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  Topic Review (Newest First)
04-13-2020 11:08 AM
The Goblin
Quote:
Originally Posted by The Goblin View Post
Ok, so the tech at the shop hooked up the scan tool, did a bunch of tests, and quite a bit of electrical testing as well. Looks like the TCC clutch is trying to lock up but the PCM keeps kicking it back out. The clutch solenoid is working properly and the electrical connections all checked out. The scan tool showed the clutch attempting to lock up and then getting kicked back out by the PCM repeatedly. My suspicions about the PCM being replaced already (found a receipt in the vehicle for a PCM purchased last fall) appear to be false. They checked the PCM and said it looks as old as it should for an original.

So now that the gears are changed, all the codes are cleared up, and the results from the scans are in, looks like the next step is a new PCM. If a new PCM doesn't fix the problem, then we will do more in-depth testing (I can always return the PCM if it doesn't work).

Onward and upward...

Well guys, it's been a long road, but I think we finally got it. I got a new PCM, from Wranglerfix.com (great guy, definitely recommend working with him), installed it the other day, and it's never shifted so good. Lol. So far no lurching or bouncing. Hallelujah!!

So I guess my question is, did I need to change the differential gears? Or would it have been ok with just a new PCM in the first place? I'm not sure of the answer really. I do think the tires were too large for the gears based on all your feedback and the resources I have checked. So I think it was the right thing to do either way. Curious of your thoughts.

I just want to say a HUGE thank you to all of you for your input and suggestions. I have learned a ton through this process. Thanks guys! You all ROCK!!
03-26-2020 10:38 PM
The Goblin
Quote:
Originally Posted by The Goblin View Post
Ok, lol, well it was a thought anyway.

Thanks mukluk! I really appreciate your assistance. Sounds like the pressure tests you recommended are the next step then I think. I found a copy of the FSM and it recommended air pressure tests for TCC problems as well. I have a shop that I trust more than the AAMCO guys, they replaced the engine in my Volvo and were one of the only shops who would even touch it. They are a little more expensive, but they are very very thorough, so I think it's time for me to take it in to them.

You saw the video in the other thread huh? Don't think it's a flex plate? That's good to know. I guess if it's just piston slap then that's something I can live with. It's just weird that I can't hear anything from the top end, only underneath near the oil pan/bell housing. I used a stethoscope and the bottom of the engine and the bell housing was where I could hear the noise most clearly.

On to the next step then. Thanks again! I will keep you posted.

Ok, so the tech at the shop hooked up the scan tool, did a bunch of tests, and quite a bit of electrical testing as well. Looks like the TCC clutch is trying to lock up but the PCM keeps kicking it back out. The clutch solenoid is working properly and the electrical connections all checked out. The scan tool showed the clutch attempting to lock up and then getting kicked back out by the PCM repeatedly. My suspicions about the PCM being replaced already (found a receipt in the vehicle for a PCM purchased last fall) appear to be false. They checked the PCM and said it looks as old as it should for an original.

So now that the gears are changed, all the codes are cleared up, and the results from the scans are in, looks like the next step is a new PCM. If a new PCM doesn't fix the problem, then we will do more in-depth testing (I can always return the PCM if it doesn't work).

Onward and upward...
03-20-2020 12:19 AM
The Goblin
Quote:
Originally Posted by mukluk View Post
I highly doubt a cracked flex plate would cause the TCC troubles, especially so if you're not getting any fault codes.

Regarding your noise video in the other thread, it sounds like piston slap or lifter noise to me. A cracked flex plate tends to be a sharper ticking noise.
Ok, lol, well it was a thought anyway.

Thanks mukluk! I really appreciate your assistance. Sounds like the pressure tests you recommended are the next step then I think. I found a copy of the FSM and it recommended air pressure tests for TCC problems as well. I have a shop that I trust more than the AAMCO guys, they replaced the engine in my Volvo and were one of the only shops who would even touch it. They are a little more expensive, but they are very very thorough, so I think it's time for me to take it in to them.

You saw the video in the other thread huh? Don't think it's a flex plate? That's good to know. I guess if it's just piston slap then that's something I can live with. It's just weird that I can't hear anything from the top end, only underneath near the oil pan/bell housing. I used a stethoscope and the bottom of the engine and the bell housing was where I could hear the noise most clearly.

