After 180K miles and 18 years, I solved my WJ Jeep's cold shift flare. It took 5 minutes.

Joined
Dec 11, 2016
Messages
174
You can probably tell that this really annoys me. Vehicle is a 99 Grand Cherokee 4.0 with the 42RE transmission. It has always had a 1-2 shift flare when cold where it would shift out of 1st into neutral and it would take about 5-15 seconds before it would shift into 2nd. Sometimes it would cling in 1st until 3-4K rpm before going into neutral and blipping the throttle might get it into 2nd gear after a few seconds. Not very safe when cold and driving from stops or hills but it would shift fine when warmed up.

I bought this Jeep more than 18 years ago at around 76K miles from a Chevy dealership in GA. Before my test drive the group of salesmen redlined the car to warm it up faster to hide the problem. From that experience, I will never buy another used car from a dealership again. It was sold as-is, and I drove it home out of state.

ATF+4 changes didn't help, I thought it must've been a faulty seal in the transmission or a pressure problem with solenoids or governor sensor. But I didn't want to take the transmission apart or throw multiple expensive parts at it without knowing the exact failure so I decided to drive it as-is until it fails. 18+ years and 180K+ miles went by and one day the trans seemed to start in 2nd gear and slip. It wasn't exactly in limp mode. It wouldn't shift into 3rd until at high rpms and releasing the throttle. I tried to drive it home and on the way it set a P0720 code: output speed sensor circuit.

According to a WJ website, it's a somewhat common failure among the early years of the model. Many years ago, I remember that I searched for the cause of the shift flare hoping it wasn't the actual transmission, I tested the trans output speed sensor with a multimeter which seemed to test ok. This time, I tested it and it seemed like it wasn't working. So I bought a new one from RA ($5 + $3 shipping). Replaced it and refilled a quart of ATF+4 that dumped out when removing the sensor.

Now, the trans shifts fine even when cold. After all those years, after all the wasted gas in neutral and high revs, after years of annoying drivers behind me expecting me to accelerate but the car's hanging in neutral, after time spent chasing whatever suggestions I found from searching WJ forums... it was an $8 part that took 5 minutes to change. After 18+ years and the Jeep has 260K miles still with its original transmission. $8 plastic part. Come on, Chrysler....

I'm disappointed it wasn't a more 'worthy' failure. That sensor only failed a little bit when cold and didn't fail completely so I couldn't trace the problem with my limited car repair experience. Most searches seemed to point towards a transmission seal problem. So, anyone else having shift problems with a 42RE car, consider the output speed sensor among your other suspects.

Any of you guys solved a long-term problem that turned out to be something stupid simple? Is there some way I could have tracked down this problem years ago before the P0720 code?
 
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The Check Engine light on my 95 F150, which remained lit for five plus years, was a leaky "coffee can" in the underhood vacuum system. I fixed it for free. Diagnosis was a hassle with it being OBD-I, and an uncertainty over whether it had 2-digit or 3-digit codes in the test-light-in-jumper-harness diagnostic mode. But, TL;DR, EGR wasn't working like it should have been.
 
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Jun 11, 2003
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706
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Hedgesville, WV
I have a 2003 Dodge Ram 1500 that started throwing a P0440 Evap code about a year after I bought it new. Took it in and they replaced the gas cap, it seemed to work but as soon as it got cold out it came back, took it in again and they replaced a purge valve, The next cold snap and it came back. The third time they replaced a hose and you guessed it, When it got cold it came back. After that I lived with it for 14 years. I bought a code reader and cleared the code and took it in for emissions inspection in warm weather. 2 years ago I decided to knock some rust off the frame and paint it before it got bad. While I was under the truck I notice these clamps that look like zip ties on the frame mounted valve to the gas tank. They were all broken but still in place. I pulled them off and replaced them with hose clamps and my P0440 has never come back. 3 trips to the dealer and nobody noticed the plastic clamps were broken. I will say if I had not been working on the frame I would not have seen them either because they are on top of the valve. only took 17 years to find.
 
