it may have disintegrated and clogged the pressure regulator. Recall, you did have one point where the removal of the regulator and reinstalling it seemed to help...I commented that the pressure regulator may have had a clogged passage that cleared. Debris like you describe, from either the sludged tank or a filter coming apart, could create fuel flow issues or clog the TBI fuel inlet, pressure regulator or ports/passageways within the TBI unit. As professionals, we don't like to borrow trouble, right? So, my approach is always systematic and aimed at eliminating immediate symptoms. Here's what I would do now: 1) Confirm fuel pressure from the pump, making sure it is within the 27 PSI or so maximum. 2) If the pump pressure is correct, I would verify fuel pressure past the regulator. It must be limited by the regulator to 14-15 PSI. 3) Once you have uniform fuel flow at the regulator in terms of volume and pressure, turn to the passages in the TBI unit, between the pressure regulator and flow nozzles. 4) An often overlooked sensor that can create a lot of trouble is the crankshaft position sensor at the back of the engine on the upper bellhousing. Oil and debris can cause this sensor to malfunction or work intermittently. Many overlook this as a trouble spot and chase after other issues. It takes only minutes to access this sensor, remove it, and clean it thoroughly with spray carburetor cleaner and a rag. If in doubt, do an ohms resistance test on the device. Make sure you do not have too much fuel pressure past the regulator. If pressure is high, determine whether this is a pressure regulator malfunction or a fuel pump with excess output pressure. You had many times that the engine ran well then suddenly went into some form of fuel flow failure: too little, too much, etc. Note: At this point, with all of the flooding, the oxygen sensor and catalytic converter may be overloaded. You may need to clean that up to restore a normal idle and closed loop functions. Overall, though it costs for diagnostic equipment, you likely could benefit from a search for DTCs. A DRBII or aftermarket scan tool (Snap-On or OTC Genesys) with hook-ups for the Jeep TBI era could prove helpful. Any code reader that would hook to your diagnostic plug could at least retrieve stored codes from the ECU. Look for an inexpensive code reader for your pre-OBDII era Jeep. I'd be surprised if you have no stored codes at this point. I would clear the codes and get a fresh read, as there could be several sets of stored codes with some problems already remedied. At this point, I'm thinking a dirty crankshaft position sensor, high fuel pressure or a fuel pressure regulator malfunction. Functions of the ECU typically work or they don't; seldom do they work intermittently, which makes me think in terms of a "mechanical" device rather than electronic. (I would, however, check wire connectors for corrosion and contact integrity.) As you share, you've exhausted a variety of sensor possibilities, not to mention your wallet, chasing this around. Onboard diagnostics and fuel pressure tests can demystify and at least confirm or eliminate trouble spots. Stop the flow of money over the parts counter until you're absolutely certain you have a malfunctioning part... Unless you've exhausted your tools or patience, there's much to be gained by following through. Be systematic like your heavy equipment repairs and troubleshooting. When you do find the culprit and fix it, you'll have far more trust in the Jeep. Moses