On to the next step then. Thanks again! I will keep you posted.
03-19-2020 07:55 PM
mukluk I highly doubt a cracked flex plate would cause the TCC troubles, especially so if you're not getting any fault codes.

Regarding your noise video in the other thread, it sounds like piston slap or lifter noise to me. A cracked flex plate tends to be a sharper ticking noise.
03-19-2020 10:46 AM
The Goblin
Quote:
Originally Posted by mukluk View Post
Possibly, but not very likely in my opinion. You can test the TPS fairly easily with a voltmeter if you suspect something may be wrong with it: with the ignition on and engine not running back probe the wires running into the TPS connector, see that you have roughly 5v at the OR power wire, then check the voltage on the OR/DB signal wire at idle and while you slowly open the throttle to WOT; the voltage should go from roughly 0.26v at idle and smoothly transition up to roughly 4.49v at WOT.

It's a bit of a Hail Mary, but to eliminate the possibility of some minor gremlin causing this issue you could spend some time under the hood and transmission cleaning and tightening electrical connections as well as checking for vacuum leaks. That would cost no more than a bit of your time and a can or two of sensor-safe spray cleaner.
Ok, thanks. I replaced some vacuum hoses a few weeks ago, had some pretty large leaks, but I think I got them taken care of.

I went out and drove it around quite a bit yesterday and I actually had NO lurching for the first 6-8 miles or so. I thought it had actually gone away. But, as I turned around and headed home, it started again. All this under very light acceleration because I'm still breaking in the new gears.

So here is a thought that I would really like your opinion on: I have been dealing with two major problems on this Jeep and, until last night, I thought they were separate problems that were unrelated, but last night it occurred to me that maybe they actually are quite closely related. The other problem I'm dealing with is that I think I have a cracked flex plate. I hear the typical clanking sound coming from the flex plate/oil pan area and I have tightened the torque converter bolts, so I know it isn't them. So, could a cracked flex plate affect the torque converter? Since they are literally bolted together? If the flex plate is cracked and not functioning properly, could that keep the torque converter clutch from being able to engage properly? It would make sense to me that if the plate is cracked and flexing too much that that would alter the way the torque converter spins and engages with the clutch. Also, it would make sense that it settles down as speed increases because the flex plate would be spinning with so much speed and force that the effects of a crack would be minimized.

I may be totally off, but as I'm learning about these various components, it suddenly seemed like these two problems may be one in the same.

Thoughts?

Thanks SO much for your help and advice!
03-17-2020 12:45 PM
mukluk
Quote:
... a new PCM and throttle position sensor that look like they were installed last fall. Do you think anything could have gone wrong with replacing either of those things?
Possibly, but not very likely in my opinion. You can test the TPS fairly easily with a voltmeter if you suspect something may be wrong with it: with the ignition on and engine not running back probe the wires running into the TPS connector, see that you have roughly 5v at the OR power wire, then check the voltage on the OR/DB signal wire at idle and while you slowly open the throttle to WOT; the voltage should go from roughly 0.26v at idle and smoothly transition up to roughly 4.49v at WOT.

It's a bit of a Hail Mary, but to eliminate the possibility of some minor gremlin causing this issue you could spend some time under the hood and transmission cleaning and tightening electrical connections as well as checking for vacuum leaks. That would cost no more than a bit of your time and a can or two of sensor-safe spray cleaner.
03-16-2020 11:00 PM
The Goblin
Quote:
Originally Posted by mukluk View Post
I'm not really buying the fuel filter theory due to how large the filter is (it would take quite a lot to clog it), and one would expect a filter issue to cause problems at high engine revs due to restricting the flow, not at low-medium revs like your case.

Engine coolant temp plays a role in the PCM's TCC application strategy partly due to managing the load on the engine during warmup, normal operations, and overheat conditions, but also in large part due to the fact your transmission fluid cooler is contained within the stock radiator. As such, heat from the engine coolant can and will affect the temperature of the transmission fluid, and fluid temp/viscosity has an effect upon how the transmission shifts.
Ah, ok. So the coolant does play a part in the TCC functionality, that's quite interesting. Thanks mukluk. I was looking through all the papers that were stuffed in the glove box and I found receipts for a new PCM and throttle position sensor that look like they were installed last fall. Do you think anything could have gone wrong with replacing either of those things? Since they are both related in one way or another to the TCC? Like adjustments that may need to be made and weren't, or wrong brand or something like that?

