Hello Seymore4,

I have a 2008 G35S 6MT Sedan with 52,000 miles on it. I have had car since new. Last summer I installed 2.25" Fast Intentions cat back exhaust with 18" resonators. Ever since I have wondered if tuning would help optimize engine performance to better match new exhaust. Or should I just leave it alone? Car is otherwise stock and well maintained.

Reason I installed exhaust was I wanted a bit more engine noise so I could tell when to shift MT better, and hear what is going on with engine rpm when I let clutch out from a stop. With windows closed G35 sedan is so quiet, unless i am on the gas, I can't really hear the engine and know how to modulate clutch and when to shift. It definitely got louder. Probably because every component of exhaust I can see straight through! It does sound terrific though. Not sure what the neighbors think. Honestly, everyone that hears it (and that is in to cars) says it sounds fantastic. I agree, especially if I hold gears a bit longer and shift at higher rpm's. Not great for fuel economy but man, it puts a grin on my face . It is a bit too loud for my tastes though but it's installed and I'm not taking it off.

Let me know if tune would make noticeable improvement. Right now it sort of feels flat at low rpms and then runs good at higher revs. With such an open exhaust and reduced back pressure, I probably traded off some low end torque. Exhaust Pipe diameter is 2.25", not optional 2.5" diameter. I went smaller to try to keep low end and mid-range performance. This is my daily driver.

The other, probably largest contributing factor to making smooth shifting difficult, is super bad clutch pedal feel. For that I have RJM Performance adjustable fulcrum point clutch pedal I need to install this spring. This should make it a lot easier to shift and more relaxing to drive. I have tried all the other clutch pedal mods on this and other forums, with some improvement but none really address the root of the problem which is disengage to engage points in clutch pedal travel, are too close together, making it hard to modulate. I have been driving manuals my whole life and not until this car have I ever stalled so much. Over the years, I have learned to manage it but it is annoying.

Thanks.

 

A tune makes a difference on every G35, even stock ones.

 

OK. What equipment do I need? From reading, I believe I need an UprRev or Osiris(?) license, Install software on laptop. and a cable to connect laptop to car's OBD2 port. Once this is set up, record ECM data while driving. Then send data to tuner for analysis and adjustment?

Roughly how much am I looking at for equipment, software license and tune?
When recording ECM files, what should ambient conditions be ideally?
How does tune impact daily driving fuel economy?

I also see that one can switch maps using cruise control buttons. So one can switch from performance tune to stock tune to fuel economy tune to rev limiting launch mode. That's pretty slick.

Thanks

 

All you need is a windows laptop, the kit comes with a OBD2-USB cable you use to flash the ECU and datalog. In a nutshell the process is: Flash the base tune, record datalogs, flash updated tune, repeat until you're done. Cost is $550 for the basic kit, add $100 if you want the ARC upgrade (launch control, rolling anti lag, burnout mod). You should see a slight increase in fuel economy with a tune. Feel free to PM me if you have any other questions,

 

Seymore4,
OK. I'll follow up with you on PM. Thank you.

 

Question: 5AT with plenum spacer, Z-tube, grounding kit and tune. If a Transgo kit is installed, is a retune warranted?

 

Nope

 

Thanks!

 

I got a question. I have a 2003 G35 coupe, car was tuned by SOHO back in September 2018 with no problems whatsoever. Now it's giving me the infamous error below. Was told from uprev the OBD2 needed to be repinned. After inspecting the OBD2, it looks like it was already repinned. So it's has pin 3 moved to slot 14 and its still giving me the error. I also don't think the car is running it's original ECM. I would hope the bench tuning isn't my only option, SOHO seems to think they were able to successfully tune it from the obd2 port but they can't confirm since they said they didn't document much and the original owner doesn't remember. So right now i'm locked out of the ECU. I can datalog and clear DTCs but it doesn't seem to be letting me flash. Any thoughts?

 

Are you a protuner? Call Omar

 

I am not... My tuner took the snapshot. I'm trying to diagnose the issue on my own to save money on shop hours from my tuner. I have just the uprev cable and the tuning software for just flashing roms onto the ecu... I have the ability to duplicate the problem by trying to flash a rom onto the ecu... so right now i'm trying to troubleshoot until i am able to flash the car with my standard tuning abilities on my own before i take it back to my tuner.

I've been speaking with James at uprev, but he says i need to bench flash the ecm... which doesn't sound like a actual solution.

Car runs fine... i just can't plan for any future upgrades until i can get past this issue. I don't want bench tuning to be my only option... not a lot of tuners like doing that and it's not very cost efficient.

 

As long as it was repinned correctly you should be able to flash it.. I've had that happen a couple times but it was always random and resolved by simply resetting the ECU and trying again. If you can duplicate the problem with a different cable you know its not a cable issue. I would try bench flashing it once to rule out defective ECU before you look into wiring

 

Sounds like a plan! I'll try that first. Thanks for the input!

 

Am I correct in saying that Uprev is the only company that can tune Infinitis? How have they been the only ones to provide such a software for this ecu? I believe they literally have a monopoly over tuning this platform.

 

You are not correct. EcuTek is another popular option.