Josh, before you throw in the towel, let's look at this objectively. You had no spillage or flooding issues before you changed the pump. You have severe flooding issues now—and are likely in limp home mode as a result. The 2.5L fuel pump for a 1989 Wrangler is a Walbro 550 or Chrysler 83502995. Here are the 2.5L TBI pump specs: 1989-1990 Jeep Wrangler Fuel Pump 4 Cyl. 2.5L (E) E.F.I. OE spec Walbro electric fuel pump and installation kit fits directly into any 1989-1990 Jeep Wrangler 4 Cyl. 2.5L (E) E.F.I.. Detailed fuel pump installation instructions included. Made in the USA. Fuel Pump Specifications Walbro Part Number: 550 Minimum Current: 12 Volts Operating Pressure: 17 PSI Minimum Flow @ Outlet: 28 GPH Low Pressure Fuel Pump Location: In-Tank Now, let's look at a 1991 2.5L MPI fuel pump for a Wrangler. It will fit your tank fine, as '87-95 tanks are similar. This is a Mopar pump #04637193. Here are the specs for the Walbro common equivalent: 1991-1993 Jeep Wrangler Fuel Pump 4 Cyl. 2.5L (P) E.F.I. (Chrysler #'s 4637192 & 4637193) OE spec Walbro electric fuel pump and installation kit fits directly into any 1991-1993 Jeep Wrangler 4 Cyl. 2.5L (P) E.F.I. (Chrysler #'s 4637192 & 4637193). Detailed fuel pump installation instructions included. Made in the USA. Fuel Pump Specifications Walbro Part Number: 5CA234 Minimum Current: 12 Volts Operating Pressure: 65 PSI Minimum Flow @ Outlet: 24 GPH High Pressure Fuel Pump Location: In-Tank Note the obvious pressure output differences for these two pumps that look similar. The '91-up engine is MPI and operates at 31 PSI (regulated) injector pressure. Your '89 TBI operates at a 14-15 PSI (pressure regulated) setting. If you put the later pump into your tank, you will be pushing 65 PSI against a TBI pressure regulator designed to operate with a 17 PSI tank pump pressure. This is likely your newly developed flooding problem. My hunch: The new pump supplied is for a '91-'93 MPI engine, not your TBI application. If you run a pressure check on the pump-only, you will likely turn up a 65 PSI output pump. This would over-pressurize the TBI pressure regulator and cause flooding. Check the new fuel pump part number and run the number at www.fuelpumps.com. This is where I came up with pump output ratings for TBI versus MPI engines: http://www.fuelpumps.com/-c-0/19891990-jeep-wrangler-fuel-pump-4-cyl-25l-e-efi-p-2212.html http://www.fuelpumps.com/-c-0/19911993-jeep-wrangler-fuel-pump-4-cyl-25l-p-efi-chrysler-s-4637192-4637193-p-2210.html Before dropping the tank again, I would run a pressure check of the fuel pump (before the regulator, pump-only pressure). If you are confident this is the wrong pump, either by the part number or actual pressure tests, drop the tank and replace it with the correct, 17 PSI output pump. Let us know what you find here...TBI and MPI requirements are dramatically different... Moses

Hi, David, thanks for joining the forums, we value your participation! In a nutshell, you cannot make this work. The AW4 has the 4.0L bellhousing pattern, the 1994 2.5L four uses a different bellhousing pattern. So, this AW4 will not bolt up to your 2.5L engine. Though rare, there were automatic-equipped XJ Cherokee 2.5L models, but they use the 904/999 Chrysler 3-speed automatic. Chrysler likely borrowed this setup from the YJ Wrangler. If you're sold on the idea of an automatic, the AW4 is the transmission of choice with its overdrive and track record for durability. You would need to place a 4.0L inline six in front of this transmission. For your '94 model XJ, that's a full-on swap due to engine mounts, radiator and other needs. It might be easier to find a popular 1987-up 4.0L XJ Cherokee with AW4 as a base for a new project. This would be cost-effective in the long run. Happy to bat this idea back and forth... Moses

Really good news, Josh! When you have time, post some pics of your '89 Jeep YJ Wrangler at the 'Tech and Travel' Forums...Looking forward to your posts...Welcome! Moses

All interesting, sounds like the first regulator had a plugged passage or flow. The trip up to 3000 rpm should have cleaned things up, and you did do a removal and replacement of that first regulator (now in place again)...You'll know in the morning, also whether the MAT ohms rating will work...Moses P.S.: If this does work out, great...Otherwise, you're back to the drawing board...Clogged or blocked passage would be the only explanation for a "cure".

Josh, I read the post at the Jeep Forum/link. The Jeep owner used a Wells unit that also fits a later application. It sounds like your approach has its match. If your ohms readings are correct for the '89 specs I furnished, you bought the right sensor and simply needed to modify the wiring...See my comments about soldering, your best assurance of ohms integrity. We should have reverse engineered the switch by ohms rating in the first place then sought out a two-wire replacement sensor with the right thread pitch and ohms readings. Apparently, Chrysler and Renix MAT sensors have reasonably close ohms tolerances, maybe other applications, too...Good job, Josh! Moses

