Confused!!

[nissan n16]

Hi everybody, I am new here, and this is my first post. I have been surfing the internet for the past few days trying to find a solution to my problem.
I bought a second hand Nissan sunny n16/ 2009 six months ago. It was working just fine. However, a week ago a rattling sound started to be heard coming from the engine when the car is moving. The sound is continuous whenever I depress the fuel pedal regardless of the speed of the car even when it is stationery. I had the spark plugs replaced, but in vain!
I also used different types of fuel, again no use!
Any idea what is happening?
Engine: QG16DE
mileage: about 60000 Km/ 36000 miles

[Razi]

Welcome to Nico!
Is the car's power affected?

And the description of the sound is a bit vague, is it loud?
Could you perhaps take a video of this noise?
You say the sound occurs when the car is moving, but you say it can be heard when it is also stationary.
Do you mean the sound can be heard as soon as the car is turned on?

[nissan n16]

Thank you for your reply. the car's power started to degrade a month ago when I used a poor quality of fuel. however, after cleaning the in-tank fuel filter its performance was improved. with the coming of the hot season( it's around 110 F now) the sound comes and goes depending on driving conditions (going up a hill or accelerating between 60-80 km). mechanics said that this is normal because of the heat and the quality of fuel (which is sometimes sold as being super but turns out to be not so!). However, four days ago, suddenly the sound started to be continuous whenever i depress the fuel pedal. the sound increases with the acceleration.
The sound is engine knock or ping. it doesn't come when i turn on but when the A/T is on the P and i depress the fuel pedal I can here the knocking.

[Razi]

Hmm.
If its fairly loud, it could be rod knock.

However, with bad quality fuel, you could be getting predetonation, which wouldn't be as loud.

[nissan n16]

well, do you think that the bad fuel might be responsible for carbon deposits on piston which in turn causing predetonation?

[carloslebaron]

In my case, with a former vehicle I owned, a Chrysler Reliant, a similar problem happened, and wasn't only the quality of fuel but its octane. I went one step up in the octane grade of the fuel, and the sound disappeared.

[Dattebayo]

In my case, with a former vehicle I owned, a Chrysler Reliant, a similar problem happened, and wasn't only the quality of fuel but its octane. I went one step up in the octane grade of the fuel, and the sound disappeared.

Read the post, you fool!

Anyway, so it only happens when the car is moving? Or can you rev the engine while parked and get the same noise?

[nissan n16]

"Anyway, so it only happens when the car is moving? Or can you rev the engine while parked and get the same noise?"

well basically yes. the sound comes only when I accelerate while the car is moving. However, when the engine is hot, like after driving for 20 minutes, and while it is stationary, the sound comes when I rev between 2500-3000.

[skydragoness]

Where do you live?
Can you take it somewhere else for a 2nd opinion? I would do that. Take a video also.
It's not throwing any codes?

[Dattebayo]

It may not actually be coming from the engine... So check your heat shields on the exhaust. If one of the connection points has rusted on any of them, they expand when heated and can rattle around sounding like it's on the engine when actually right below it.

Next, how long has it been since the oil was changed? Is the oil low?

You have a timing chain system on that engine, correct? If so, then maybe there is a clog in the oil pressure tensioner for the timing chain. If you're not too mechanically inclined, you would need a mechanic to do this.

[nissan n16]

skydragoness :
I live in Iraq. "It's not throwing any codes?" sorry i did not get what you mean.

Dattebayo:

I change the oil every 800-1000 km, and the filter every 2000 km, and the level is as it is supposed to be. I am going to check the exhaust to see if something is wrong there.
As for the time chain, you are right both as it is a chain and as being not mechanically inclined. This is beyond my knowledge.

Thanks for both of you.

[sbird1]

My fist thought on the noise is heat shield. My dad's old car would do the same thing: only rattle at a certain RPM. But that does not explain a loss in power. "Throwing codes" just means that the "check engine" light is on. If it's on, you can hook up a code reader to your OBD II port under your dash and it will tell you why the computer turned the light on. Good luck!

[Dattebayo]

Just another thought, but it also could be the transmission, not the engine. If you had a bad torque converter or anything else in the trans, this could account for loss of power and movement-associated noise.

[nissan n16]

Hi everyone. I have inspected the exhaust and the heat shield, both are ok.

I had the time chain inspected, and it is ok also.

The Check Engine Light is off; no codes.

As for the transmission. Is there anything to check to see if something is wrong with it. When i start the engine the A/T light comes on for few seconds then it goes off. When I shift the gear it seems to be working properly.

[carloslebaron]

In my case, with a former vehicle I owned, a Chrysler Reliant, a similar problem happened, and wasn't only the quality of fuel but its octane. I went one step up in the octane grade of the fuel, and the sound disappeared.

Read the post, you fool!

Changing quality and octane of gasoline worked in my vehicle two weeks after the change, the dude who started this thread said that he used different types of fuel, but he doesn't specify for how long each time.

And please my beloved online cybernetic cheap mechanic, don't call me fool and show more respect, next time call me Mr. fool...understood?!

[Dittoz7]

Well everything I was gonna suggest has been already been dismissed. Video of the noise would be the next best thing in this mystery.