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

Yeah, I can't imagine a failed throttle body not tripping a check engine light. Did the dealer give you any reasoning behind their diagnosis? I can't remember... does the 04 coupe have one throttle body, or two? I know the sedan went to a dual setup in '07, but I'm not sure on the coupe. Has anyone had the throttle body off of the car? Manually opening it has been known to cause problems. There is a relearn procedure in the FSM (available at www.infinitiservicemanual.com ) but in my experience you'd be throwing codes. Still might be worth a try.

Q451990 wrote: ↑

Thu Sep 28, 2017 8:27 am

Yeah, I can't imagine a failed <a rel="nofollow" href="http://rover.ebay.com/rover/13/0/19/Dea ... KU=3635581" target="_blank" title="Link added by VigLink" class="vglnk"><span>throttle </span><span>body</span></a> not tripping a check engine light. Did the dealer give you any reasoning behind their diagnosis? I can't remember... does the 04 coupe have one <a rel="nofollow" href="http://rover.ebay.com/rover/13/0/19/Dea ... KU=3635581" target="_blank" title="Link added by VigLink" class="vglnk"><span>throttle </span><span>body</span></a>, or two? I know the sedan went to a dual setup in '07, but I'm not sure on the coupe. Has anyone had the <a rel="nofollow" href="http://rover.ebay.com/rover/13/0/19/Dea ... KU=3635581" target="_blank" title="Link added by VigLink" class="vglnk"><span>throttle </span><span>body</span></a> off of the car? Manually opening it has been known to cause problems. There is a relearn procedure in the FSM (available at <a rel="nofollow" href="http://www.infinitiservicemanual.com" class="vglnk"><span>www</span><span>.</span><span>infinitiservicemanual</span><span>.</span><span>com</span></a> ) but in my experience you'd be throwing codes. Still might be worth a try.

I think he is saying that nissan told him is the valve body? Not the throttle body. Two very different problems. If it is the valve body, they mean that in one side of your engine, the valves are not opening and closing correctly, making you lose power. I think a problem like this will give you an engine indication of some sort. With 140K your valve body should have no problems at all, unless one of the cam chain tensioners is lose and your valves are not synchronized. A few coils on one side dead at the same time could be doing the same. I had to change 2 coils on one side on my 2003 pathfinder which is basically the same engine and was showing those same signs of no power. If it is really your valve body, you should stop running the car right now and check your chain and tensioner, otherwise you risk catastrophic engine damage with bent valves or worse. If it is the throttle body a simple cleaning being careful, with the TB out of the car, and an idle relearn should fix the problem. Please let us know if you are talking about your mechanical valves or your throttle body.

There is only one TB on a 2004 so a bad TB would cause everything to be screwed up. Since it's one side that moves it to fuel, air (doubtful), spark, head (valves/cams and function, etc.). Check fuel injectors first, then look at spark plugs as they may be able to tell you which cylinders are having issues. If it's not injectors or spark then it may be time to validate the cams and look further into the head itself.

The whole "randomly" means you should validate all sensors as well