Gotcha, Josh...Can see the plug and wiring differences. Suggestion for your use and others: When working with an EFI system, I use solder for splices and cover with multi-layers of heat shrink tubing, enough tubing to emulate the insulation strength at the wires. EFI circuits are hypersensitive to ohms resistance, and with a sensor like the MAT, Josh, ohms resistance accuracy is critical. When we use a butt connector and crimp approach, there's a lot of room for ohms mismatch. The crimp, by design, simply cannot lock all strands of the two wires together. Also, vibration is clearly an issue with any automotive application, more so with a Jeep 4x4. I always use rosin-core solder on electrical splices like this. Flux helps, easier in the core so you can solder steadily. Consider soldering, it's really quick in the long run, and you'll take the guesswork out of ohms resistance. (Crimping can often work okay for trailer lights and such, I still prefer solder.) Another very good feature of heat shrink, when done properly, is to prevent corrosion wicking up the wires. A 4x4 Jeep gets wet, let's face it, that's what a Jeep does! So, preventing water from wicking up wires will go a long way toward eliminating corrosion over time. Again, a good reason to use rosin-core solder and heat shrink tubing! As a footnote, when I bring the two wires together for soldering, I face the stripped wire ends toward each other and try to lap and interlace the strands evenly. Solder can fill tiny gaps and secure the wire joint together. Keep strips of heat shrink well up the wires, away from heat, while soldering. Then slide the heat shrink into place and shrink it. Wooden matches (move quickly or hold away from the tubing) work well for me when shrinking the tubing. Use care not to melt through plastic! I know the joint is laced and soldered properly when the finished "bulge" is minimal. Moses

Let's see what that MAT does...You'll check ohms range first...The carb cleaner usually turns up leaks. We'll stay after this, there's always a reason for the hunt-and-peck idle! Moses

Regarding the rough idle, have you tried finding a vacuum leak? Have you changed the PCV valve? Back to the Seafoam temporary fix, the PCV valve could be involved...The valve is a routine replacement service part. Moses

These are all national brands and available product lines, whether the specific part numbers are still active is another story. Try the NAPA number at your local NAPA store. See if Rock Auto carries any of the other lines, and if so, whether they can furnish the part from their Warehouse Distributor sources. There are way too many numbers here to strike out...eBay might be another source, Josh. Also, check the individual product lines, as most should have an online catalog at their official website. Search by part numbers and manufacturer at Google. See if that yields anything...As for the part you ordered, the oddball 1991 Dodge Monaco 3.0 V-6 listing suggests that some Chrysler engines were still using this MAT after 1990. Moses

Josh, if you do get the later MAT, you need to compare the ohms settings and make sure they're right. 1991 is definitely an MPI engine, not TBI, Chrysler discontinued TBI after 1990. Here is the OEM Mopar part number for your MAT sensor: 33002382 SENSOR, Intake Air Temperature This part also fits a 1991 3.0L Dodge Monaco V-6. It has been discontinued by Mopar. However, I found this remarkably lengthy cross-reference chart courtesy of a Google Search. Verify the cross-reference. The Chrysler number above is from my set of Mopar Catalogs and is reliable. If the part numbers below do cross over (verify before buying), we can thank "Hornbrod" at the Comanche forum http://comancheclub.com/topic/30054-where-to-get-a-mat-sensor/ for this effort: AIRTEX 5S1004 AUTO-TUNE PT9599 BIG A 53-1009 BORG WARNER WT5502 CHRYSLER 33002382 ECHLIN TS5016 FILKO CS-62 GP/SORENSEN 779-19015 KEM 139-411 NAPA TS5016 NIEHOFF TS81351 NIEHOFF WA629EL STANDARD/HYGRADE AX9 TOMCO 12120 WELLS SU330 Let me know what works here. If you decide to set the ISA, I have the OEM specs, let me know... Moses

Josh...Glad to see your follow-up, I'm focused on your second post as possible ties to your problem. For openers, you're absolutely right, the engine will not come out of cold start mode if the IAT is out of sync or the engine coolant temperature is off. Jeep constantly emphasized a 195-degree F thermostat to assure adequate temp for the closed loop mode as you comment...Definitely replace the thermostat unless you suspect that the gauge is inaccurate—I like to use a surface temp IR tester to check the actual temperature. You can temperature probe around the engine block, at the radiator, hoses and, importantly, at the thermostat housing. As for testing the IAT (actually called the manifold air/fuel temp sensor or MAT), here are the specs for your '89 TBI system: Degrees F Ohms 212 185 160 450 100 1600 70 3400 40 7500 20 13500 0 25000 The two adjustable features on your TBI are 1) the TPS (throttle position sensor) and 2) the idle speed actuator motor or ISA. Have you adjusted either of these devices? Moses

