logger shows knock at 43

[darkstar1313]

logger shows knock at zero at idle, when i take off knock always jumps to 43. As long as i am on the gas knock stays at 43 if I let off it goes to zero. O2 sensor seems fine cycles until WOT then stays at .89V. What could be the problem, what can I fix.
Thanks for all the help, it is sad all the mechanics in my area and everyone at Auto Zone do not know what an eagle talon is. I have learned a lot from the site, and it has saved me lots of money. Keep up the good work.

 

[92_75i]

I've had the same problem on my logger too, almost the same exact numbers too....when I got the DSMLink it was a different story, but even on there i get knock at like 34% throttle and all this other crap....

Did you check your knock sensor? It's common for them to go out, or it could be phantom knock.

-az-

 

[yokotabrat]

Does it do it only at WOT, or partial throttle? If it does it at WOT, have you tried turning the boost down to see if it decreases?

The knock sensor is basically a sensitive microphone. If you think of it this way it might help diagnose your problem.

First thing is to determine if the knock is real. Usually the easiest way is to get a hold of some race gas and put that in (don't use octane boosters, most don't work). It's better the less it's diluted with pump gas, so either drain your gas or fill it with race gas when it's low.

If your knock goes down with race gas, it's probably real. At this point I'd check fuel pressure, fuel filter, plugs, etc. Log fuel trims if knock is more prevalent at partial throttle. If it's only at WOT, log air temp, air hz, and barometric pressure to make sure everything looks good there.

If race gas doesn't help, then it could be mechanical. The most common is noisy lifters. Anything that makes a lot of noise could potentially set off the knock sensor.

Hopefully this helps get you started.

 

[napkinthief]

Does it do it only at WOT, or partial throttle? If it does it at WOT, have you tried turning the boost down to see if it decreases?

The knock sensor is basically a sensitive microphone. If you think of it this way it might help diagnose your problem.

First thing is to determine if the knock is real. Usually the easiest way is to get a hold of some race gas and put that in (don't use octane boosters, most don't work). It's better the less it's diluted with pump gas, so either drain your gas or fill it with race gas when it's low.

If your knock goes down with race gas, it's probably real. At this point I'd check fuel pressure, fuel filter, plugs, etc. Log fuel trims if knock is more prevalent at partial throttle. If it's only at WOT, log air temp, air hz, and barometric pressure to make sure everything looks good there.

If race gas doesn't help, then it could be mechanical. The most common is noisy lifters. Anything that makes a lot of noise could potentially set off the knock sensor.

Hopefully this helps get you started.

This guy should not have newbie status.

I would say if its ALWAYS at 43, your sensor is bad. If it was mechanical, it should change based on your rpm, higher rpm = faster lifter movement, more phantom knock, more everything.

 

[darkstar1313]

The knock jumps to 43 anytime I press the throtle, it's there at partial throtle and at wot. I believe it is the sensor not an internal defect, simply because the engine runs smoth. As far as boost goes how would you turn the boost down on a stock engine? I live in a small hick town in Arizona, Were could I find 100 octane fuel. Also, I will check the knock sensor when I get home for what has been desribed as goo. Thanks for your help.

 

[darkstar1313]

If the sensor is bad what would happen if I disconnected it.

 

[yokotabrat]

If your knock rails to 43 at partial throttle, the odds are pretty good that it's picking up mechanical noise or the sensor is bad. I'd still make sure your fuel trims are in check to make sure that isn't causing some of the knock. If you still want to try high octane, you could try to mix your own octane booster. There are recipes on the internet in quite a few places.

If you're stock, you can't really lower boost too much. If you disconnect the boost control solenoid and run a line directly from the turbo outlet to the wastegate, that'll get you as low as you can go (unless you disconnect the wastegate arm).

Disconnecting the knock sensor would probably not be a good idea. If you do that, you'll get a check engine light and then the ECU automatically keeps knock sum at 9 or so to provide for some timing retard. If it's real knock, though, you want the knock sensor in there to retard timing so you don't blow your engine.

About the only way to know if the knock sensor is bad is to replace it. Same with lifter noise. I've seen some cars that don't make much noise, but replacing the lifters fixes their phantom knock. Of course, I've also seen some cars where it doesn't fix it. Good luck!

 

[darkstar1313]

Well I got under the car and checked the knock sensor. There was some kind of goo that had leaked out of it, so I will be replacing the sensor and see what happens. Thanks