I have a 2003 G35 Sedan that I have been having issues with recently. I went to turn the engine over about a month ago and I noticed when it started that the exhaust sounded different. It wasn't coming out in a continuous cloud but instead sounded like a stutter. It was also revving quite low, I believe around 400-600 RPM. Revved the engine a bit while in park and the service engine light would only come on (blinking) once it reached over 2000 RPM. The car still has power on the highway but the exhaust still sounds different.

I recently changed the spark plugs (which, after removing each one, was obvious that they needed to be changed soon anyway) but this did not fix the issue. I did notice oil on the two back plugs on the passenger side when I changed them.

Not sure where else to start for maintenance. I was going to get a code reader shipped out but figured I'd ask around to see if this was a common issue or not before the code reader actually arrives. Any advice is appreciated. Thank you.

Is your check engine light actually on?

Not at the moment. The first time this issue happened the check engine light was on for quite a while. I think it lasted between 3-4 days/6-8 separate starts of the engine for the light to go off. After not driving the car for over a month and now changing the spark plugs, the light is not staying on. As I mentioned above, the only time it does come on is when it goes over 2000 RPM. I believe this was not only when the vehicle was in park but also when it goes over 2000 RPM on the road. I would have to take it out and drive it again to be sure of that though.

In that case, I'd hook a code reader up and see what's stored in memory

I wouldn't even buy an actual reader. Download an app for your smartphone and buy the appropriate ELM 327 adapter.

Iphone = use a ELM 327 wifi
Android = use ELM 327 Bluetooth

Apple won't let certain Bluetooth devices connect...the ELM being one of them.

I had the same issue, when did this start exactly? My fix was coil 4 and coil 6 was in the wrong places, then I swapped them around and ran like a brand new G 😝🤗

My dad already bought a code reader while they were on sale, so I guess I'll hook that up the next time he's off work. Thanks, Mustang5L5.

I have just encountered this problem fairly recently. The car ran perfectly until a couple months ago when I went to drive it to work and the sputtering started happening. Am I right to assume that this wouldn't be a coil pack in the wrong spot then because the car has been running fine until now? Is there enough room to switch the coils? I thought they were designed to only reach far enough to their correct spark plug so that you can't match them to the wrong plug if you had to remove them.

Oh in that case, one of your coils are fried, go to autozone, see what codes you get and I'll be glad to tell you what's your problem. I had my G for long *** time and ran through the craziest and rare situations lol if you want to know how to check your coils, start the car and start removing one coil at a time, If the idle doesn't react, then that coil is bad.. But make sure when you remove a coil, put it back on correctly, then move on to the next coil.

So I was finally able to connect a code reader to my car and it gave me the P0303 DTC, which is a cylinder 3 misfire. Do I need to change the coil pack then?