Thanks for the compliment, Josh. The TBI signal could be a factor, although the Seafoam has me looking at the oxygen sensor, EGR valve or an exhaust obstruction...The '89 YJ Wrangler is early OBD and awkward for testing the onboard diagnostics. If you do have access to a scan tool that will work with Chrysler's early OBD hookup, try getting a DTC trouble code from the ECU. You do have a diagnostic test plug on the Jeep engine bay wiring. Make sure that the exhaust is unrestricted, and consider the EGR valve and oxygen sensor. Test parts before replacing them. Even though the oxygen sensor is a higher mileage "perishable", you should still make sure that it is defective before buying a new O2 sensor. Same with the EGR valve. As the issue goes away when you sweep Seafoam through the vacuum hoses, this may be a clue. Seafoam flows through the combustion chambers and exhaust, which may be cleaning a sticky EGR valve or dirty O2 sensor. Unseated and stuck open, the EGR will generally cause a rough idle or low speed performance quirks. An EGR valve stuck shut will create upper cylinder heat and possibly erratic fuel mixtures. The EGR controls NOx and can affect other exhaust gases. Considering your troubles to this point, the EGR valve would be worth testing. If you have a hand vacuum pump, you can quickly test the EGR with the engine idling. Attach the pump hose to the EGR. Pump down vacuum with the engine idling, enough to open the EGR valve. You should hear a change in engine speed and smoothness as you open the EGR valve at an idle. No changes would indicate that the EGR valve is either stuck or defective. The valve has a diaphragm that can be weak or leak with age. Be cautious when working around the EGR valve, it gets very hot! Handle with care...If you attempt to remove and clean the EGR valve, do not soak the diaphragm in solvent or carburetor cleaner. Try to submerge the base of the EGR valve (metal parts only) in carburetor cleaner, and make sure you get the valve plunger to open and shut freely—and seat completely. Rinse away any solvent or carburetor cleaner before reinstalling the EGR valve and running the engine. Moses

Fred, sounds like a VSS possibility...Check the wiring and connections to the vehicle speed sensor. Check wiring in general. The coming to a stop issue could be the lockup converter staying locked, and this might also be a VSS problem. Before replacing parts, look for the simpler fix around the VSS: wiring and connections. If the VSS tests defective, replace it. As for shops at the Tahoe Area, I suggest Levrett Transmission at Reno on E. 4th Street. They are a multi-generation family business, and the E4OD is a mainstay for this rebuilding and troubleshooting shop. Levrett Transmission enjoys a good reputation locally: Levrett Transmission 832 E 4th St Reno, NV 89512 (775) 323-6151 http://www.levretttransmission.com/ A chat with the Levretts by phone might cast some light, they work on the E4OD day in and out, especially Ford F-trucks. Keep us posted, Fred... Moses

Hello, Fred, welcome to the forums. Sorry to hear you're stranded away from home. Let's see if we can target that problem and get you home... From what you describe, at worst this could be a more serious direct clutch or center support assembly issue, which would require a teardown/rebuild. Before jumping to that conclusion or testing hydraulic and mechanical components, I would check the PCM for any stored codes. Loose or damaged electrical connectors, defective SS1 or SS2 shift solenoids, loose or damaged vehicle wiring, the PCM module itself or the vehicle speed sensor (not likely the VSS, as the problem is only on 2nd/3rd shift) can each create shift issues. There is a specific set of diagnostic codes related to the E4OD transmission malfunctions. See if a code is stored already and run the diagnostic sequence for the PCM and the transmission specifically. I can provide a list of mechanical/hydraulic trouble spots for the E4OD if you cannot find a simpler electrical or electronic issue. The SS1 or SS2 solenoids or wiring circuits could be an issue; electrical problems can be fixed without a teardown. If no electrical, PCM, wiring, VSS or solenoid issues exist, and if you do need to tear into the E4OD, the likely cause of this 2nd-3rd shift issue is the valve body, 2-3 shift valve, an SS1 or SS2 solenoid or circuit malfunction, a damaged center support assembly, overall wear or a faulty direct clutch assembly. In any case beyond the valve body and solenoids, major work would be involved. Always attempt the simpler, in-chassis diagnostics and fixes first...Do not drive with the transmission "slipping", as severe damage will occur rapidly. Let us know what you find. I'm here for any additional help. Looking forward to your participation at the forums... Moses