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after time spent chasing whatever suggestions I found from searching WJ forums
forum.jpeg


Seriously though, you don't really expect to find real help on forums, do you? They're meant for entertainment, socializing while staying anonymous, bragging, and passively aggressive venting.

If I did everything I "learned" on forums, I wouldn't have a single functioning vehicle left by now. So just chill and enjoy the entertainment, lol. Far and in between, you will get good advice, but it's hard to filter it out because of all the other noisy people.

I'm glad you solved your problem, and thank you for posting your solution. It might help someone else one day, that is, if they have the patience to read and don't get distracted.
 
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Aug 13, 2017
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WY
Reminds me of the joke about the old timer who sold firewood for a living getting his first chainsaw.
 
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Aug 23, 2010
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pa
many posters never post the cure, BUT thanks to those that DO!! it can help others presently or even later when a similar issues arises + that IS what forums are for as they are not FAKEBOOK forums, just good info with some discussion included!! i enjoy BITOG a lot + having various sections like when i learned about MVNO's for cell phones i never realized existed + now have Airvoice!!
 
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Nov 30, 2004
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2,517
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SD
When we got married, my wife had a 96 Intrepid 3.5. I had an identical car, and I'd always noticed that hers cranked a bit longer than mine before starting, but otherwise ran great. We planned to take her car on our honeymoon (from SD to the coast of SC), so I wanted everything in top shape. Being very busy with wedding planning/preparation, I dropped the car off at a very reputable local shop, and told the owner to see what he could find. He diagnosed a bad fuel pump module (wouldn't hold pressure when shut down), replaced it, and declared it fixed. However, I immediately noticed that it still cranked exactly as it had before: not excessively, but a little longer than mine did. I wrote it off as "that's just the way it is", and quit worrying about it.

A few years down the road, I was working on the car (something unrelated) and pulled the fuel pressure regulator (can't remember exactly what I was doing or why I had to remove the regulator). This regulator had upper and lower o-rings. The lower o-ring was missing...I'm guessing possibly from the factory! So it never leaked fuel externally, but without the internal o-ring, it couldn't hold pressure. With that replaced, it started instantly, just like my car always had.

1624370725678.jpg
 
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Aug 13, 2017
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2,717
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WY
I bought a 1976 Ford Grenada with the 351W in 1980. It always got terrible fuel mileage. Around 1983 I have the hood popped and the engine running checking the tranny fluid when the wife asked about the "Rainbow". I had no clue what she was talking about. She finally pointed out that around the bottom of the car in front with the sun shining she was seeing a rainbow. Long story short, the vent hole on the fuel pump was putting out an extremely fine mist of fuel. I would every once in a while smell fuel around the car but it took the perfect lighting conditions to see it. Changed the pump and immediately noticed a jump in MPG. Nothing spectacular but maybe a couple mpg. 3 years and 40 thousand miles later.......adds up when you are making a buck and change an hour in the military.
 
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View attachment 61104

Seriously though, you don't really expect to find real help on forums, do you? They're meant for entertainment, socializing while staying anonymous, bragging, and passively aggressive venting.

If I did everything I "learned" on forums, I wouldn't have a single functioning vehicle left by now. So just chill and enjoy the entertainment, lol. Far and in between, you will get good advice, but it's hard to filter it out because of all the other noisy people.

I'm glad you solved your problem, and thank you for posting your solution. It might help someone else one day, that is, if they have the patience to read and don't get distracted.
I solved quite a number of problems by reading forums
 
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Apr 9, 2008
Messages
14,989
Location
Central NY
My Taurus had a terrible problem with pinging when I got it. I spent a lot of time and money trying to fix it. In the mid 00s here, there really weren't any good OBDII techs so even the dealer techs (while it was under warranty) would just fire parts at it. It had all sorts of things done to it - both by the shop and myself.

We tried everything from reprogramming the computer to taking out the thermostat, colder plugs ... just couldn't get anywhere with it.

