Knock level on power FC

[quentinchan]

How is everybody doing today? I have a question on PowerFC. I am wonder what is everybody else' peak knock level on their power FC is showing. Mine is at 19, I want to figure out is it normal before I blow my motor. Thanks alot of your help.

[proj240sx]

it shows in the US manual for rx7s that the max ping u before damage is 60. ive heard from other people it is the same for us..but not too sure since it can pick up other noises that sound like detonation.

[bauchrb]

I'll have mine in today and on tomorrow. I'm runnin a RB, but I'll let you know what happens.

[Evil240]

mine never passes the mid/halfway point... never looked at the numbers.. but i will do it tonight.

[johngriff]

Dont believe that knock sensor reading, it is not very accurate if you are not stock.

I have seen a tubular manifold bring the knock up to 50. The engine was not actually knocking, just a different vibration that it read as knock.

It is on a scale of 200 (which does not make much sense apexi), so evey 2 is = 1%.

Try playing with you timing to see if you cannot trim the knock. But there are also 9mil other factors, that you would need a dyno, af/r, egt/ spectral analyzer to actually know where the knock is comming from.

Summary: Go to dyno, get tuned.

[Canaduh]

Johngriff, if you wrote a book, i'd probably buy it.

[Wei240]

i've never gone past 20 on peak, (you have to use the peak to see a value, otherwise you see is a bar)

yeah, if you have alot of aftermarket parts, it may 'sense' a knock differently...

[quentinchan]

I have a SR20det zenki, from time to time it would read 24 on knock level. So I m pretty much worry! HELPPPPP!

[Wei240]

umm, might want to post your setup,
and who tuned your car


forget it,

just go tune your car, better pay now for a REAL tune or potentially rebuild your engine later...

[johngriff]

LOL, thanks. There really are too many factors.

Years ago, A car I used to have had a "high" knock reading (40 on apexi thing). After messing with the timing, I went to the fuel, richened it up, and it took away the knock, but then, it was far too rich.

Testing the injector circuit showed bad connectivity in the no 2 injector. I added 1% trim to that injector, and dropped the knock down to a peak of 3. I figured it was an unbalanced injector or bad solenoid.

Later, i replaced the whole harness with a new OEM one, and reset the power fc. I found that the knock was gone and at 3 peak. It had actually been the grounding wire the whole time (on the efi harness).

Case and point: You can go through alot of odd diagnostics trying to correct the knock, it could be caused by a myriad of things. A good dyno shop will get right down to the root of your issue quickly, and the least costly, when adding up friends, time, and tuners without resource to accurately diagnose your issue.

quentinchan: Go to autowave in HB. They use a dynodynamics dyno, and are very good at what they do. Quite reasonable as well.

And thanks for the compliment, though i dont think i know enough yet to make a *GOOD* book. One of my favorite reads by far was; "The scientific design of intake and exhaust systems". This is an awesome place to start. And of course, lurking on efi101.com

[quentinchan]

Ok... The reason it has me worried is because I took my car to some tire place in OC. They messed around with my car's setting. So I started pay more attention to my knock level. But I talked to my tuner. He said if the knock level ever reach 40, that would be bad. When the knock level got to 60, the check engine light would start blinging. So 20ish would be ok. Thanks for everybody's help anyways!

[s13silvia123]

this might help is you have this

1. Use temporary IGN adjust
Drive around and replicate the concering knock levels, be sure to note roughly where it happens (rpm or load etc).

SETTING -> INJ/IGN Adjust -> Press DOWN 3 times and you will see -3 for IGN ADJUST. This drops the IGN map 3 degrees timing temporary (will reset when car is powered off).

Drive around and try to replicate the knocking levels again, be sure to try and reproduce the engine load and rpm you did previously. If the knocking has dropped considerably or has gone away completely (very likely) then it is simply a few cells on the IGN map have too much advanced timing.

You should give this information to your tuner;

Max Knock of: 50
At RPM: 4700
At Engine Load: Max Load (throttle was nailed)
Using Fuel: Standard BP Premium
Adjustments: -3 deg IGN timing fixed the problem

The tuner then has enough information to drop onto the IGN map and take out 3 deg timing where 4700 and max load lands on the IGN map. Should take no more than 5 minutes to correct and all be happy. The blanket and braindead approach is to drop the whole map 3 deg either using Datalogit or dialing the crank angle sensor backwards a notch, this is NOT recommended as its braindead. You have stand alone engine management, it should be used like one.


2. Use higher octane fuel
Drive around and replicate the concering knock levels, be sure to note roughly where it happens (rpm or load etc).

Find a local service station with really high octain rated fuel, Shell Optimax Extreme is a good one. Plonk in a full tank of Optimax Extreme and drive around for about 15-20 minutes to get the fuel flowing.

Drive around and try to replicate the knocking levels again, be sure to try and reproduce the engine load and rpm you did previously. If the knocking has dropped considerably or has gone away completely (very likely) then it is simply a few cells are possibly too lean on the INJ map (could also be IGN timing). Running a much higher octane rated fuel is likely to take away some detonation.


3. Adjust IGN map
Drive around and replicate the concering knock levels, be sure to note roughly where it happens (rpm or load etc).

You should give this information to your tuner;

Max Knock of: (highest level you saw)
At RPM: (what RPM you noticed the engine check light come on)
At Engine Load: (driving conditions)
Using Fuel: (what fuel you used)
Adjustments: -3 deg IGN timing fixed the problem

The tuner then has enough information to drop onto the IGN map and take out 2 degrees timing where your driving conditions land you on the IGN load map. Should take no more than 5 minutes to correct and all be happy. The blanket and braindead approach is to drop the whole map 3 deg either using Datalogit or dialing the crank angle sensor backwards a notch, this is NOT recommended as its braindead. You have stand alone engine management, it should be used like one.


4. Blanket approach
The blanket and braindead approach is to drop the whole map 3 deg either using Datalogit or dialing the crank angle sensor backwards a notch, this is NOT recommended as its braindead. You have stand alone engine management, it should be used like one. Lowering IGN timing is likely to take away any detonation but will certainly give the engine a flat and empty feeling (not recommended).


5. Ground Zero approach
Set the IGN timing from 4500rpm to 6000rpm at zero degrees.
Set the INJ map from the same load areas to 10.5 to 1 (mega rich).

That should complete eliminate any knocking, that is it is not humanly possible for it to knock now. Do a max load dyno run (damn it will be boggy and make jack all power) and see what knock levels you get now. If you still see knocking then its likely the sensors are picking up other mechanical noises in the engine bay. Using a chassis ear tool would assist in debugging where the noise is coming from.

One owner reports;

"Then I went for a little walk around the engine bay on the dyno with the chassis ear. It turned out to be the remote oil filter sandwich plate tapping on the oil pressure gauge adaptor. They were located right under the rear knock sensor. There was obviously was a slight engine vibration at that RPM, which I later traced to an unbalanced pressure plate."

So it certainly is possible for other external factors to cause "knocking" and thats the Ground Zero, rule out everything else approach.

[johngriff]

Nice,

You should have at least cited:
http://paulr33.skylinesaustralia.com/docs/powerfc-faq/powerfc-faq.htm

Its not cool to copy pasta without citing the body of work you are doing it from.