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Discussion Starter #61
The torque converter will lockup around 10-20 MPH for fuel efficiency, then unlock at that speed to allow the CVT to slip enough to come to a stop and not move forward, like pressing a clutch pedal in.

However, it look like yours is still unlocked @ 79KM at operating temp in your second screenshot, I would expect it to be locked-up at this point... Maybe this is the cause of the over-taching?

BTW, you can change the units in the settings to MPH, unless you're more familiar with the metric system...
It's strange how the torque ratio only showed "LOCK" that one time during the entire day of driving. It was locked from 5MPH-47MPH for a duration of about half a mile. Since I wanted to see if it would clear, I slowed to nothing and it finally cleared at 10MPH. So you're saying it should always be locked at 1.00?

Yes, I realized later morning that I could change the unit of measure to U.S., and changed it. But thanks.

I"m going to shoot some footage of CVTz50 during the cold start drive this morning and review it later. During the five days of using CVTz50, I've never seen the torque ratio LOCK except for that one time yesterday.
 

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Search for lock-up in the CVT section of the service manual. It mentions lock-up occurs between 11 MPH to 25 MPH.

It also mentions a lock-up solenoid valve and a lock-up clutch, maybe yours are faulty...
 
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Discussion Starter #64 (Edited)
Thanks for the info, MOSL03. I Googled a few things and did some light reading. It still may be related to the DTC'd secondary pressure solenoid valve, coupled with a dirty filter, coupled with mixed fluids, etc. While tempted to replace the step motor while I have the pan off, there's no guarantee doing so would solve anything, and if the pressure solenoid is still an issue after new fluid and filter, then it would seem the valve body needs to be replaced, so there's no point doing things piece by piece with a CVT valve body that has over 280,000 miles on it, 45K of which were problematic for it.

The torque converter isn't locking up more often than not. In fact, I'd say it's not locked 95% of the time. Since fluid pressure is key to its proper function, I think it's likely the mixed type and differently aged fluids are the problem. I just pulled the upper intake and throttle body to do some cleaning and gasket replacements, and I decided to replace the plugs, coils and PCV valve while having access, to ensure everything's in top shape once the CVT situation is refreshed. I removed, checked and cleaned most of the electrical connectors and sensors and such. Looking forward to seeing how things end up...

Have you ever used CVTz50 for the idle relearn procedure? I've started it about ten times and it gets stuck on step 2 of 3 for at least five minutes before I finally give up. When I turn off the ignition and restart the car and enter the app, it says the relearn was successful, but the RPMs are still around 930. I don't understand why there isn't a setting to adjust the idle down. In that app, all you can do is increase the RPMs by a minium of 25. I'll probably just disconnect the NEG batt lead and do the relearn manually. I'd like my 500RPM idle back. :)


EDIT: I've tentatively concluded that temperature is the problem with the TC not locking up. I noticed that when the engine temp is below 172F, the TC won't lock. Once it gets above 172F (typically after being parked while running for a few minutes) and I proceed to drive it locks, then once the engine temps drops below 172F, it unlocks. I'm guessing it's two possibilites... 1) The different fluids in the CVT are all heating slightly differently, creating cold spots in the fluid and not triggering the TCM to engage the lock-up clutch to lock the TC. 2) The CVT fluid is cooling too fast due to my engine's thermostat being stuck open most of the time, so the tranny fluid running through the radiator isn't experiencing any normal hotness from the engine coolant being hotter to help keep the tranny fluid temp nominal for the CVT to operate properly. It's kind of a stretch, but I think it makes sense. Factor in Winter driving where the past few days the temps have been in single digits, and that further cools everything and prevents engagement of the lock-up clutch and locking of the TC.
 

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I haven't tried the idle relearn, never had too... I can't recall anyone else mentioning whether it worked for them or not...

There's another thread where they performed the manual idle relearn, and it resets after restarting the engine similar to what you mentioned when using CVTz50... It will be interesting if it sticks when you perform the manual idle relearn method...

I agree, I wonder why the app only allows adjusting the idle speed up, not down too... Have you tried any of them? Maybe they are mislabeled and are really down not up... I and @assad have found the developer very responsive to questions, you may want to email him.
 

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Are you using throttle body and MAF sensor cleaners that are labeled for such use? I have heard the MAF sensor is particularly sensitive to the wrong cleaner being used...
 

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Discussion Starter #67 (Edited)
I prefer to use Scrubbing Bubbles toilet bowl cleaner to clean throttle bodies - I think it does a more thorough job. Yes, I'm using the proper TB spray. :) This happened the last time I cleaned the TB around 2014/2015...I lost my low idle. I think I just disconnected the battery and did the relearn again and it took. Today, I tried the CVTz50 relearn again and waited 11 minutes and it still got stuck on step 2 of 3.

