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Hey guys I might just be silly but I never owned a automatic transmission vehicle before. I have a 2003 g35 auto sedan with some bolt ons pop charger, plenum spacer, berk high flow cats, stillen exhaust, and uprev tune by seymore4. when I'm cruising along say 40mph not on the gas then I press gas alittle it jumps 500rpm before I feel any pickup when I let off it drops about 500rpm before I feel engine brake. I'm in the manual mode most of the time. Once it jumps that 500 rpm then the rpms match the speed better. Idk if that is normal for auto or is that it slipping transmission. Also I feel like when I get on it the rpm goes close to 6000rpm and takes a few seconds to get to the next gear. Like I said I'm used to manual so idk if that's normal. Thanks for your input guys. I do gotta say with the bolt ons the cars alot faster and seymore4 was great with the tune.
As I understand it, the best AT Mods are the Transgo valve body mod, 3.9 gears, torque sense diffy and a tune. Good safe mods.
A good thing to do is swap out the transmission fluid with OEM only. Other equivalent fluids have temperature range performance issues. I learned that the hard way.
The lack of crispness and delay you feel, I believe, is normal for the OEM transmission...but the car is my wife's car...so I am no G35 expert..
I also wouldn't jump straight to the 3.9 gears, stock 5AT is 3.3 and most folks start by picking up a 6MT VLSD with the stock 3.5 gears. It's going to raise your highway cruising rpm by going with steeper gears and the 3.9 you're sitting at almost 4k rpm going 75mph. If you have an AWD then you cannot swap gears.
I am using max life atf from valvoline that's where I work Maybe change out the fluid for oem stuff might help I did put Lucas transmission non slip and it feels a lot better I think it might just be a worn out transmission possible
When in doubt just add a bottle of friction modifier to your transmission fluid, it's better for it to engage a little quicker rather than slower and slipping the clutches.
Don't add the entire bottle all at once though, start with 1/4 of the bottle. Then add another 1/4 if you need faster engagement, keep adding until you feel the shifting is nice and firm in all throttle positions.
Since you've already added aftermarket fluid it's pretty difficult to swap back to OEM Matic-S since a fluid drain/fill only exchanges 1/4 of the total volume. Thus the friction modifier will probably need to be used if it feels like it's not engaging quick enough.
EDIT: The manufacturer uses a very specific amount of friction modifier to make the transmission shift the way THEY want it to shift which for a luxury car is typically a little on the "smooth" side. Personally I prefer a fairly firm shift so all my AT vehicles have extra friction modifier added to them except for my Tacoma because it makes it a pain in the snow. The rest of my vehicles are basically summer only, towing, etc so the quicker the engagement the better as long as it's not jarring the cabin.
I have a 2 quick questions what brand or type of friction modifier should I use also I put Lucas transsmission non slip in already a whole bottle. So I used maxlife atf for a whole year no issues. Then I changed my transsmission filter and added whole bottle of Lucas and topped up with maxlife atf again no issues. Now I did some work on the car radiator brakes ect.. once I put plenum spacer, pop charger, ztube, hfc, stillen exhaust and uprev tune I noticed it slips more at high rpm shift about 5-6k. I driven cars with bad clutches that's kinda what it feels like. Maybe the little extra power is alittle much for the transsmission. This is also my first auto transmisson car I owned.
Are you re-checking fluid level once the transmission is hot, if it's 1/2 quart low it's going to feel like it's slipping.
A quick search of the product sheet for that Lucas transmission stuff it doesn't appear to be a friction modifier, I'm guessing it's just a stronger detergent to keep the SOLENOIDS clean. Stuff like this can actually have the opposite effect by more effectively cleaning friction surfaces on vehicles. You've added two bottles, 1/4 of the previous bottle was removed during the last drain/fill, so basically you have 1.75 bottles of that stuff still in your transmission...
As for the Valvoline Maxlife, I definitely don't recommend it for Asian transmissions. Yes it says on the bottle it's MaticS compatible however it's pretty well documented that nearly all Asian transmissions use a higher friction coefficient fluid compared to US vehicles and these "one size fits all" fluids aren't actually good enough to do the job. ATP makes a friction modifier additive that you can use, ATP-203. I'd just add the entire bottle at this point, it will help counteract some of the smoothness from those two bottles of Lucas ATF treatment.
If you don't want to shell out the money for actual Nissan MaticS fluid then run Idemitsu type S. It's been long speculated that Idemitsu is actually the OEM manufacturer for that fluid. These transmissions are pretty notoriously documented about shifting weird when people start adding non Nissan Matic J or S fluid. Literally 20 years worth of threads about it here on these forums alone. No one has complained about the Idemitsu Type S though since it's probably the exact same fluid as Matic S.
Going forward I would do a transmission drain/fill every time you do an oil change, switch back to actual OEM Nissan Matic S or Idemitsu Type S, you can buy the Idemitsu in a gallon jug or quarts.
So to recap,
-Add a bottle of ATP-203
Do the next ATF fluid change early, the sooner the better, drive to see if it's better (right now you're blended about 50% Valvoline with 50% Nissan fluid, first change will get you back to 25%V and 75%N roughly).
If it's still slipping then add a second bottle of ATP-203
If it's still not shifting properly then schedule ANOTHER fluid change, easiest if you just line it up with your next oil change, This will get you to like 15% valvoline, 85% Nissan fluid.
You also don't need to replace the filter in these transmission, it's more of a large particle screen and not actually a fine filter. It's good for the life of the transmission.
Also, if you are slipping then you typically will smell it in the fluid when you do a drain/fill. It's not typically the "black super cooked" fluid like when a transmission is almost literally dead but you'll get a good whiff of that burned clutch smell even if it's slipping a little bit.
I'm not running 50 maxlife and 50 matic s I did full transmission fluid change using the machine at my shop it drains pan then fills then you start car and add a quart and take out a quart a bunch of times to fully change all the fluid but I'll try the modifier for sure and go back to maticS thanks for the replies guys you are great
Once I add the modifier I'll give an update I'm at work now so I can't and I work at valvoline Instant Oil Change thats why I was able to use the machine to fully change out my oil with maxlife atf that's what we use on pretty much any car calling for atf
Are you even changing gears in those videos? It doesn't look like you're going hard enough to make the car shift. Get it on a road that you can do more than 30 and pin it and shift at 6 and let's see what it does. I can't understand the slow shift you're describing from the videos. Maybe narrate it or something. Like "here's where I shift and see how the revs do xxxx". But if you don't have a shift kit, shifting at 6 is going to be slow and smushy as hell.
Like when I'm on it hard and it hits about 6000rpm and shifts seems super slow maybe nothing is wrong just need shift kit low rpm shifts seems fine just when I'm really on it I'll try to take a video for you guys give me a little ill get that vid the more I read on the forum the more I notice it's just how these tranmissions are sluggish at high rpm like I said before it is my first auto I have owned
