My 04 G has almost 173,000 miles on it. I bought it used 3 years ago with 140,000 miles. I have no idea if the spark plugs had ever been changed, and since I was going to change my oil today, I decided to change my plugs too.

I bought Bosch double platinum plugs at Autozone because they were recommended by the counter man. He said the double platinum were original equipment and if the plugs didn't match original they would burn out the coil. It made sense to me at the time.

While changing the plugs, I noticed a lot of oil on plugs 1, 3 and 5. Like, a lot... I have never had a problem with engine idle, burning oil, or stalling... The VQ35DE has been a great engine for me.

So after I got everything back together, the car idles rough. The service engine soon light came on. And there is a funky, sulfur smell (and a little light smoke at first, which has never happened before).

I'm thinking maybe I didn't get a coil on right or a boot seated properly ...or maybe a vacuum line came loose...

Its my daily driver and a bit of a beater but it has been a good car. It has always run well. Can you help?

 

Sounds like you may have gotten one of the coil wires crossed. As for the oil on the plugs the tube seals are more than likely leaking on the valve covers. Only way to fix that is search on here and find the replacement ones they sell. Or by new valve covers, which are about 250 a piece.

 

+, but I would stick with ngk plugs...they are oem not bosch.

 

Take those plugs you bought and throw them away and use NGK plugs only.

 

This^
Obviosuly that guy is confused, nissan/infiniti only puts ngk in their cars

 

Thanks, all. I checked the coils and wires. Cylinder 4 had a loose coil connection so I tightened it up. Still idling rough and the SES light is still on (steady most of the time, but it blinks briefly at times).

I had Autozone run the codes, which indicated a misfire on cylinder 4. Pulled the coil and inspected. Can't see any problems but then agsin, what would show? Thought maybe #4 and #6 coils might have gotten switched. Changed them around. Still rough.

As for NGK plugs, I know they are OEM. Maybe should have gone with them. But would not using them cause this? I wouldn't expect it to.

Also changed air filter just because it was dirty.

 

Could a bad O2 sensor cause a rough idle? Or a dirty MAFS? But it seems the diagnostic would have picked those up...

 

Okay, logic suggested that if I have a misfire on 4, and my wires aren't crossed, I may have a bad boot or coil. I put in a new coil and boot and still have the problem. Any suggestions?

 

I had switched the leads on #4 and #6 plug coils before changing coil on #4, thinking that may have been the problem. After switching them back, my old G runs fine. Also, looking for valve covers on Amazon, I saw some sets that appear to include tube seals. I know they are factory seated on OEM, but I'm going to look into that.

 

Did you remove the oil from the plug wells before removing the spark plugs? Various problems can arise if enough oil goes into the cylinders.

 

I hadn't even noticed there was oil in the plug wells until I started to pull the plugs. And it didn't occur to me the oil might get down in the cylinder. I did very carefully try to soak up what I could after I got the plugs out, and it's been over a week. No oil smoke in the exhaust, and the car has not run better since I've had it. Hoping it is okay...

Thanks for the tip!