I think something is causing the torque ratio to now lock because, until three days ago, I'd never gotten these semi-violent "release jerk" sensations with this CVT. My guess is, either it's not been locking correctly for years and something I've done recently has made it start to lock/unlock (e.g. MMO)... Or, it's been locking'unlocking all along, but the blown front motor mount is probably getting worse, and the released tension of the TC is making the motor mount smack against metal and create the sensation. It was pretty bad twice today, as it locked at random times at 25MPH while under cruise and the car would kind of buck a little. Sometimes, it wouldn't unlock until slowing to 5MPH. It's also possible the MMO is creating problems with certain aspects of the drivetrain process. I don't really think it is, but it's always a possibility.

Yes, I tested some of the RPM adjustments in CVTz50 and they are working correctly, and I can't manipulate the menus at all to reveal a possible second menu of options for an idle adjustment decrease. I might contact the app's creator and ask a few questions. I know there's a newer version, but according to some reviews the latest one isn't great if using on a Nissan CVT. I think my version is 1.50 or 1.52. It appears there is a place to give manual commands, but I need to figure out the proper syntax and structure. Maybe there's a way I can instruct MO to idle down a bit.

Using the app, I disabled engine braking for about 50 miles, and discovered that I really miss it when it's not active. The car coasts nicely, but it forces me to increase brake usage, which I don't care for.

EDIT: After removing the NEG battery lead, reconnecting it, letting the car warm up, turning off the car and doing the CVTz50 relearn, it now idles around 812. I think I'll do it again, but next time I'll do it manually to see if I get the same results.
 

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Discussion Starter #68 (Edited)
It looks like MO's torque-locking issue is due to a sticking thermostat. During the Summer months, I'm guessing the TC is locking up fine. During Winter, that sometimes stuck open thermostat will prevent the engine from reaching normal operating temperature which will prevent the torque converter from locking up. When I'm stopped and at idle for five minutes, the engine temp will get above 172F and when I start to accelerate, the torque converter will lock. As soon as the winter air starts cooling off everything and the engine temp drops below 172F, torque lock vanishes. I've had a sticking thermostat for about three years (probably due to the liquid aluminum used for the leaking cooling jacket), and I have a new one in the spare tire area...I guess it's time to change it out. One thing about the "slip rev" category.... I watched a YT clip where a Nissan Sentra owner shows the CVTz50 in action, and that car's slip rev is just like mine at 127+. So I'm thinking that the info supplied with the app about that setting hovering around zero is incorrect. Or maybe that person's CVT is also screwed up.

Here's a clip of some lock/unlock situations, along with screenshots showing what does and doesn't allow for torque lock and over-taching. If both engine/CVT temp are listed as OKAY, MO will get torque lock and have no overtaching. If engine temp is at least 172F but CVT temp is only WARM and not OK, MO will get torque lock but will have over-taching issues until the CVT fluid gets up to temperature. The CVT temp readniess triggers OK at 122F. The CVT temp triggers HOT at 192F. I intentionally tried to get the CVT hot to see what temp it would trigger at.


UPDATE: Even if eng/cvt temps are statused as OK and MO is all warmed up, I will occasionally get what I call "slack acceleration," where when I push the gas pedal the RPMs and acceleration don't align with the position of the gas pedal as I've known it all these years. I feel that's primarily related to P0868. Also, I very carefully pressure-washed portions of the engine and components, and was careful not to spray directly onto electrical connections. I kept the engine running during washing. About 20 minutes later, MO threw a CVT code for the secondary speed sensor. I wonder if there's a bad wire somewhere...I thought I was pretty thorough when I inspected everything, but you can never see everything unless you take everything apart. Interesting that I'd get that part producing an error. It's hasn't come back in two days of driving.

As for the idle relearn, I decided not to disconnect the NEG battery lead again and instead drove MO until hot, parked, turned off the engine, fully depressed the gas pedal and the backed off about 1/2" and held it there while starting the CVTz50 idle relearn procedure. I turned the key to position 2, the app paused at step 2, I released the gas pedal, started the engine, the app processed the final steps and the idle has hovered around 700. Since I replaced the spark plugs and coils when cleaning the throttle body (and I did not down-gap the plugs like the past few times) it's possible my idle isn't going to be in that 500-550RPM range anymore.
 

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Discussion Starter #69 (Edited)
Over the past two days, I've been getting a lot of over-taching when accelerating from a stop (even after driving for hours), and MO ended up throwing P1778 twice while simply moving forward on a level surface. It's the first P1778 I've gotten in a think about two weeks. Monitoring the CVTz50 data, I noticed that the SEC pressure readings started to align better, while the PRI pressure readings were far apart and reducing below 1.00 a lot. I also noticed that the STM Step reading that usually has the numbers mirroring each other (e.g. 196/196) were sometimes mismatched (e.g. 185/186).. Since MO was no longer making progress and I'd gone about 4,000 miles since infusing the MMO, it was a perfect time for something new, so I replaced the fluid and filter. It's was snowing after completing the work, so I haven't gone on a test drive yet...

