This is my second coupe with 140k miles on it. Ever since I got it in Feb of this year it was just a whole nother episode of the first. The power you feel in the steering wheel, the sexy drone and purr in the exhaust note, the back 2 tires burn out everytime i touch the gas to go... yall know the life . Well about 3-4 months ago my car randomly lost about HALF of its power and the the exhaust note LITERALLY only comes out of the left exhaust and the right one has gotten mute, wtf? At a cold start i can see smoke evenly coming out of both pipes but sound only coming out of only one now?? I have NO check engine lights on, i took to NISSAN and they say its my valve body?? I think theyre bullshitting me because it wouldnt cause 3 different things to happen to the car with no check engine light right? As of now the car starts up like a toyota and drives as fast as a charger, exhaust note only coming out of the left pipe, and a rough idle... please lead me in the right direction

 

I would start by inspecting the cats(if you have them) all G's have a tendency to burn them up and sometimes fall apart. And if its the rear core behind the O2 sensor it would not through a code and would possibly clog up one muffler. But normally with this problem you would hear rattling. This would cause poor performance as well. Smoking is questionable only at start up, could be a semi clogged injector causing smoking and rough idle which would have killed the cat.

 

You sure they said "valve body" because that's a piece inside an automatic transmission. Yes a valve body failure might not throw a CEL since it's not part of the engine management system, TCM controls are it's own separate monster.

Best way to check for exhaust balancing on the fly is to get some white powder like lifting chalk (if you're a gym rat), all-purpose flour (if you're a baker) or other white powder (if you're Scarface) and lightly sprinkle it in front of the exhaust tip with the engine at idle, it should blow all over the place even at idle pressure. If you have literally NO FLOW WHATSOEVER then you have an exhaust problem, possibly broken diverter baffles inside the muffler, cracked welds somewhere, etc. You can test for sound balance by using your smartphone, download a "sound meter" addon that will measure decibel levels and hold the microphone at the same distance/angle from each tip, they should be relatively the same but within about 5dB of each other.

Next question:
A smoking engine is something that needs to be fixed, I hope you mean it's STEAM coming out of the pipes from cold-start condensation/evaporation.

It's VERY easy to remove the muffler on this vehicle, if you have a lot of corrosion on the fasteners just buy a can of PB Blaster and spray it down good for 2-3 days before removal, take the muffler off and inspect the inside of the pipes, borescope if you have one for your phone, shake it vigorously and listen for anything bouncing around inside.

As for the rough idle, pull all plugs and check them, replace with OEM STOCK PLUGS if they have some random aftermarket ones installed or if they're old, inspect each coil pack for damage like burning/blistering of the spark plug well shaft or ANY damage whatsoever to the epoxy resin encasement on the top. Perform idle air reset, throttle body recalibration, pedal recalibration steps by doing the "pedal dance" method, use a timer and do it right or it won't work.

This is a good start and you'll likely find the culprit.

 

Thanks for the replies my friends. Now to fridaytech21 i always did suspect the cats but i heard they would be glowing if they were clogged? I also did over the past couple months get random trip codes and i cleared them and they never came back. As for the rear core clogging up one pipe how does that work? To cleric670 yes i meant steam coming out the pipes at a cold start, so far what I have done is clean the fuel injectors, throttle body, gave her a tune up, synthetic oil change, seafoam method, and even tried using catacleaner and nothing worked /:. And not to mention Nissan did me a FULL ECU RESET (which finally reset the tire pressure light ) so i literally tried everything to this car except checking cats... and had it inspected at 5 different shops with no answers... can this possibly be a stupid sensor?

 

Oh and yes... they literally said VALVE BODY in the transmission and showed me a picture of one for $3500 no misfires and it shifts smooher than any car ive had, i know my G still has about a decade left in it and im not letting it go

 

@fridaytech21

 

Yeah the valve body is basically the heart of an automatic transmission and they are definitely expensive, $3500 from the dealership is a little outrageous though. The part at dealership prices is $800 FROM NISSAN, that means they want $2700 for a repair that doesn't even involve removal of the transmission ??!! I would ask them for a full itemized price breakdown because something is DEFINITELY wrong, it doesn't take 20 hours of labor for this repair...I suspect they're trying to sell you an entire transmission.

Cats have a number of different ways to fail, I've personally seen them turn a nice glowing cherry red color, then turn into a liquid and drip right out of the casing. The best way I know to determine if it's in the death cycle is to remove it from the vehicle and look in both ends, if you have a problem it will typically have "melted looking spots on the honeycomb-looking grid" inside, typically on the intake side of the pipe. If it doesn't look PERFECTLY symmetrical on every centimeter of filter media then something is probably wrong with it, just google "melted catalytic converter" you will find plenty of examples and a nice clean photo of a brand new on speed.academy.com will be in that google search.

In poor light conditions or if it's dark it's normal to see a very slight glow coming off a catalytic converter if you're really pushing the vehicle hard, it's incredibly subtle though and you will usually never notice it. If you can see it during the day then you have a serious problem.

 

Yeah i doubt anything is wrong with the transmission im sure that part has a bunch of sensors that wouldve atleast triggered some type of light or driveablitlity issue, im having more of a driveability loss if you would say. Definitely gonna go back and have them test the cats, thanks for the info bro

 

Clogged cats would definitely kill engine power.

 

definitely sounds like the cat. i've had them fail and not glow at all in my last vehicle (01' blazer). Drove a good 2 hours to get it home on a mostly clogged cat. couldn't break 60 mph, took forever to get up to speed. got home, cut the cat out myself, drove it like that to make sure that was it (got my power back, yay!) then went and got a piece of pipe put back on.