Hey guys a month ago I bought a 220km 350z.

No issues until I went for a weekend trip, car struggled with poor acceleration and rough shaking when idle.

Uncle tested ignition coils, replaced one and she was as smooth as ever.

Fast forward few days later, shaking when idle, poor acceleration and BOOM- rattling coming from my exhaust?

Struggles to kick over between 3000 -3500rpm , poor accelation performance. Haven't drove her since.

Could this be a catalytic convert issue?

im a car noob so pls hit me with hella info

 

Sounds like bad cats

 

The first thing you need to learn is all cars after MY 1995 are equipped with on-board diagnostics, series 2 (OBD-II). This is the “viewing window into the car’s computer”. Plugging into the OBD port under the dash reveals what are called DTCs for diagnostic trouble codes. This is known as “pulling codes.”

The DTCs reveal problems with the various systems and sub-systems that control your car’s operating parts.

That all said, you should take it to a shop that can read the codes or buy an OBD scanner and learn to use it. Helps to narrow down the possible causes of most issues. Properly interpreting the codes takes more study and consulting shop manuals but it gives you a lot more control over repairs that you or a mechanic make.

 

^Very often plugged cats are hard to diagnose as it’s not a monitored part of the vehicle, so usually will be no code. There should definitely be a code for the misfire though.
Check the codes and figure out if it’s a specific cylinder, or if you have a random misfire; a random misfire can indicate a plugged cat, but could have other causes as well. Fix the misfire and go from there, if you’re confident it’s a plugged cat the best way I’ve found to diagnose it is a vacuum test, you will need a vacuum gauge for that and some basic knowledge of engine operation. If not, you can try taking out your upstream 02 sensors and seeing if the power has increased, if it has its pretty likely that your cats are plugged (since pulling the 02 sensor is allowing exhaust flow which would otherwise be restricted by the cats)

 

Sup Ponyryd, beg to differ.
Catalytic converter effectiveness IS monitored by the downstream O2 sensors. When they reach 94% efficiency they throw a code and CEL.
I do like your idea, though!

 

Possible I suppose, but over 20 years in the trade and I’ve never seen an over-efficient catalyst dtc…do you know what code that would throw?

 

Lol.
The only purpose for lower O2 sensors is to recommend catalyst failure.
But you knew that .
Enjoy your evening!

 

so i’ve been having this p0300 code on my 2003 350z for quite some time now, i’ve gone through the works replacing the coils(z1), plugs(ngk), and injectors(bosch). also gone through and bought new gaskets for the plenum even did a valve cover job because it was leaking oil, it was also leaking a bit into the plugs at least i think i never saw a puddle of oil in the tubes but when i pulled my plugs before doing the valve covers i saw some oil on the threads and o ring of the plugs. i also have freeze frame data of my fuel trims being excessively high, i’m at a loss here guys if any one has any ideas it would be greatly appreciated!
i ended up replacing the valve covers and still a misfire but no leaks!
DTC_CNT : 2
FUELSYS1 :CL
FUELSYS2 : CL
LOAD_PCT :18.0%
ECT (•C) : 98
SHRTFT1 : 6.3
LONGFT1 : 9.4
SHRTFT2 : 2.3
LONGFT2 : 9.4
RPM : 650
VSS : 0
SPARKADV : 16
IAT (•C) : 34
MAF (g/s) : 2.75
TP : 1.2
O2B1S1 (V) : .280
SHRTFTB1S1 : 7.0%
O2B1S2 (V) : .190
O2B2S1 (V) : .090
SHRTFTB2S1 : 3.1%
O2B2S2 (V) : .280
thanks for any help! i know you guys are the Z experts

 

It is for sure the cats that causes the rattling. Mine is being replaced right now

 

Hi guys
Didnt know how to start a new thread ( I’m new here) so I figured I’d post under here.
So here’s my situation, my car (2005 DE, Popcharger intake, muffler delete and possible decat and tune) went in to get a new clutch that was apparently stage 2
got the car back was running fine, hour or two later car was misfiring bad and sounded like a muscle car, took it back got the car back the next day ran fine hour later it misfired and was running the same as the previous day. Keep in mind there were no codes at all. And it only ran like this once the car was warm. I then figured maybe the MAF was just dirty hoping that it would be that and not something serious, took it out and cleaned it, car was fine. Two days later I drove the car and once it was warmed up it started misfiring again and again sounded like a muscle car, but then it went away 2 minutes later, however was misfiring abit after. What really made me come here and post is, a day or two ago I raced my buddies e46 330i (keep in mind only mods he has is intake and muffler delete and decat no tune) and I lost every single time, the second last race we were dead even, and the last race he pulled on me hard and I lost, he himself said somethings wrong with the car, and our buddy who was with him aswell, who I previously raced while on oem clutch and pulled on him by 2 cars (keep in mind they both have the same amount of power and raced a day before meaning if I had to run him again I’d lose) a 225bhp car vs a 287bhp car, so please can someone give it to me straight because I’m going crazy here, what could my issue be
I know DEs are slow but come on I should’ve pulled on him easy
please help

 

Possible cam or crank sensors?

 

Update:

I took the car to Nissan they inspected it and came back and told me the car is 100% fine however there is a software issue, they said they were unable to get into the cars software and tried to restore the ecu to factory settings and it would kick them out of the software… So I’m still at square one.
Could this be a bad tune? Maybe the car is running on a fail safe tune and it’s restricting it’s power?
Also I forgot to mention when I bought the car the previous owner said it had some performance chip installed so maybe that chip is causing an interference with the ecu and forcing it to run on a fail safe tune? Please help guys