Then it finally threw a code near the end of its life for the DFPE sensor. Replaced that and it never pinged again.
 
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Aug 21, 2013
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4,257
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Central Maryland
I agree. However, in my experience, the ratio of useful information to information that can get you in more trouble is not even close to even.
Yes, you have to sort the wheat from the chaff. But I fully understand your position- too much bluster and bragging.

I've found the most useful information on vehicle specific forums (sorry BITOG), like the Honda Blinking "D"/5-speed shift sensor replacement, which saved me beau coup time and money.

In the "Years later category", I owned an old Cougar with the 351W engine and a bent frame. I bought a Firestone alignment coupon book, took it in for alignments for years, and over the years replaced every ball joint, suspension bushing and tie rod end, yet it always had loose steering. The poor techs hated to see me coming, because it was a b**** to align, and I would do all the work and bring it back for completion. But they got their revenge in another way.

Finally I was under the car while doing another procedure and the person in the driver's seat turned the wheel, and I saw where all the slack came from- the P/S hydraulic double valve thing that the ball sat in. I bought a new one for over $400 and put it in, for the first time ever I experienced steady tracking and instant steering response.

A few months later I junked it with bad heads, slipping transmission and almost 200K miles. The transmission had already been replaced with a junkyard unit, the heads had been rebuilt before (I pulled/replaced and machine shop rebuilt) and I knew they didn't have enough valve seat to grind left in them. I junked it, not worth fixing.
 
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Feb 16, 2010
Messages
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Location
PA
Yes, you have to sort the wheat from the chaff. But I fully understand your position- too much bluster and bragging.

I've found the most useful information on vehicle specific forums (sorry BITOG), like the Honda Blinking "D"/5-speed shift sensor replacement, which saved me beau coup time and money.

In the "Years later category", I owned an old Cougar with the 351W engine and a bent frame. I bought a Firestone alignment coupon book, took it in for alignments for years, and over the years replaced every ball joint, suspension bushing and tie rod end, yet it always had loose steering. The poor techs hated to see me coming, because it was a b**** to align, and I would do all the work and bring it back for completion. But they got their revenge in another way.

Finally I was under the car while doing another procedure and the person in the driver's seat turned the wheel, and I saw where all the slack came from- the P/S hydraulic double valve thing that the ball sat in. I bought a new one for over $400 and put it in, for the first time ever I experienced steady tracking and instant steering response.

A few months later I junked it with bad heads, slipping transmission and almost 200K miles. The transmission had already been replaced with a junkyard unit, the heads had been rebuilt before (I pulled/replaced and machine shop rebuilt) and I knew they didn't have enough valve seat to grind left in them. I junked it, not worth fixing.
do not despair of the chaff hiding the wheat--
all together we know more than any one of us.
sharing our experience is guidance for examination and observation, not confirmation of facts before the evidence is found
chaff-sorting and flailing is a mechanics stock in trade- every client has a story and we NEVER know the (REST OF THE STORY) firsthand facts until WE look.

RCFA is a solid procedure but its not always easy. in its purest form it is nearly infallible but not often inexpensive or easy.
fundamentals are FUNDAMENTAL, FUNDAMENTAL, FUNDAMENTAL. ((repeat that until you find a teacher thats smarter than fundamentals.)
the RCFA end product is the billboard for how to fix, and what is ITS root??
FUNDAMENTALS!!!!! --- faith in FACTS and the knowledge of the conditions that present them.
a 6th grader can conduct an RCFA fault tree transit (sakichi toyoda explained it) but it takes a MECHANIC to know how to find the facts to answer his questions.

computers fix nothing. they can automate adaptive systems to changes, but they only tell us how to look for facts.
motorcycles, boats, planes, bicycles, heavy equipment to lawnmowers, hydraulics, pneumatics, mechanics, materials failure characteristics, digital and analog engine systems, ALL have their physical performance limits and their signalling characteristics.

as the pentateuch teaches- its there for those who have 'eyes to see' and 'ears to hear'.
being successful at that practice today includes cultivating a personal mindset open enough to cope with human fallible presumptions, and the will to use all possible diagnostics to SEE and HEAR.
thats why we speak here, and listen here.

stay safe- be well

BE of strong heart - Every day is a classroom and FATE and FACT can change us from highest teacher to lowest student in the blink of an eye.
(the idiot in my mirror has proven it to me many times, I hope the MECHANIC in your mirror is a lot smarter.)
 
