knock question

[sharvinnp]

Hi all, I’ve recently noticed that my Stang is making a metallic rattling noise. Here is the audio. I’m hoping someone here with more mechanical experience can help confirm whether this is an issue with the purge valve. At the end of the day, this kind of noise shouldn’t be happening... and I want to make sure I’m taking the right steps. Thanks in advance for your help and insight

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[robvas]

You can easily confirm it yourself. We really can't over the internet.

Get an OBD2 scanner that can show live data. They are cheap on Amazon etc

Drive with it connected and see if knock shows up when you are hearing that sounds. Otherwise it could be the DI pump, engine lugging, or other "normal" noises.

 

[K4fxd]

Are you tuned? Stock it should never run into audible knock.

I couldn't hear anything on the video but the easiest way to find out is add 4 gallons of e85 to 12 gallons of 93. If the noise goes away it is spark knock. Could alternatively add 1 entire can of boostane but this is hit or miss due to the formulation of your local gas.

Running the tank empty and adding 5 gallons of 100 octane unleaded race gas will work the best.

 

[Pittpa]

I hear nothing. Any time stamp to listen for?

 

[Goterr0r]

What trans? What gear were you in at 30-40 MPH? Just making sure you are not really lugging the engine. Agree with the above. You need to log the data and see if this is actual knock. Positive number = bad. Negative numbers = Good. You can buy a bluetooth/wifi OBD2 adapter on Amazon for cheap and use an app on your phone like OBDFusion or similar if you don't have a tuning device that actually logs data for you.

 

[Goterr0r]

Something like this. https://www.amazon.com/OBDLink-Blue...qid=1755797355&sprefix=ob2+blu,aps,117&sr=8-8
and then download either an app called Torque or OBDFusion. You will want to monitor knock count. It will go to i believe +8 and -8 for the values. + is bad - is good. You will see if fluctuate, but if you are giving the car steady gas it "should" be going negative which means the car is adding timing. If its going + then its removing timing and you a number of things that could be going on to cause it. Poor gas, metal on metal causing vibration kicking the sensor up (false knock)

You can also buy a can of Boostane and run a few ounces and see if the noise goes away. If it does then try to start getting gas at a new station. I really doubt this is carbon build up causing it.

 

[GrabberBargeCaptain]

The car is 100% stock. I always fill up with Shell fuel - most of the time I fill up with 89, here in Los Angeles.

maybe try with 91 and see if it makes a difference, especially in the summer time.

 

[RNM]

The noise definitely fades away with 91. But that's my issue... whether I fill up with 87 or 89, it shouldn't be doing this in the first place especially given that Ford says 87 is OK.

Ford also says that the transmission fluid is good for the life of the car...

I see that common sense isn't so common.

Run 91 octane at the bare minimum.

 

[K4fxd]

But that's my issue... whether I fill up with 87 or 89, it shouldn't be doing this in the first place especially given that Ford says 87 is OK.

The car will run on 87, if you use the car at all put 91 or better yet 93 in it.

Not too long ago a 12 to 1 engine needed 100 octane to completely stop spark knock.

 

[robvas]

from the owners manual:

Have you confirmed that it is actually knock, according to the knock sensor?

 

[GR1MxREAPER]

Ford also says that the transmission fluid is good for the life of the car...

I see that common sense isn't so common.

Run 91 octane at the bare minimum.

No need to be rude to the guy… Ford clearly says the car can run 87 so if yeh guy isn’t racing or whatever and wants to run 87 he should be able too as ford engineers say it can be done.

from the owners manual:

Have you confirmed that it is actually knock, according to the knock sensor?

You literally cropped out the part that says “your vehicle is designed to operate on 87 octane” come on man…. If you’re gonna show a picture show the entire thing.

 

[RNM]

No need to be rude to the guy… Ford clearly says the car can run 87 so if yeh guy isn’t racing or whatever and wants to run 87 he should be able too as ford engineers say it can be done.





You literally cropped out the part that says “your vehicle is designed to operate on 87 octane” come on man…. If you’re gonna show a picture show the entire thing.

He says he hears a knocking sound when going 50% or more on the throttle and says that it goes away when he puts 91...

Again, common sense isn't so common.

 

[robvas]

You literally cropped out the part that says “your vehicle is designed to operate on 87 octane” come on man…. If you’re gonna show a picture show the entire thing.

Nobody said it wasn't able to run on 87 octane.

 

[GR1MxREAPER]

He says he hears a knocking sound when going 50% or more on the throttle and says that it goes away when he puts 91...

Again, common sense isn't so common.

No one is saying it isnt knock… it probably is. you said you need to run 91 … clearly you didnt read the manual as that isn’t true. Of course 99% of people run 91-93 octane. I was just stating that the manual says you can and some People do run 87 and are fine… which points to either bad gas or another problem with this guys car.

 

[GR1MxREAPER]

Nobody said it wasn't able to run on 87 octane.

The guy above literally just did bro . And you
Showed a picture with 91 gas highlighted . You can’t make this up.

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