Hi guys, new to the site. I know there have been previous posts with similar concerns so bear with me if this is redundant and i wasn't looking hard enough for answers....

Anyways, i have a 07 g35 sport sedan AT with about 190k on it and the only mod is a Stillen gen 3 CAI. I have noticed before that the car will hesitate/lose power when accelerating from a stop around 1k-1200 rpm and then run smoothly up the gears like normal but more recently the car will shut off completely and i will have to start the car back up. I have seen people say to clean MAF sensors, throttle body, relearn idle and all that was done by my local mechanic and it would run smooth for a little while after until the engine warmed up a bit and it would start hesitating again. Also read that replacing the camshaft position sensors and the crankshaft sensor could fix this but after it died again yesterday i decided to take it into the dealer this morning and see what they would say. They called and said they couldn't find anything besides that the car was running too lean? so too much air was going into the engine and they said to change back to factory intakes and see if the problem continues? My factory intakes are at my parents house 6 hours away so not necessarily an easy option but can be done or should i dig in the pockets and replace the three sensors first? Any ideas or tips would be greatly appreciated. Thanks!

PS also want to add that i am looking at selling the car soon.

 

Too lean is almost always a vacuum leak. And they will definitely cause a hesitation when you give it throttle, sometimes to the point of killing the engine.

I definitely think you have a vacuum leak.

 

No harm in throwing a scanner on it to see if there's any hidden codes though.

 

dealer said no codes were popping up...just said to put in stock intakes or try and get it tuned at a shop.... might buy the camshaft position sensors to try them out as well...

 

Sure if you just want to throw parts at the car and hope something sticks

What was the LTFT? What diagnostic steps did they take? What was the result of the oscilloscope/Consult-III test for the cam sensors?

Better to actually TROUBLESHOOT the issue, your intake tubes by themselves aren't causing a lean condition, but if there's a tear in one of the boots then THAT could cause the problem. If your PCV hoses are old and don't fit tightly on their fittings anymore THAT can cause the problem, if the PCV valve is stuck open THAT can cause the problem.

LTFT will tell you how much % more fuel the engine is pushing to keep things within the margin, if STFT has a big lean spot on throttle tip-in and LTFT is adding 10%+ more fuel then it's almost definitely a vacuum leak which is VERY common on older vehicles.

You can usually just feel it though, in park at idle stomp the pedal WOT, if it bogs and sputters a little before revving then it's probably a vacuum leak.

What are the condition of the plugs, when was the last time they were replaced or the gap checked, if it's bogging under load or higher rpm stutter then it might just be old plugs, they're really only good for 60k before performance is degrading pretty rapidly.

 

I find it really hard to believe that you brought the car to the dealership for a diagnostic and they found NOTHING. Hell you said the car will STALL OUT if you punch the throttle, I doubt they ran a single diagnostic with the Consult tool. At very least they should have recommended flashing to the latest software version. The stock HR ECM tune is notorious for throttle issues on older software revisions, there's even a TSB about it.