Rattling noise in my engine

nissan
murano

#1

When i step on the gas there’s a rattling noise in the engine like it’s starving for gas but when i put super unleaded in it goes away. I can’t afford super all the time!


#2

What is the model year of your Murano?
How many miles are on the odometer?
Is the engine running hotter than usual?
When was the last time that the spark plugs were replaced?

If the spark plugs are not overdue for replacement, then the first thing that I would look at is the EGR valve.
An EGR valve that is too gunked-up to function properly will lead to “pinging” when you accelerate.


#3

Yes, it does sound like a pinging problem. Best to keep using the super until this is resolved/ b/c what will happen to your engine is closely related to your handle if the pinging is allowed to continue unabated.

Various things can cause pinging, but start with the simple. I had some pinging in my 90’s econobox Corolla and I discovered the spark plug gap had widened over time. Replacing the spark plugs fixed the problem. Ask your mechanic to check the condition of your spark plugs and measure the spark plug gap.


#4

Is the gas you’ve been using a Top Tier gasoline?

http://www.toptiergas.com/

If not, carbon can build up on the valves/pistons which can cause a lean condition/pre-ignition causing pinging.

Tester


#5

Carbon build-up can indeed cause “pinging”…If a cure can be found in a can, that can would be labeled BG Formula 44K…Otherwise, the knock sensor, which should send a signal to the computer requesting the spark timing be retarded a little, is not working so the ECM advances the timing more than it should which produces the pinging…Only shops with the most advanced equipment can diagnose problems like this…Lesser shops and most DIYers just start throwing parts at the problem until it goes away…This can get expensive.


#6

I agree that this sounds like definite pinging. The effect of premium fuel is a dead giveaway.

But without a lot more information we’re all just throwing wild guesses.

The first thing I’d want to know is the year… and whether the engine requires premium fuel, as many modern engines do. Your owner’s manual will tell you this.

Besides knowing the fuel recommendation, the year can tell us whether the engine uses an Exhaust Gas Recirculation system to help control pinging or instead retards closure of the exhaust valves using the variable valve system, as many modern engines now do.

I’d also want to know the mileage and the maintenance history. Carbon buildup can cause pinging due to carbon’s tendency to retain heat, creating a hot spot in the cylinder. However, on a properly maintained and non-oilburning modern engine, carbon buildup is rare. Whoch brings me to the maintenance… how old are the plugs? When was the last plug change done? And what did the old plugs look like?

And speaking of oil burning… how much oil does it use?

Is this engine turbocharged? If so, the elevated pressures in the cylinder will require premium whether you can afford it or not. I’m unfamiliar with the technical specs on a Murano, so bear with me.

And the recommendation to use premium until the question is resolved is spot-on. Prolonged pinging can burn a hole in a piston. And it can also case other damage. Pinging is the clash within the cylinder of the spark-induced explosion with a self-induced explosion caused by excess heat. It creates a shock through the piston, the wrist pin, and the rod bearings.

One other question: have you had the ECU scanned for fault codes? EGR malfunctions and knock sensor malfunctions, as well as irregular explosions detected by the knock sensor, will store “fault codes” in the ECU. That’d be a great place to start the search for an answer.


#7

Maybe the rattling is related to a problem with the timing chain, variable cam timing mechanism, etc. which may in turn be related to the oil change regimen.
That can have an effect on pinging.