[adiadrian]

I´ve read on the forum about the CVT limiting the rpms after a long drive at high speeds. I noticed that my CVT when driving over 180km/h (190 to 195km/h (my MO does 195km/h max)) for a few kilometeres started to limit the rpms to around 3750rpms. When I try to push the rpms higher I can hear the engine and also the rpms fluctuating, usually between 3300 and 3900rpms. Then I also noticed this rpm fluctuation at those high speeds, which means everytime this happens that when I take off my foot from the gas pedal the rpms are again restricted to the 3750rpms.

I talked to my mechanic and he recommended me to install a cooling system (practically a simple cooler that the Europan MOs have as standard) for the CVT oil, which I did. Now I can stress the CVT more than before, i.e. drive for a longer time above 180km/h. However when I drive at these speeds I get a very strange effect from the CVT. The rpms remain high at 6000rpm, but the speed of the car decreases if I even lightly take off my foot from the gas pedal - from 180km/h to even 120km/h. If I press the accelerator again the CVT whines, but does not seem to convert that energy into speed, ie. the car does not accelerate and the rpms fluctuate again. I then have to drive at 80 to 100km/h max for a couple of kms to be have the CVT functioning normally again.

I know that 180km/h is fast but in Europe, especially Germany where there is no speed limit on some motorways, people do drive that fast. I had a BMW X5 before the MO with a 3L Diesel engine and just 212HP. The X5 could do 210km/h and it was not a problem for it to keep that speed without the gear box going on strike. From a 3,5L engine I can accept the 195km/h speed limit - I would expect it to do the 210km/h, but how is it that it can not keep the speed of 195km/h. Is there something wrong with my CVT?

Please understand the mechanics in Europe still do not have much experience here in Europe with the MO/CVT as the MO only came out last year, so reccomendations to go there will not help.

I now have 82000 km of mileage and also an LPG (Propane and Butane) gas installation on it. Running it on LPG is around 35% cheaper than on petrol and the car has more power.

 

[RayH]

I'd be curious if the you have the same acceleration problem if instead of letting it drop from 180km/h to 120km/h, letting it drop to something like 100km/h or lower before trying to accelerate back up to speed or letting of the throttle completely before trying to accelerate again.

My guess is that it's probably a software quirck in the way the cvt is controlled relative to throttle position and speed. You're probably driving in a range that the software was not otimized for.

 

[adiadrian]

rpm fluctuation a software error? To whatever speed I drop it to does not matter. If I drive at high speed I still get the rpm fluctuations and what I am saying is that I would like to keep that high speed and not let it drop.

 

[Eric L.]

Maybe its actually a speed governor?

 

[njjoe]

adiadrian-

My guess would be "self-preservation". I think the engine/CVT is limiting the speed to protect itself. Maybe even with the tranny cooler there is still a heat problem during an extended hi-speed run.

-njjoe

 

[adiadrian]

Self preservation could be it. But is it normal that the rpms fluctuate? I would expect a bit more from a car with a 3,5L engine. Speeds of 190km/h should not be problem for it. Has anyone had experience after changing the CVT fluid whether it improved the way the CVT functions?

 

[Eric L.]

I'll say it again - the RPM fluctuations sounds a lot like you are hitting the fuel cutoff for a speed governor. I know European MO's are supposed to be a little faster than US MO's (we are governed by the stock T-rated tires here, 118mph), but I don't know by how much.

 

[njjoe]

adiadrian-

Did you always have this problem or has has it just recently started?

You indicated in your first post that you modified your MO by installing an LPG system. That is a pretty significant mod. Is it possible the LPG set-up is the root-cause of the problem?

-njjoe

 

[Gonzo]

I remember when I hit top speed on the MO the RPMs where "touch" in a sense that minor changes to the gad pedal would cause the RPMs to want to change. I thing the CVT is just trying to be more effiecient than anything else. As soon as you remove gas pedal need the CVT wants to come down.

I would be interesting to try to hit top speed again in the MO in Ds... could be a different animal.

 

[adiadrian]

Gonzo - driving in Ds stresses the CVT even more and the rpms are therefore limited even quicker.

Eric L. - the speed limiter hits in at 195km/h. The CVT when stressed limits the rpms to 3750 and I get the fluctuations at anywhere between 120km/h and 195km/h. When the CVT cools down I can drive normally without the rpm fluctuations. So no it is not the speed limiter.

njjoe - LPG has to do with the fuel that is being delivered to the engine. The rpm fluctuations I see more a problem with the CVT rather than the engine. Another aspect is that with LPG I can still switch to normal petrol and the same effects (fault) occur.
The CVT is stressed more at higher temperatures. I drove it last winter and this is when i bought it, and I had no problems back then.