To help purge the fluid, I started the engine once, then used the CVTz50 app to disable all six cylinders so the engine would turn over but not start. I cranked the engine over about six different times after each time seeing the fluid stop coming out.

 

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Discussion Starter #70 (Edited)
Mixed performance. Still had over-taching the first day, but after warmed up things were fine and some aspects had improved, such as a cold start up a hill without letting the car warm up. Day 2, I thought the CVT was done, since things had changed in a bad way. Later on, the P0868 that's been persistent in triggering immediately after beling cleared, and that has been popping up on the TCM since using the CVTz50 app, finally cleared and stayed off, even after driving very aggressively on the highway.

I drained some fluid from the pan to see how things looked (refer to end of video). While I didn't see any shavings, I did notice a lot of murkiness. It might be that aspect of the fluid that's causing such inconsistent performance. In a couple of weeks I plan to drop the pan again and check the magnets and filter to see how things look, provided MO is still running. I realize with the amount of large shavings found in the pan, the CVT's days appear numbered. So, though I might indicate I'm going to replace a step motor if such and such is resolved, I've since decided it's not worth it.

I also believe I misread some of the CVTz50 info. If you look at the attachment "step4 pressure," there's a result from an automatic pressure test performed on the system whenever in D and stopped. It's that data that I believe refers to what I was saying about pressure of .7 being target, .5 a warning and .3 a failure. So, if I'm understanding things correctly, my pressure test at that time averaged .53, which is basically at mimimun and at the warning level. Yesterday, the highest result from that pressure test was .58.

EDIT: The video is wrong...I didn't throw P1715 and P1778 yesterday when going up that hill, I threw P1715 and P0128.

 

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Discussion Starter #71 (Edited)
Today, things started okay, went to better, then ended worse... Pressure test early on was averaging .58. Later, it went as high as .63. (.70 is target, .50 warning, .30 failure). After sitting for two hours and restarting, the STM Step reading "196/196" kept flashing yellow, despite a cold start drive immediately up a steep hill where MO drove perfectly. It wasn't until I came to a stop for about 20 seconds that the pressure test was performed and showed a warning level of .48 as min. and .51 as avg. It remained at .48 for the next 1.5 hours of driving back from the mountains. Had some minor over-taching when accelerating from a stop, but MO drove fine and felt fine.

Checked the CVT fluid level several times during the day, and it was fine. So now I have a few thoughts for tomorrow... Overfill the CVT by a quart and see what happens. Add a quart of MMO to see if the thickness will increase pressure to normalize things. Get some NS-2 to see if it has the ability to cure the low pressure issue. I'm back to getting the P0868 persistently. Acceleration and speed are fine...just the minor over-taching and flashing 196/196 while taking off.

 

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Discussion Starter #72
Added a quart of CVT fluid last night. Morning pressure was .063/.063 then tapered off to hold around .56/.58. After getting gas, I noticed the PRI reading dropped to .20 for a split second at idle, then floated around .35 until I got on the gas. Later in the morning, there was a large gap between minimum and average readings, and I knew something was wrong at .50/.58. Later, pressure readings were .48/.57. Ended the day with .50/.53 and with P1778 always popping up instantly while driving back from the auto parts store with CVT cooler filter and CVT pan filter/gasket in hand. I've also been noticing the past few days that the battery charging sometimes drops to 12.94 briefly while cruising, and usually hovers around 13.30 and maxxes out at 13.67. Since the battery is more than three years old and I'm always using electronics equipment and draining it, I might grab a new one tomorrow to make sure my CVT issues aren't due to a failing battery.
 

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I would think you'd be seeing a higher charging voltage if the battery was marginal... The alternator regulator would need to put out a higher voltage to charge the battery...
 

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Discussion Starter #74 (Edited)
Since the charging readings in the app have been very erratic lately with wild swings (particularly below 12.90), I took a few minutes to grab the serp belt out of the spare tire area and I installed it tonight. The old belt was nearly six years old, but had no cracks, tension was good, it wasn't glassed over or making any noise, but it had a ton of miles on it and I thought it might somehow be slipping and causing the inconsistent charging. I'll find out tomorrow morning if the new belt did anything to solve that issue. It could also be because I pressure-washed the alternator about a week ago to get off all the dark grime and residue from a coolant leak.
 

