Hey guys. This might be long but I need help. Here's my story.

I have a 2007 G35 Sedan with a lot of miles. 160k miles. I have not had any issues with the car and absolutely 0 check engines/ codes. A bit ago my car started hesitating at take off and during bumper to bumper traffic. It feels like the RPMs would drop and then go up. One day my RPMs dropped enough that my car turned off.

I took it to a mechanic the next day and he saw a Bulletin for 2007-08 G35 sedan needing a ECM/ECU reprogram. He suggested I go to the dealer and get that along with a relearn.

I go to the dealer and they won't do it. According to them and their computer (I still have no check engine or errors), my exhaust timing sprocket and VTC cover failed which caused a misfire and why I'm feeling hesitation.

I end up getting 2,3,4 other opinions from mechanics and none agree with the sprocket issue that the dealer mentioned. According to the other mechanics and when they hook it up to their computer, They see no errors showing up. They all mentioned if my sprocket was bad and causing misfire i would be throwing codes left and right. They also recommend I get the ECM/ECU reprogram. I tried going back to the dealer but they still wouldn't do it.

Have any of you guys had this problem? Any suggestions?

btw on the description of service, the only code they have next to the suggested repair is J0001.

 

Hey I'm going through the same issue with my 6mt G from 2003. Taking a ride with the head tech at dealership tomorrow with consult II connected in hopes of finding the issue.

The tuner that I use in Connecticut suggested that my VTC Solenoid is plugging up intermittently due to wear, and causing the engine timing to retard/advance which doesn't allow the exhaust or intake to breathe/pull air properly.

If this is your issue (and hopefully mine) there is a website that sells like new used OEM for real cheap, and you they are real easy to access/replace. See below

http://www.z1motorsports.com/cylinde...id-p-5732.html

Also a DIY
http://my.prostreetonline.com/2014/0...olenoid-valve/

 

So after "extensive" testing at the Infiniti dealership in Albany NY, the techs came to the consensus that my vehicle is "running a little rich", and the pulley belts are a "little bit worn".

Just so I'm not going crazy here, "running a bit rich" cuts the engine power in half?

Looking up the number to the second closest Infiniti dealer now...in Connecticut.

If the dealer in Connecticut confirms the dealers opinion in Albany, then I will release all the hair from my head with my finger tips, sell the car, and buy a 95 ford tempo so I stop spending time and money on a car that is not responding to anything I do, that "checks out fine" according to multiple certified dealerships.

This should be noted as well: The car has no power in the 0-4k rpm range, but if I allow the engine to coast at 4k rpm and blip the throttle, most of the power/responsiveness comes back, but only until I switch gears, where it goes back into bogged down(running rich) again under 4k rpm. The difference is like driving a new ferrari, then back to a rusted out honda civic that needs a tune up if anyone needed a picture painted. Thinking this is due to the VTC solenoid getting stuck at low rpm, then releasing at 4k rpm due to engine load increase? not sure, and any suggestions helps. Grabbing some cheap OEM used VTC's off of ZI motorsports today to isolate.

https://www.z1motorsports.com/cylind...id-p-5732.html

p.s. I couldn't make this up. The tech and I were doing a test drive together(tech was driving). We stopped at a red light with a Honda minivan next to us. The tech mashed the gas pedal at the green light to about 5k rpm, switched gear, rinse-repeat, until 4th gear. We look over to see the same minivan ahead of us on the left. I said "so, that minivan must have an engine swap or something huh?" he replied, "the minivan got a head start". It was at this moment, I almost pinched myself to remember I'm not in the twilight zone.

 

If you're running rich, you're getting more fuel than air. Is your throttle ok, is it opening correctly, is your intake filter clean, is your maf sensor clean.

 

My new replacement air intake just came in today, so I'm going to try to isolate the issue there..will let you know how that goes...

My maf is clean, throttle had to be replaced recently due to the car trying to kill itself, see my post here http://www.6mt.net/forum/nissan-gtr-...ow-rpms-4.html with video of this frightening event ...but thats clean...

I'm having the oddest issue, where the car bogs terribly between 0k-5k rpms under load(driving forward), but if you let the gas pedal come all the way up while the car is moving forward at 5k+rpm and then hit the pedal again, the car wakes up! and has tons of power again!!!?? but only between that 5k-7k range in any gear I do this....

Here's the kicker... the car sounds like a champion in idle, and runs perfect on the dyno....
I'm currently looking at anything that changes when the vehicle undergoes load...i.e. coolant temp sensor, front wheel speed sensors, (revolution sensor, tcm -not sure if 6mt G has either of these...)

Also, being that I'm running way too rich, I'm looking into fuel pressure regulator/fuel filter/fuel pump as a possible issue here too...the guy that owned the car before me ran 87 in it instead of 91 like he was supposed to...for years....not sure if that could have damaged anything...

 

Isn't their a relearn procedure after replacing the throttle body.

 

Indeed, which I perform every time after I disconnect my negative cable, just because this vehicle depends on the electronics heavily to operate in an optimal state, which disallows mechanical damage from occurring.

 

My G35 decided to reject the second throttle body/TPS (used) today that I replaced a few months back... This time, the low end also seems to be affected...see video below

This problem is getting a bit ridiculous at this point... I've never seen anything like this...especially on a vehicle that is so well maintained....

If anyone has any suggestions, please, let me know... I can't keep defying logic much longer

 

The second demonic possession has been resolved(fingers crossed). Heard hissing from PCV Valve, and replaced with an old one. Seems to back to it's shitty self ...

Also, the new dyno tuner I went to asked me to swap the coolant temp sensor, maf sensor, fuel pump/sock, and relays for fuel pump/ecu/throttle position controller due to the bogging under load issues I'm having(which makes sense as all three can perform fine at idle, but fail/weaken under load without producing a CEL).

So far I've swapped the coolant temp sensor, the maf sensor, and relays for fuel pump/ecu/throttle position controller with no differences shown in performance.

Still a slug off the line, and wakes up if I tap the gas pedal, and let it come back up to rest several times around the 4500 RPM mark

 

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?

 

It's not fuel brother... It's air... You got a air leak somewhere or your MAF sensor... go buy some CRC Mass Air Flow sensor cleaner and clean it, then hit your car with the idle relearn full process (thottle valve, idle air, accelerator pedal)

90% sure you car is lacking air! If you need help, just text me, I'll show you what to do exactly

 

I'm in dire need of help bud, I'll text you shortly. I have 2 maf sensors currently, and I've swapped them with no difference in performance, but I suppose they could both be defective...
I will clean them with that CRC cleaner you suggested in the meantime/perform the three relearns you mentioned , thanks again

 

This is a long shot, but I see you have a 6MT. Could it be that you clutch is contaminated, so when you rev up, it burns off and the plate grabs and runs fine? If I understand correctly the issue is not with RPM response to the throttle pedal, but an issue with the car not moving as expected. I may be all wrong, but it sounds you have tried everything else without any luck.

 

Hopefully he fixed the problem since his last post if from a year ago.

 

Not sure if you still use this account.just wondering if you uh can help me out with my 07 g35x when it warms up it starts to idle high.then idle hunt.if I turn on the ac it wont idle hunt anymorea.when it fully heats up it starts to hiccup/hesitate/around 3rpm cel blinks and would stay off but 10 15 min it throws p0507 idle higher then normal.im 1600 kn the hole and just want to start triking her out. Thanks in advance