I ask about brand because I had to change an o2 sensor and I kept reading how Bosch sensors throw codes in Wranglers, and the sensor I replaced actually looked quite new; so I wonder if a Bosch was put in it last time it was replaced. So I replaced it with the recommended brand (NTX? Something like that?) and the code went away no problem. Anyway, just a thought. Trying to cover any option I can think of before I take it into the shop again to have the pressure tested like you recommended.

Also, I'm pretty sure the dealership said they replaced a cam sensor before I bought it. Those are all the repairs I know about.

I'm learning a ton with this. Thanks!
03-16-2020 12:57 PM
mukluk I'm not really buying the fuel filter theory due to how large the filter is (it would take quite a lot to clog it), and one would expect a filter issue to cause problems at high engine revs due to restricting the flow, not at low-medium revs like your case.

Engine coolant temp plays a role in the PCM's TCC application strategy partly due to managing the load on the engine during warmup, normal operations, and overheat conditions, but also in large part due to the fact your transmission fluid cooler is contained within the stock radiator. As such, heat from the engine coolant can and will affect the temperature of the transmission fluid, and fluid temp/viscosity has an effect upon how the transmission shifts.
03-16-2020 12:07 AM
The Goblin
Quote:
Originally Posted by mukluk View Post
Might be time to do hydraulic pressure & air checks.
Thanks Mukluk. The shop guy suggested a fuel filter, but that didn't seem likely to me since the problem always happens at the same RPMs. Thoughts?

So here is something interesting, I went back and re-read that page from the manual you put in your earlier post and it mentioned that one of the things affecting the TCC was coolant temperature and I just happened to have a thermostat that was stuck open so the engine never got up to temperature. I needed to change the thermostat anyway, so I changed it this weekend, took it out for a drive and the lurching problem only seemed to happen about 60-70% of the time, not every time as before.

Could that be related? I'm not sure how engine coolant could affect the transmission, so it seemed odd to me, but I did notice a change in the behavior after the engine temp was finally allowed to get up to normal. Does that make any sense at all? Or was it just coincidence?

Thanks!
03-12-2020 08:17 PM
mukluk
Quote:
Originally Posted by mukluk View Post
Outside of checking the adjustment of cables/linkages and the bands, the main diagnostic testing that a transmission shop should be doing with that trans is to perform pressure checks at various test points to see if they fall in spec or not.
Might be time to do hydraulic pressure & air checks.
03-10-2020 11:20 PM
The Goblin Well guys I need your help again. I picked up the Jeep today after getting the gears changed, and it is STILL doing the darn transmission chugging thing!

It seems like it is a little better, but that may just be my own wishful thinking. So, after changing the gearing to 4.56, it still lurches between 1500 and 2000 RPMs. I'm very frustrated with the shop because the guy at the desk I've been working with didn't even tell the technician about the lurching or to try and diagnose the issue! He just told them to change the gears. No one even drove the Jeep after they were done! And this is supposed to be the big time off-road shop in town.

So, any suggestions now? Any ideas what to check now that the gears are changed and it didn't solve the problem?
03-03-2020 02:55 PM
The Goblin Well, I've decided to just get the gears changed. I ended up getting my local off-road shop to give me a pretty good deal by matching some labor and parts quotes I got from other shops. Going to do Yukon gears, 4.56 ratio. It's heading in next Monday and Tuesday! Wish me luck!
02-10-2020 02:52 PM
The Goblin Actually just found some info on a Quadratec site that answers the bolt pattern question. Looks like YJs and TJs share the same patterns/sizes (along with a few other non-wrangler Jeeps). Thanks Kruzin.
02-10-2020 02:41 PM
The Goblin
Quote:
Originally Posted by Kruzin View Post
Those rims won't work for your TJ, they changed the bolt pattern with the JKs from 5x4.5 to 5x5.
Oh that's good to know. Was it just the JKs? Or should I stick to TJ wheels only?

I'm having a hard time figuring out what tire sizes would be ok with the 3.73 gears. All the charts I'm looking at are for manual transmissions and not for automatics.
02-10-2020 02:09 PM
Kruzin Those rims won't work for your TJ, they changed the bolt pattern with the JKs from 5x4.5 to 5x5.
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