Originally Posted by dsheldon924

Its rough, carbon fouled after driving for about a week installed new everytime.. Changed em almost 6 times now over the past 2 years

Whats goin on with your 3cyl? Are the plugs discolored ?

Originally Posted by EPiK

check the harness, specifically the grounds. Nissan are notorious for weak grounds. Better yet, get a grounding kit and install too.

Very odd that the car performs on the dyno stationary, but when all 4 wheels are rolling it acts up. Was the dyno a dynojet? Wonder if the same would happen on a rolling road dyno (Mustang)

is there any sensors in the front hubs? maybe ABS/Speed sensor acting up?

Originally Posted by Jimster480

Nah it was just acting up. I haven't pulled the plug recently but it doesnt burn oil or anything.

Originally Posted by dsheldon924

https://youtu.be/A0gKQOgWxv0 -2nd gear pull while tapping gas pedal from 4krpm allowing the gas pedal to fully release in 100 rpm increments

https://youtu.be/RGs_TYX5XXA -3rd gear pull while tapping gas pedal from 4krpm allowing the gas pedal to fully release in 100 rpm increments

https://youtu.be/_ApDK7nhBbM -4th gear pull while tapping gas pedal from 4krpm allowing the gas pedal to fully release in 100 rpm increments

Cipher logs to follow.... please let me know what parameters other than RPM you would like to see....

Thanks,

Dave

Originally Posted by dsheldon924

Bought car for 9k in 2013 @60k mi
Car had minor defect to paint, and interior was like new
Car had small hole in exhaust near muffler that made the car more responsive, deeper growl, and more fuel efficient....until the hole widened, then the performance went away, and my story of modification started...

Mods:
Stillen Cold Air Intake, Z-Tube, K&N Cone Filter
370z Injectors
ACT Stage 1 Racing Clutch
ACT Lightweight Billet Aluminum Flywheel
Stillen Headers
Stillen High Flow Cats
Stillen True Dual Exhaust Gen 1
Walbro 255LPH Fuel Pump

Hi everyone, I have been chasing the original responsiveness the G had when I first bought it to no avail.

I have added many modifications(the ones you see above), and replaced almost every sensor/electronic/component under the hood:
Knock Sensor
Knock Sensor Harness
Cam sensors
Crank Position sensor
Maf Sensor
Rear 02 Sensors
Front 02 Sensors (1 twice on drivers side)
Spark Plugs -OEM
Coil Packs -OEM
Coil Pack Sub Harness(connects to coils 1 and 3)
Injectors -2008 370Z
Battery(cleaned Ground)
Clutch Slave Cylinder
Differential Oil
Transmission Oil
Front/Rear Wheel Speed Sensors
Throttle Position Sensor
VTC Solenoid Valves
Evap Canister Purge Solenoid Valve
Fuel Pressure Regulator Passenger Side
Fuel Pump/Filter
Oil Pressure Sensor

Sadly, after replacing all of these parts, the only thing I have left I can replace would be the Accelerator Pedal Position Sensor, and the ECU that I know of...

I should mention that the car has been flashed with Osiris and dynoed at 280rwhp, however, the car does not feel like it has anywhere near that amount of HP at the wheels. The car is very sluggish on takeoff(feels like it is going to stall), and has no power up until 4800 RPM

I laid out every part that I've replaced on this vehicle the other day and thought to myself how does each part impact the issue I'm experiencing here. The ones that stood out the most were as follows:

-O2 sensors(upstream)
-Coolant temp sensor
-Maf sensor
-VTC solenoids
-Fuel injectors/regulators(dampers)/pump.

The only part I haven't replaced yet on this list is the fuel pressure regulator(damper) on the driver side connected to the fuel rail. I've heard it's very rare for this to fail. Also, the last remaining sensor on the car to replace is the Accelerator Pedal Position Sensor.

Guys, thanks for guiding me with this issue btw. If you ever need any help with your computers, audio equipment, modeling, or acting, please feel free to reach out...as those are my real bread and butter skills...

Back to the issue... Fuel pump replaced yesterday, sounds a little louder than the old, and shows no difference in performance(tired of writing that statement).
*However, I just found out something very interesting regarding the fuel level/responsiveness*:

-When the gas tank is under half full, the car struggles much more in the low end, wants to stall out, gas pedal is not hard to press.
-When the gas tank is full, car is more responsive in the low end, doesn't want to stall as much, gas pedal stiffens slightly.

Picture this, just so we are all on the same page.... I start the car, car idles fine, I start driving the car in 1st gear(wants to stall), shift to 2nd gear, while driving I refrain from pushing the gas pedal hard @ low rpm due to the fact that the exhaust gets really loud, and the car wont move/respond at all(bogged), once in 3rd gear, I steady the RPMS at around 4K(to have some power and not too much loudness), If I TAP the gas pedal lightly/consistently, and let the gas pedal come all the way back up from 4k to 4100, 4200, 4300, 4400, 4500, 4600, 4700, AND THEN OUT OF NOWHERE 4800RPM causes the car TO COME TO LIFE, and I can keep TAPPING THE GAS PEDAL up to redline with extreme responsiveness, and a perfect sounding exhaust.

I will be posting a few cipher logs soon to show this "tapping of the gas pedal" bizarre event I'm experiencing. oh and a video...

So right now I'm leaning towards Fuel Pressure Regulator(driver's side, attached to fuel rail), and Accelerator Pedal Position Sensor.

What do you think? Sell the car already, or keep stabbing at it?

Originally Posted by Raybamm

I would also consider a plenum spacer. Your manifold could be creating a choke point considering everything in opened up before and after it. Just a thought.

Originally Posted by twitch

I watched the first video of 2nd gear pull. To me that looks like your clutch is slipping which would also explain the smell. Just a thought.

Originally Posted by Larimer

More variables at this point is a bad idea. Fix the problem first before doing anything else, there's more than enough air I'm sure.

I'll look at the logs tomorrow and let you know what I find.

Originally Posted by Blue Dream

I'm liking this thread a lot, we don't get this that often. A technical back and forth that brings out the OG's who don't post much to help solve a mystery. Man I miss the old days here, thanks guys.

Originally Posted by dsheldon924

The clutch is definitely being burnt up on a few of these hard runs, but I was associating that with the engine not performing optimally(push gas pedal, nothing lines up air,fuel, spark wise.. Clutch has no choice but to melt somewhere right?) i had this clutch put in about a year ago with livhtweight flywheel,throwout bearing. Let me know if this is a possibility here

Originally Posted by twitch

If your clutch is good and you're not riding the clutch it should be engaged with no smell or slipping. During that run was your foot all the way off the clutch pedal?

The first signs of a clutch having problems is usually slippage. Meaning when your clutch is fully engaged (foot completely off the clutch pedal) and you give it gas the RPM's will rise quickly but the car hardly moves. That noise and jerking that happened was the clutch finally catching.

I remember reading that your dyno wasn't a typical one where the tires rolled on rollers. If that's the case it would also make sense to me that this is why your dyno turned up without issue. If you didn't have any resistance on the clutch because the drive wheels were not on the ground to provide resistance back to the clutch you might not get the slippage. This means everything would seem fine, which it did.

Scott