I see your point with the self preservation cause when the I drive "slowly" the rpm limitation and fluctuations do not occour, or after this happens I drive slowly - I think the CVT oil cools down then, and I can stress the CVT again. However for me there seems to something wrong as such a car I would expect to be able to keep the high speeds without the CVT going on strike.


Someone in the forum mentioned once about CVT fluctuations but I can't find that thread anymore. I think that there is something when the CVT oil reaches high temperatures. Maybe there is a mechanicla part that needs to be changed. Has anyone seen any improvements in the way the CVT works after changing the oil? CVT working quieter? Being more efficient?

 

[Eric L.]

Hmmm an interesting point regarding the CVT being the limiting point. Have you checked your CVT fluid level yet?

120kmh is not even 80mph. There should be absolutely no reason why the vehicle should hesitate or feel unresponsive at those speeds. Did you try checking for possible codes?

 

[njjoe]

adiadrian-

My guess is that the problem you are experiencing is definitely heat-related, because you indicated after the tranny-cooler was installed you were able to drive at high speeds for a longer distance before the engine/CVT began to act up. Did the tranny-cooler provide a significant improvement?

There appears to be two separate oil to water heat exchangers for the CVT. One connects to the radiator while the other connects to the heater hose. So obviously the engineers knew that heat would be an issue with the CVT.

Is it feasible to install a tranny cooler with a larger capacity? Or to put an additional cooler on the second circuit?

I'd like help you solve this problem so I will know there is a MO out there cruising the Autobahn with the big-boys!

-njjoe

 

[adiadrian]

Eric L. - CVT fluid level is ok, as I had to add CVT Fluid after installing the cooler. Codes I can not check as the Nissan dealer is pretty incompetent concerning the Murano - they even do not have the service manual. My mechanic who has the service manual does not have at the moment the software to read the codes. So unfortunately I can´t check them yet.

njjoe - The cooler definately improved the functioning of the tranny. Come to think of it you could be right with there being a second circuit that needs to be cooled. As now after the transmission cooler I get mostly the second effect (see my first post in this thread): namely keeping the foot on the throttle keeps the rpms high but does not convert the rpms to acceleration. A slight reduction in throttle causes the speed to drastically decline.
My guess is that the tranny cooler cools only one part of the transmission and that is why I can keep the rpms higher for longer periods. The second circuit might not convert the rpms into speed as it is not properly cooled. The question here that arises is where is the second circuit!??

thanks for the support and please keep it up, so I can finally drive normally

 

[adiadrian]

Seems like changing the CVT fluid and reseting the tranny has solved all problems. My dealer used NS-1 CVT fluid. Can someone please tell me if it will harm my CVT?

 

[Eric L.]

Seems like changing the CVT fluid and reseting the tranny has solved all problems. My dealer used NS-1 CVT fluid. Can someone please tell me if it will harm my CVT?

I thought the CVT took Nissan NS-2 fluid!

Read this and call your dealership to confirm immediately!

http://www.nissanhelp.com/Ownership/Bulletins/Nissan/2002/NTB02-114.htm

 

[adiadrian]

That is what I thought so too and it is also specifically written in the manuals to only use NS-2. My dealer does not know what the difference between NS-1 and NS-2 fluid is.

 

[Eric L.]

That is what I thought so too and it is also specifically written in the manuals to only use NS-2. My dealer does not know what the difference between NS-1 and NS-2 fluid is.

NS-1, from what I can tell is the fluid for the smaller CVTs used in 4-cyl engines on other Nissans. NS-2 is the CVT fluid used on the V6-mated CVT in the MO, Maxima, Altima, etc... - since the bulletin says NS-2 must be used, I would insist they switch the fluid.

 

[adiadrian]

Eric will NS-1 harm the CVT in the Murano?

 

[Eric L.]

Eric will NS-1 harm the CVT in the Murano?

I'm not a Nissan engineer so I cannot say for sure, but if you read that TSB I linked above, it does say that you should *only* use NS-2. I think an official Nissan document like that is enough to convince me that NS-1 is probably not a good idea.

 

[njjoe]

Seems like changing the CVT fluid and reseting the tranny has solved all problems. My dealer used NS-1 CVT fluid. Can someone please tell me if it will harm my CVT?

adiadrian-

What makes you say your dealer used NS-1 fluid? Hopefully he did use NS-2 fluid and simply jointedly wrote NS-1 on the work order.

Either way I would contact your dealer ASAP and question him. If, in fact. they did use the incorrect fluid I would demand that they purge the incorrect fluid and replace it with the NS-2. I would also demand that they provide me with an extended warranty on the CVT.

Let us know what you find out.

-njjoe