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Discussion Starter #75 (Edited)
I would think you'd be seeing a higher charging voltage if the battery was marginal... The alternator regulator would need to put out a higher voltage to charge the battery...
Auto-electrical has never been my strong suit, so maybe I'm not understanding what the CVTz50 app is telling me. I have two readings...the first seems in realtime and is always fluctuating (e.g. 13.18, 12.94, 13.41). The second reading typically never changes and usually reads 14.40v. I thought the second reading was telling me what the alternating was putting out, and the first what "realtime temporary storage" my battery was able to achieve while being fed from the alternator. I thought that "RTS" was supposed to always remain above 13.60 in order to effectively supply power. Since it wasn't holding that minimum voltage, I thought the battery cells may be losing their ability to retain that short-term storage, thus my considering a new battery. In driving around today with the new serp belt, my cruising voltage has typically remained above 13.41, and more or less floated between 13.41 and 13.85. In prior days, it was floating primarly in the range of 12.90 to 13.33 and sometimes hitting 13.41.

Coincidentally, for the first time in a few days, my pressure readings have improved instead of degraded. The only time those pressure numbers dropped today was immediatlely following an undercarriage rinse, and I noticed the RTS reading had dropped to 12.86. About an hour later, the pressure numbers actually improved from where they started off in the morning, and I noticed the RTS reading was floating above 13.41 Could still be a ground wire issue or crud on the alternator wiring or whatever. Not sure if it's just coincidence that pressure improved a tad after messing around with the charging system. I'll probably pull the alternator wires and clean up all the contact areas and recheck that new ground wire to the chasis.

EDIT: So I really should have read the app details more thoroughly, instead of just skimming them and skipping over some. Looks like the "battery" info is this: "Battery – TCM power supply voltage and voltage on OBD2 socket, V" I guess it's not displaying what I thought it was.
 

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Anytime you're reading battery voltage from a control module it's always going to be what that control module is getting, not the voltage at the battery terminals. If you want to approximate the battery terminal voltage then you can hook up your multimeter to the battery terminals and observe the average difference between the battery voltage at the terminals and the scan tool voltage (e.g. scan tool reading is on average 0.3 volts less than the actual voltage at the battery terminals). Once you have that adjustment factor then you can drive around and have a reasonable idea of what actual alternator output is from your scan tool while you're driving.
 
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Discussion Starter #77 (Edited)
Thanks, coffee. I kind of lost sight of that fact that I'm using an app created primarily for transmission functions. I'd definitely get a more accurate voltage reading taking it directly from the source.

All in all, the pressure numbers varied little today and MO drove fine. Min. reading never dipped below .55, and max avg. was .63. I'll wait another day to get some readings before doing anything else. Trying to do one thing at a time and then put some miles on to see if there's any change.

I've been monitoring some dark, oily fluid in the coolant reservoir the past few days, and I'm trying to determine if it's a blown head gasket or a problem with the radiator and tranny cooling lines that are creating the problem. Engine oil looks perfect and tranny fluid looks perfect, and all fluid levels look normal. At the moment, I'm leaning towards it being tranny fluid leaking within the radiator and rising to the top and getting pushed into the reservoir . Maybe that Autozone-bought radiator is junk.

EDIT: I think a quick way to elminate the transmission fluid as the source would be to disconnect the tranny cooling lines and unite them with a barbed union to bypass the radiator for a few days. But then it hit me that the CVT cooler has coolant running to it, and there could be contamination happening there. Might also have to disconnect those coolant lines and join them with a union to bypass the cooler. UPDATE: It smells like motor oil, so it's more than likely a blown head gasket.

QUESTION: Could that old internal CVT leak that I stopped by plugging up the weephole be the source of my current line pressure problem? Say fluid used to make it past the seal (or maybe even an internal housing crack), and over the years that standing fluid in the weephole chamber sealed the leak. Is it possible that pressure can be lost through that area despite no fluid coming out, which could affect line pressure? Or is that just not mechanically viable? Does line pressure not create or impact any internal housing ("gearbox") pressure?
 

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QUESTION: Could that old internal CVT leak that I stopped by plugging up the weephole be the source of my current line pressure problem? Say fluid used to make it past the seal (or maybe even an internal housing crack), and over the years that standing fluid in the weephole chamber sealed the leak. Is it possible that pressure can be lost through that area despite no fluid coming out, which could affect line pressure? Or is that just not mechanically viable? Does line pressure not create or impact any internal housing ("gearbox") pressure?
What weep hole are you referring to? Those are only used to allow for the visible presence of oil (or some other fluid) in case an external seal is leaking. On the CVT, the only weep hole that comes to mind is the one near where the CVT and transfer case mate to let you know if the transfer case and/or CVT output shaft seal are leaking.
 

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Discussion Starter #80
I'm not sure if you've played with them, I noticed CVTz50 has built in charting function, and also data logging that can be exported to an excel spreadsheet.
I did do some logging, but my version of Excel is from Office 2000 and won't properly open the app's data file, even with the upgrade converters. I could probably open it in Google Docs, if Google still offers that feature.
 
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