What all might be causing knock?

[-DSM2NR-]

I'm sick of this. I can't even run 15psi on my setup without knocking even though I got a FMIC, injectors, fuel pump and all that good stuff....I run 92 octane which is the highest we got over here

What are all possible reasons that a car migh be knocking and how might this problem be fixed?

 

[alex]

Do you have any logged information?

 

[crazyboost]

Have you done a boost leak test yet? If not you really should, that could be causing some bad knock. go here:

http://www.vfaq.com/mods/ICtester.html

 

[nightspeed87]

also what about phantom knock or a bad knock sensor, you try that yet?

 

[-DSM2NR-]

haven't really checked the knock sensor since it's too damn tricky to get to. How do I know whether it's messed up or not?

I've heard that boost leaks could be causing knock but how? Would the leak cause the gauge to show only 15psi although it's actaully running more than that (lets say 21psi) since it's leaking? Or is there a different reason boost leaks cause knock?

 

[blackGSX2g]

No your boost pressure would still be 15psi, but your turbo would be working harder to maintain that boost pressure and you would be loosing metered air (running uncontrollably rich). Keep in mind your knock sensor will detect 'rich knock' as well. Post up some of your DSMLink logs either here or on the Link forum and we can help you from there.

 

[-DSM2NR-]

ok, I'll get my latest log posted once I get home.

 

[spatulahunter1]

What are all possible reasons that a car migh be knocking and how might this problem be fixed?

my sister had 9 qts of oil in here grandam that only held about 4 and that made it knock like a mofo hehe

 

[nightspeed87]

No your boost pressure would still be 15psi, but your turbo would be working harder to maintain that boost pressure and you would be loosing metered air (running uncontrollably rich). Keep in mind your knock sensor will detect 'rich knock' as well. Post up some of your DSMLink logs either here or on the Link forum and we can help you from there.

Does rich knock happen when it gets to the point that your running extremely rich?
Running rich isnt too harmful besides messing up spark plugs and diluding your oil right?

 

[-DSM2NR-]

Here's what's weird. Today I was driving the car for around 15minutes straight before doing a 3rd gear run. Knock stayed below 1.0.

Then I stopped somewhere to take a look at the log. After about 5minutes with the car standing still and idling I went and did another run. KNOCK WAS ABOVE 5!!!!!!!!?!?!! Wtf is this crap? On some runs there's barely any knock and on others there's major knock....... My A/F ratio is around 10.56:1. If I go any leaner than that I just get more knock counts.....

 

[95FlamingTalon]

On some runs there's barely any knock and on others there's major knock....... My A/F ratio is around 10.56:1.

I didn't see an fpr on your list of mods. Even with your walbro 190, you will slightly overrun your stock fpr. With the fuel pressure not being regulated, you're fuel pump voltage will vary from run to run, depending on the alternator speed, electrical accessories being run, etc. Therefore it will affect your fuel pressure and change your knock count every day. I've run into the same problem.
Or, of course, there could be a boost leak causing uncertain amounts of air to enter the engine.