long story short: i have a 2007 base model 350Z with osiris and cruise control. it worked perfectly fine before but i recently put in a LSD i think it was out of an automatic with a higher ratio, 3.5? which i actually wanted? but im not sure, in 6th at 60 im at like 1900 and it makes 6 almost useless.

gps to speedo error was off like 3mph at 60 (60 speedo, 57 gps)

anyways since i swapped to LSD my cruise control wont work in 6th but perfect in any other gear. i heard someone else that had the problem but im having a problem finding the post again.

any ideas please let me know.

 

Base with cruise control? What year? - which might have been helpful to begin with, just saying......

 

edited first post* its a 2007 350z, and yes its a base model with cruise control i run the ev12a ecu

 

Just some ideas about your problem. I don't claim to be an expert.

I suspect the CC system compares the speed of the engine to the speed of the front and rear wheels when the car is in sixth gear, and the different ratio on the LSD is making it appear that something is amiss. The system wouldn't be making that comparison in the lower gears, since the engine speed is obviously going to be higher in relation to the wheel speeds.

You might read through the explanation of how the ASCD (CC) works in the service manual to verify this.

Does the car have traction control? Have you tried turning it off to see if the CC will work?

It sounds like your car isn't a standard OEM configuration, even before the differential swap. If that's the case, you can't expect things to work like they normally would.


I also suspect this another interesting thread that will die with no answer because it got moved to a sub-forum before many people got a chance to see it.

 

Winchman - I can see "moved" threads with the notation "Moved" in them so i don't see the problem? Here is where my bookmark takes me:
https://my350z.com/forum/2003-2009-nissan-350z-2/ and it seems to include all Moved threads.

 

Well the speedo goes off your rear wheel speed sensor, gear ratio has nothing to do with speedo. If your speedo is off , it is because of tire height. But as mentioned, the ECU could flip out because of the RPM to vehicle speed for cruise control.

 

Base models did not come with cruise control, so guess I am still confused. Is that an aftermarket ECU or one from a Z other than a base? If so, I imagine there could be a litany of reasons you are having problems.

 

So you have a Base 6 speed with auto LSD, cruise from a non-base car and an ECU from a non-base car? I gotta say, I don't think you will find many people who can relate. Myabe flip through here:
https://my350z.com/forum/showthread.php?p=9603893

 

thanks for the replys, i understand some may be confused about the configuration i have.

thanks for your ideas winchman, you bring up a good point about traction control. no i dont have traction control and i could see that may mess with it.

im honestly not sure if its an auto LSD because the rpms seem about the same at 60 as they did before. its just very confusing because it used to work in all gears, now it works in all except 6th.

that thread is the one where i saw the other person with that problem, looks like im gonna be reading a lot






if anyone has a vq35hr 6 speed, if you could let me know what your rpms are at certain speeds

 

Post your tire size info just for ships and giggles. Front and rear.

 

i have the stock 07 wheels
i believe they are 18x8 18x8.5
tire sizes are F = 225/45/18 R = 245/45/18


new wheels are going on soon 18x11.5 18x12 with 245/45/18 all around

if you don't like stance you guys probably are not gonna like me


im pretty sure it is an auto LSD which is the 3.3
i read the thread about the other person that had this problem and he went from a 3.5 to a 3.3 and it didnt work but i guess higher ratios will but lower ratios wont.

also explains why im so low rpms at casual speeds
what is this doing for performance? i run 100shot and probably put down 350whp is the 3.3 better or worse? not that im gonna spend more money to get a 4.08 installed but i could see about getting the old (3.5?) installed on the oem LSD unit