2006 M45S transmission downshift problem

[FastM45S]

Hey guys am new here but i have been a long time lurker!

I have recently bought a 2006 M45 Sport with 176k miles, clean carfax, two owner and the second owner is the one that traveled a lot and put most of those miles! Car is almost mint in and out! The carfax also shows the car was always serviced at a infiniti dealership all its life.

The transmission runs fine when in traffic, flooring it, normal driving. Sometimes i feel a very minimal bump but nothing that seems out of the ordinary. My issue is when am going at slower speeds and coming to a stop sign or yielding under a freeway U-turn, the car downshifts as i'm slowing down and as i come up on the yield and i see no traffic i give it gas (not complete stopping) and the car revs and then the gear kicks in and it hits kinda hard. Same thing for a stop, i come up to the stop and do a complete stop but right after give it gas and the same issue happens but not always. The best way i can describe it is that the car downshifts and then it kind of sits in a neutral position for second when i give it gas which cause the rpms to build and then the gear kicks in and thats why it hits. Kind of how in a standard car when you hold the clutch then let go kind of fast while giving gas. How hard it hits depends on how much gas i was giving it. I do not abuse her and she drive completely fine other that this issue.

I have not checked the transmission fluid but i dont know if that would help this issue, it doesn't do it every single time i come to a stop or slow down but i have noticed it more now that i am paying attention to it and its pretty hard to miss when it happens. Any light shed on this issue would be great! I will be calling my nearest dealer tomorrow to see if they can check it.

Also i do not have any lights on dash or any other problems! Thanks for reading!

[Partysan7]

Try resetting the ECU since you are the 3rd owner it may be very possible the car is used to be driven by previous owner... If that doesnt help then look into transmission maintnance.

[svard75]

Try manual mode and see if the same happens. If yes then it's likely the transmission needs to be flushed maybe even twice.

[FastM45S]

I will try the manual mode today to see if It does it. As far as flushing the transmission is that something the dealer has to do or I can do it? I work for a dealership and we have a shop so I'm sure I could look into it if it just involved flushing it, what type of fluid do I use?

I've never reset an ECU but would that be something that could help this issue?

[Larz]

Welcome to Nico!

If you decide to flush the transmission, Infiniti will tell you that only they have the proper fluid, but my research proved they are NOT the only source. In fact, Castrol makes 'Matic J' for Infiniti but also sells this same fluid to the public as "Castrol Transmax J". therefore, long as your shop has the proper machine to perform this flush, you can use Castrol and avoid the price of the Infiniti fluid.

Matic J: this fluid is a semi synthetic JASO 1A spec ATF actually made by Castrol and sold to nissan who then puts their name on it and slaps all the dire warnings on everything in their vehicles about it but the fluid is nothing more than Castrol Transmax J which castrol made to work in all JASO 1A spec Japanese auto trannys. JASO 1A spec is the main Japanese standard for ATF and this castrol fluid is used by nissan and subaru and is good for use in Toyota T-IV and Type T fluid requiring transmissions. This fluid has also been approved for use in applications that call for Allison C4, Dexron III, and Mercon.

Here is the Castrol data sheet to confirm the above: http://www.tds.castrol.com.au/pdf/2701_ ... 650_03.pdf

[finikM35]

Hey guys am new here but i have been a long time lurker!

I have recently bought a 2006 M45 Sport with 176k miles, clean carfax, two owner and the second owner is the one that traveled a lot and put most of those miles! Car is almost mint in and out! The carfax also shows the car was always serviced at a infiniti dealership all its life.

The transmission runs fine when in traffic, flooring it, normal driving. Sometimes i feel a very minimal bump but nothing that seems out of the ordinary. My issue is when am going at slower speeds and coming to a stop sign or yielding under a freeway U-turn, the car downshifts as i'm slowing down and as i come up on the yield and i see no traffic i give it gas (not complete stopping) and the car revs and then the gear kicks in and it hits kinda hard. Same thing for a stop, i come up to the stop and do a complete stop but right after give it gas and the same issue happens but not always. The best way i can describe it is that the car downshifts and then it kind of sits in a neutral position for second when i give it gas which cause the rpms to build and then the gear kicks in and thats why it hits. Kind of how in a standard car when you hold the clutch then let go kind of fast while giving gas. How hard it hits depends on how much gas i was giving it. I do not abuse her and she drive completely fine other that this issue.

I have not checked the transmission fluid but i dont know if that would help this issue, it doesn't do it every single time i come to a stop or slow down but i have noticed it more now that i am paying attention to it and its pretty hard to miss when it happens. Any light shed on this issue would be great! I will be calling my nearest dealer tomorrow to see if they can check it.

Also i do not have any lights on dash or any other problems! Thanks for reading!

Had that happen to me exact same thing when i was messing with Uprev tune. Its ECU problem your transmission is probably fine. Mine was downshifting hard and then would launch forward suddenly on every traffic light.