Joined
Mar 2, 2004
Messages
2,954
Location
Kentucky
I solved quite a number of problems by reading forums
Same here. Forums that are brand and/or model specific have no substitute. Nowadays seems Youtube is getting more popular for the DIY crowd, but I prefer forums.

Most vehicle problems I encounter are common issues that affect a certain model due to engineering deficiency or flawed/cheap parts. So chances are, dozens of people have had the same problem. A half hour spent searching a forum will usually lead me right to the solution.

And they are an absolute gem for maintenance type work, as all advise/posts apply to the same engine/model/etc. that you happen to be working on.
 
Joined
May 5, 2017
Messages
15
Location
W.Ga
(OP). Well, it’s about 13yrs too late for me!
I had a 1994 Jeep Grand Cherokee w/5.2L that did almost the EXACT SAME THING!
It didn’t present itself as bad as yours, but would surge/slip shifting 1-2 under hard acceleration. I always thought it was something as you discovered!

I too bought the vehicle used with 35,000mi in 2001. It had 235,000 when I traded it off. I had also used it to pull a travel trailer. Never found metal or anything else when changing fluid.
 

01rangerxl

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Birmingham, AL
I chased a bizarre stalling problem on my 1994 Ranger 4.0 for years. I noticed when I got it the truck the coil had been replaced with an aftermarket one and a new connector had also been spliced in, but didn't think much of it because it ran well...most of the time. It started stalling on me when it got hot outside and I had been driving the truck a while. It would need to cool down for hours, but after that would start and run fine. There were some OBD I codes sometimes, but they were not much help and pointed me in the direction of the computer itself. I pulled it out and the inside was filthy. After making sure I could get another, I decided to try cleaning it with connector cleaner, and miraculously it seemed to work for a time. At some point I also put in a brand new Motorcraft ignition module. I just didn't suspect the coil itself because the truck ran great until it would just buck a couple times and cut off.

Then some time later, the same thing. It seemed like adding gas helped with restarting, so I thought maybe it was a vapor lock type issue, plus the filler neck was trashed and I figured it was a good time to go over the fuel system. Basically ended up semi restoring the whole back of the truck's frame since I had the bed off. New Motorcraft pump and everything. New rear taillight harness NOS from Green Ford. Everything.

I get it back together, and it runs like a brand new truck, until it freaking stalls again. The last time I had it towed for that particular issue ON THANKSGIVING, the tow truck driver wound up being a habitual Ranger/Explorer owner as well. After describing the issues, he said "man I bet it's the coil, mine did the same thing." I put a new Motorcraft coil on it, and it never stalled again. It did have plenty of other issues after that, but I'm glad I at least beat that one.

Funny thing is, after my 4 door 94 Explorer was wrecked, I went to TN to look at an Eddie Bauer replacement. It ended up being a little rougher than I wanted for the price, and had a stalling issue. The sellers were forthcoming and showed me the repair orders from the shop they took it to. The shop threw a MAF at it, then said it needed an engine due to low compression after it stalled again. I drove it, and it didn't need an engine. I told them about the coil issues on my Ranger, but decided to pass on the Explorer because there were a few too many things that needed attention. They messaged me weeks later and said they had replaced the coil, it had fixed the issue, and they had a buyer but wanted to give me first offer. I had bought my 97 by then and didn't have time to make it happen, so I told them thanks and they sold it to the next buyer. I don't regret taking a day to go look at that truck, and am glad I helped keep it on the road.

When I went to get my current '94 Explorer an hour plus away, my biggest mechanical question for the seller was does it ever stall? I also had a new Denso coil with me. 🤣
 
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