Starting to get some spark knock '05 G35 with 65K

[Q451990]

The wife's G is starting to get a little bit of spark knock. Oddly enough I'm starting to notice this now as it's getting cooler outside - but I don't drive the car every day so maybe I didn't notice it before. It has 65K on the odometer and has never had any engine work or cleaning done. I have just changed the oil and filters religiously...

Any suggestions on where to start? Is this a common issue? I'm thinking of going ahead and replacing the spark plugs since I have them sitting in a box in the garage...

Heath

[SVTCOBRA]

Heath, do you use reg or prem??
Yes, I would change the plugs to see if it helps. Pretty ez and cheap to do.
I did mine around 50K.

[telcoman]

The wife's G is starting to get a little bit of spark knock. Oddly enough I'm starting to notice this now as it's getting cooler outside - but I don't drive the car every day so maybe I didn't notice it before. It has 65K on the odometer and has never had any engine work or cleaning done. I have just changed the oil and filters religiously...

Any suggestions on where to start? Is this a common issue? I'm thinking of going ahead and replacing the spark plugs since I have them sitting in a box in the garage...

Heath

I doubt it is the plugs
I changed mine at 106682 miles and had no spark knock.



Might be worth having the dealer find the root cause before you just start changing parts.
BTW I use regulat 87 octane and have never heard spark knock in my G35.

Telcoman

[RED_DET]

Not every car will experience spark knock because not all cars have the same tune. Certain vehicles may have a bit more aggressive timing set from the factory. If you aren't running premium fuel, then that is the first recommendation. NGK also makes a plug that is one step colder that would solve the issue definitely.

[Q451990]

She's never seen anything under 93 Octane unless it was the first "courtsey fill up" at the dealership... which was actually about 3/4 of a tank. I'm pretty sure the wife has been buying all of her gas at the same station lately, so maybe I'll ask her to switch it up. It will happen anyway since we're going to need to fill up before driving home from the in-laws on Monday. Maybe it's something as simple as that.

I want to change the plugs while it's under the extended warranty more to look for cracked valve covers or damaged coil packs... or if I damage one it gets replaced free. My plan was to do this about 5000 mile before the warranty expires, but I may step that up for good measure. I have noticed that the idle isn't quite as smooth as I remember back when it was new - certainly not rough, but not as good as I remember. Maybe I'll use my pressurized injector flush kit and blast the injectors too... I realize all of this is kind of a "can't hurt anything but probably won't fix it either" effort on my part.

Do the intakes get all carboned up on this engine like my Q? I seem to remember seeing some pretty nasty looking M engine pics, but I can't remember which engine we were talking about. Is it worth buying some gaskets and pulling the upper intake apart to clean it all up at this mileage?

Heath

[SteveTheTech]

Hey Heath,

Before putting a set of plugs in take it for a ride in second gear step into it a little and use manual mode. I would say maybe 20 minutes of so good ole spirited driving, not speeding but heavy throttle application and higher than normal rev range. I'm betting your wife doesn't drive her G hard enough to burn off the crap that can collect in the intake tract and on the tips of the injectors. Think of it like using a cleaning log in a fireplace.

I would suspect you are running a little lean.

Maybe a set of plus wouldn't hurt if that does not work.

Plus you might want to track you fuel econ over the next few months. (easy to do if you have nav, reset the fuel econ averages)

[SteveTheTech]

Do the intakes get all carboned up on this engine like my Q? I seem to remember seeing some pretty nasty looking M engine pics, but I can't remember which engine we were talking about. Is it worth buying some gaskets and pulling the upper intake apart to clean it all up at this mileage?

The gaskets can be reused if care is taken when R&I is performed. Pictures tend to look much worse than in reality. Even some sludge is normal. Carbon from the oil in air filters (which is needed), oil from the pcv system and hydrocarbons from EVAP system are all present in the intake while it is running under certain conditions. The amount and location of sludge can tell allot of the care taken on a G, or qx4 for that matter they are pretty similar.

The plugs in the G are pretty easy you need a few extensions, a flex adapter, 10mm, an 8mm (for the intake). I would also suggest something like this.

http://community.craftsman.com/Craftsma ... ab=details

[Q451990]

I would say maybe 20 minutes of so good ole spirited driving, not speeding but heavy throttle application and higher than normal rev range.

No problem