Stupid Scanmaster question

[4cd-Air]

I am pretty new to using my scanmaster, and I am getting a knock reading at 10 lbs of boost and up. Is there any way I can check to see if this is false knock? I have had this problem for months. Fuel pressure is 38 psi at idle, 43 at 2000rpms and goes up 1 psi per lb of boost. Just cleaned engine with Top Engine Cleaner. Shouldn't you be able to hear the knocking? When it reads knock, I hear no change, and the knock goes really high, starting at maybe .8 all the way to 11.5-14. I cannot figure out why.

 

[Mile Hi GN]

Originally posted by 4cd-Air
I am pretty new to using my scanmaster, and I am getting a knock reading at 10 lbs of boost and up. Is there any way I can check to see if this is false knock?

Yes,

The best way is to put in some race gas. The high octane fuel will quiet the real motor knock - so if you continue to see knock with the race gas, good chance it's false. Might even try a high content of Xylene as a substitute.

Originally posted by 4cd-Air
Shouldn't you be able to hear the knocking? When it reads knock, I hear no change, and the knock goes really high, starting at maybe .8 all the way to 11.5-14.

I've heard that it takes around 16 degrees of retard until you can actually hear pinging. So not being able to hear anything at the retard levels you describe makes sense.

I've seen all kinds of retard on the street but I don't think I've heard an actual "ping" in years.

Originally posted by 4cd-Air
Fuel pressure is 38 psi at idle

Is that with the line on or line off?

What are your O2 numbers when you access SM2's recall?

You might try adding some more fuel pressure and see if that helps.

 

[4cd-Air]

What is considered a safe amount of knock? Like whats the highest number it can safely read? I am gonna try some Xylene soon. Fuel pressure was 38 at idle with the line on, like 43 with it off. How can I adjust fuel pressure? I would like to turn it up to be safe. How do I check the recall?

 

[325DR]

Originally posted by 4cd-Air
What is considered a safe amount of knock?

I will not allow any more than 3.0 with pump gas, and 1.5 on race gas.

How can I adjust fuel pressure?

Assuming you have an adjustable fuel pressure regulator, on the top of it, there will be a nut with a screw coming straight out the top of the regulator with an allen fitting on top. Loosen the nut, then turn the allen screw clockwise until you get to about 43-45psi with the vacuum line plugged. You can do this by disconnecting the vacuum line, put your finger over the end of it so you hear no suction, and then set the FP so the gauge reads 43 or so.

How do I check the recall?

On the scanmaster, you can press and hold the left button (which says recall) to see your lowest O2's and your highest knock retard. It will only display something if you reached WOT, so you will have to floor the car to get it to show any recall when you are done. Hope this helps...