Hi there, I have a 2008 G37S 6MT with 230kms on it. Car ran smooth until recently when I did a muffler delete. My car feels like the power gets cut off and slowly accelerates until after 3000rpms, then the thing takes off like a rocket. I do all the maintenance and use liqui molly 5w30 oil. I have gotten my MAF Sensors cleaned, throttle bodies cleaned and re learned by the dealership and still nothing. I see a difference after the 3000rpms, car feels more responsive after the clean but it did not fix this issue. The tech mentioned that it can be one of my cats that is plugged. I have searched and searched and did not find anything. Any help would be greatly appreciated.

Also when I take it out of gear, rpms drop as usual til right before 1k rpms, it lags for a millisecond and then it continues to drop to normal idle. I live in Ontario Canada, and sometimes the thing is very responsive from low rpm, but past two days, she has been struggling under 3000rpms, I changed the spark plugs with OEM ones about 3 months ago.

I think it could be the throttle bodies, I might just change them both, I found used ones that came out of a 2008 automatic, hoping they should fit on mine no problem, but im still trying to figure out what this issue can be.

Any help is GREATLY appreciated.

 

are you throwing any codes? those symptoms usually result in codes, especially if there is a cat problem, the car could be detecting an overly lean/rich condition and compensating...

 

no engine light is on, and I have not plugged in a computer. I will go to part source and plug in the computer to see if there are any pending codes.

I keep looking and looking online, and a few people have complained about this issue but have not found a fix to this.

I might buy a set of throttle bodies and replace them both as they have the throttle positioner sensor built in them.

I will see if this will fix my issue, but in the mean time, nobody has any fixes towards this problem

 

hey guys, so I've been looking into this problem quite a bit. You can also go on the 370z forums to find more info on this. Anyways after cleaning the throttle bodies, changed spark plugs, cleaned mafs and pretty much everything else, somebody mentioned that it can be a faulty crankshaft positioned sensor. Somebody else mentioned a camshaft position sensor. Pretty much if any of these two fail, you feel a loss of power at low rpm and all sorts of other problems. Something to do with the variable valve timing or something which made it go retarded. You should look into how this part works, pretty cool imo. I got the CRANKSHAFT position sensor not the CAMSHAFT position sensor aftermarket from partsource ($120 bucks) and installed it myself. Make sure the exhaust is cold and it's kinda tricky to get in there. You need a 10m with a short extension and a flexible socket. There is a heat shield with a 10m which you can just loosen up and push down, and then there is another 10m to actually take out the CRANKSHAFT positioned sensor. Took it out, cleaned the edges (make sure no debris gets inside) and replaced it. The difference was night and day. Make sure to break it in nicely, so drive with respect, as these ladies deserve it. I hope this fixes my issue which was acting up under 3k rpms and what not. It felt like a 100hp 4 cylinder was running up until 3k rpms when a glorious trumpet would arise and sing its melody of the beautiful VQ engines. I really hope this helps. Btw it did use to throw some codes but I kept deleting them. Eventually the car was acting up. Something about a bank 1 or 2 cant remember.


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my suggestion, before you start tearing your car apart, is to put the muffler back on the car and reset the ecu to see if that is causing your problem. these cars can be pretty finicky when it comes to exhaust mods, at least my car is. might save you a ton of time and money. especially since you didn't have this problem until you removed your muffler.

 

"Btw it did use to throw some codes but I kept deleting them."


Didn't we ask earlier it it was throwing codes? And you didn't tell us what they were?

At any rate, Congrats on finding the source if your issue.

 

did this fix your issue im currently having the same issue