I'm getting a slight predetonation sound coming from my engine. It's when the engine is not under load and usually cruising (foot off gas) from 20mph to 40mph. It is very light, but I can here a rattling noise.

This started after I removed the front spark plugs, put some anti-seize on the thread and reinstalled them (torqued to 15 ft pds). Are the coil packs designed only for certain cylinders? Could something else be the cause of this noise?

 

Predetonation is a ping or in worse cases an knock,
is that what you are hearing?

 

And also only happens when your engine is under load.

If your hearing noise under a no load condition, it's not ping or spark knock.

 

Sounds just like a ping (not a knock)...very faint though.

 

If it's not under load, then it's probably not pinging. It could very well be the "missing mystery screw" from the power valve, which would suck b/c you'll most likely need a new engine...

 

No, I checked that and the throttle body yesterday. Both screws present. Could this happen if the spark plugs were not torqued down tight enough?

 

I tell ya what I would do, Take each one of those 6 puppies out
and re-check plug gaps, and at the same time
make sure torque is correct, and coils are on good.

 

Could be the precats breaking up...WILLSE had this problem with his precats. Not a very good thing...

 

What is the correct torque? The manual says 14 - 23 ft pds. I applied 15 ft pds.

 

How was he able to diagnose it? You know what Nissan will say. "Normal"

 

15 should be good, but check your gaps.

 

Yes, I also get pinging on light load around 40mph on my bone stock '03 SE. I've had it to the dealer twice. typical response... normal, no problem. I always run Mobil or Sunoco 93. I've had the ECU re-flash and all the known TSBs done. Not sure what else to do.

 

Interesting. Let me ask some questions of you:

1)Any changes to sparkplugs?
2)Which TSB/Recall have been performed?

I'm leaning toward several conclusions:

1)Bad tank of gas
2)My last recalled was rushed due to incompetent dealership. Something may be loose under the intake manifold causing a "ping-like" noise.
3)MAF is slightly dirty
4)Plugs loose/Coil not making contact

 

The pinging has been going on for several months. I recently had the ECU reflash and the cam sprockets done. No changes to the plugs. I imagine the only way the plugs would make a difference is if you changed the heat range to a hotter plug. I think it is a lean condition that is inherent to the stock ECU closed loop mode, while trying to maximize the fuel economy and minimize the pollution. I fix it by putting my boot to the pedal. The pinging goes away when I give it a little more throttle. My car only pings when I am very light on the pedal around 40mph and the trans is in a higher gear (maybe 4th).

 

True, true. It is kinda odd. I wonder if one of the reflashes has caused this?

So far, I have had all recalls and:
1 Reflash for hesitation
1 Reflash during O2 sensor replacement
1 Reflash for sunroof (probably not related, but programmers make mistakes).

I don't recall hearing the noise until after my last recall, however I had the hesitation TSB done about 2 weeks prior so it is hard to say.

This is exactly what mine is doing. A little throttle and it goes away.

 

It pinged before and after the last ECU reflash.
I had it for the hesitation TSB.
Funny you mentioned the sunroof. They replaced the slide switch on mine to fix the sunroof TSB. Dang thing opened by itself while it was parked at an airport. It was a cold snowy day, so I couldn't possibly have left it open.

 

My sunroof refused to close and made a noise twice like it wanted to open. I tried resetting the module but nothing worked. After the reflash, no problems.