seth02

Hey Ya'll I've had my 2006 350z for just over a year now, I've developed an issue when accelerating the car wont go over 65 mph or 3k rpms in 4th gear. the car is an auto transmission, I've replaced the maf did the spark plugs and coils last august, the only check engine light code i have is for the upstream bank one o2 sensor that i have replaced but its still showing up on my dash. I've read through some other forums but i cannot find the issue, some people on YouTube are saying its the throttle body and some are saying its the throttle position sensor on the pedal, the pedal feels quite heavy when in higher rpm, when I'm around the 65 mph mark at 3k rpm i have to mash the pedal to accelerate up a couple mph more, not to mention on hills it feels like I'm getting nowhere, I'm tired of getting passed by all the minivans someone please help!

icer5160

iTrader: (4)

Check your throttle pedal for the rubber bump stop.

Do the same for your brake pedal.

When you replaced the MAF, Coils, and Plugs, did you use OEM? (Specifically for the MAF).

You can try the throttle position relearn procedure and also idle air volume relearn. This is typically only required when replacing the throttle body or doing a deep cleaning on it, but may also be required when cleaning or replacing the MAF. Why did you replace the MAF originally? Were you experiencing problems then?
Cheers!
-Icer

seth02

Idk how to work the thread the right way lol

but I did do a relearn replaced the 02 sensor that was “bad” cleared codes and today it came back on, I do have a significant exhaust leak on the right side where the header meets the test pipe, but other than that I’ve done the relearn and maf is oem hitachi, I’m starting to worry it’s something worse than I’m anticipating

icer5160

iTrader: (4)

Which code/DTC is specifically being thrown?

The right side of the engine (passenger side) is Bank 1, it's very likely that your exhaust leak is a contributing factor here. The upstream O2 sensors are relied on by the ECM to calculate fuel/air ratios, timing, and injector duty cycles. If the O2 sensor is faulty or not giving accurate data to the ECM, this can heavily impact performance. If you have access to a scan tool that can show live data PIDs, then I would do a live data capture on both Bank 1 and Bank 2 upstream O2 sensors. The values should be nearly identical, if they are not, then you either have a bad sensor or a fault elsewhere (such as the exhaust leak).

The most common sensor failure on these engines are the CAM position sensors, followed by the crank position sensor.

Are you running OEM exhaust headers or aftermarket? What type/brand test pipe are you running? Did you re-use the OEM gasket? Did you have the engine "tuned" after installing the test pipes?
Cheers!
-Icer

seth02

This is the only code, if bank one is passenger side I have them mixed up. I do have an exhaust leak on the passenger side at the test pipe, I’m running kinetix test pipes, ISR y pipe and some eBay single exit I got. I haven’t got tuned yet running z1 cold air intake and plenum spacer, I need the tune but I don’t have anyone near that’s less than a $1,000 thinking about the z1 plug in but I’m not sure. The car has been amazing up until recent, I’ll throw it on the lift soon and get the gasket not sure what else I can do, the car just feels sluggish after owning it, I’ve been told I’m looking too much into it but I’m not sure.

icer5160

iTrader: (4)

Yeah, that's a lot of intake and exhaust modifications to do all at once, but generally speaking those won't cause an upstream O2 sensor issue (downstream is a different story). Get the exhaust leak sorted 1st. I highly recommend keeping & re-using the OEM gaskets for the connection between the test pipes and exhaust manifolds. The OEM gaskets are very high quality and do not leak (unless seriously damaged). Most aftermarket gaskets included with things like test pipes and manifolds are garbage.

Also, be careful when installing O2 sensors. Do not drop them, do not contaminate them with grease/oils, and be very careful with the wiring when threading them into or removing from the manifold. The wires themselves are very thin/fragile and can break if overly twisted.
Good Luck!
-Icer

seth02

I’ll go get new gaskets when I get paid Wednesday, really hoping this fixes the sluggish and slow feeling of my car. If not I’ll probably move onto the throttle and throttle body, then continue after that.

MelissaPeterss

When you replaced the MAF, Coils, and Plugs, did you use OEM? (Specifically for the MAF).

MelissaPeterss