algy

The car is a Infiniti G35 non revup 5AT. Got a single turbo kit put on a few months back and put only 4-5k miles on it so far. Car ran great from the get go and recently the car has a rough idle. No light or codes are being thrown. The symptom I have is the rough idle and when I put the car in D or R with a slight brake pressure, you can feel the car bucking (jolting forward or backwards depending on gear selection) as you hear the engine firing like its cammed. The car runs fine though when you get going but at the low revs you can hear it doesn't sound like its all working.

Side note, the car smokes after it builds boost and I get off the gas. I know that probably has to do with the turbo seals on the turbo giving out since I see slight oil stains on the rear of the turbo around the bolts. So that has to get replaced. Also did notice the breather hose that connects to both valve covers is leaking, but I am not certain that it can cause a rough idle.

Checked intake piping to see if it could be oil inside - negative, none.
MAF sensor - have not actually checked or cleaned.
Checked AF sensors with scanner - both sensors read equally.
Coils/Sparks - Already replaced sparks before the build. Coils have not been replaced (113k miles on car)

Any help would be appreciated.

Fluxil

Start with cleaning the MAF, if that doesn't work check your air filter. It's possible it is dirty or has something nasty in it. If that doesn't work then more than likely it could be a coil pack going bad. I recommend getting all new ones. Also check your valve cover gaskets, check your spark plug wells if there is any oil in them then you'll need new valve covers, but I doubt it's that.

algy

Cant be the valve covers. Just replaced them on the car before the build. Luckily, I have another g35 sedan. Ill swap over the coil packs and MAF and see if that will do the trick.

But on another note, you think it could not breathing correctly

Fluxil

That could be it, my buddies 04 Z did the same thing and it come to find out his air filter was blacker than ****.

algy

I'll check that right when I get home. Could be a possibility since it's a cold air intake that sits straight to the opening front duct.

Did it fix fix the problem for your friend?

Fluxil

Yes, we cleaned it and it worked like a charm.