I have an 04 g35 sedan 6mt. I've recently changed the valve covers, plugs & coils. I've changed my plugs a couple times and am pretty sure I reassemble everything correctly. I also replaced my MAF sensor. If I floor it in 1st, I can't even get pass 4000 rpm without it jerking like crazy. 2nd is a lot better. I can get through the revs but you can clearly feel the hesitation every sec or so as you get through them. Once I hit 3rd it's smooth sailing. I did get a p0300 code at once but haven't seen it since. The only code it throws is p1283 which has to do with an o2 sensor. Any help would be greatly appreciated.

 

Possible clogged Cats?

Telcoman

 

Easy to check the catalytic converter, unbolt it (use pb blaster) and look inside, does it look like an even smooth grid or does it look like it has melted "drippy" spots. Melted is bad.

The error code P1283 is lean fuel on bank 2 sensor 1 (drivers side on the header, upstream from the cat) it's possible you have a bad O2 sensor however you also shot a P0300 code which is MULTIPLE cylinder misfire, this makes me think you have a bad coil pack. How did they look when you did the spark plugs? Any bubbled or burned looking spots on them? They usually start to discolor/bubble/burn when they're on their way out. You did install the harness correctly yes and didn't accidently swap cylinders around right?

Checking the coil packs is a bit of a bitch since the cables are tied pretty tightly, pull your fuel pump fuse, crank the engine a few times to remove any residual fuel, remove the coil pack and spark plug from each cylinder one at a time, plug the spark plug in, hold the plug near the block or something that is a a good chassis ground WHILE WEARING A LEATHER OR INSULATED GLOVE!!! (Cause getting shocked sucks), have a buddy crank the motor, you should see spark, if you don't then try a NEW plug, if you still don't then flag that coil pack and try a DIFFERENT coil pack on the same wire (to ensure the wiring isn't the problem).

What spark plugs did you install last time, you said you've changed plugs a couple times? Factory plugs are good for 100k miles. When you changed the MAF did you do the ECU re-learn process with the pedal-dance?

 

Yea a couple of the packs were discolored. I already changed them though. The problem was an intake leak. Got the part from the junkyard an it run great now. Still have the p1283 code. My o2 sensors were replaced not too long ago but I'm about to invest in some hfc's and will probably get non foulers as well. I'm hoping for the best.

 

Awesome glad you got everything running, that code might take up to a week to clear on it's own, or you can wipe it with an OBD2 scanner. If it pops up again then you still have an issue to fix.

 

Intake leak will cause a lean condition.