Power Fc, Datalogit, And The Ugly Bitch, Knock.

[The Mafia]

Couple of Questions:

Car is a R33 Nissan Skyline, with a RB25DET, and Garrett GT30 making

around 250 rwkw.

1. The Knock setting area on the Fc Edit Software under the settings 1

tab. There is a "Thresh" which is what it will flash on the dash with

if there is knock.

What does the "setting" reflect. On the RB25 default maps, its set at 9.

Also, My Knock sensors are reading 80 - 100 on some parts of full load,

and the tuner says he can't hear any knock.

He does quite a few XR6 Turbos, and says that he has to turn off his

knock sensors all together because since he's making so much more

power, the sensors are picking up general engine noise as knock. He

also said since the engine is making so much more power, it sounds

different and can fool the knock sensors into thinking its knocking.

(this XR6T is 11.5 @ 120mph Standard motor and turbo! Seen it with my

own eyes)

The main reason he turns off knock sensing is because then the factory

ECU tries to pull out 6 degrees. They actually edit the Factory ecu to

gain power.

Anyway... Could my sensors be over sensitive?

Since the water methanol Injection has been fitted, its making heaps

more power. I want to put the timing in, but I am too scared to because

the sensors are reporting high knock (when we can't hear it).

All input, big or small, is appreciated.

Thanks

Jono

[rob82]

Couple of Questions:

Car is a R33 Nissan Skyline, with a RB25DET, and Garrett GT30 making

around 250 rwkw.

1. The Knock setting area on the Fc Edit Software under the settings 1

tab. There is a "Thresh" which is what it will flash on the dash with

if there is knock.

What does the "setting" reflect. On the RB25 default maps, its set at 9.

Also, My Knock sensors are reading 80 - 100 on some parts of full load,

and the tuner says he can't hear any knock.

He does quite a few XR6 Turbos, and says that he has to turn off his

knock sensors all together because since he's making so much more

power, the sensors are picking up general engine noise as knock. He

also said since the engine is making so much more power, it sounds

different and can fool the knock sensors into thinking its knocking.

(this XR6T is 11.5 @ 120mph Standard motor and turbo! Seen it with my

own eyes)

The main reason he turns off knock sensing is because then the factory

ECU tries to pull out 6 degrees. They actually edit the Factory ecu to

gain power.

Anyway... Could my sensors be over sensitive?

Since the water methanol Injection has been fitted, its making heaps

more power. I want to put the timing in, but I am too scared to because

the sensors are reporting high knock (when we can't hear it).

All input, big or small, is appreciated.

Thanks

Jono

What he should be doing with the xr6T is de-sensitising the Knock sensor gain functions rather than turning it off completely. XR6T factory ecu can pull up to about 8 degrees if they feel necessary. It only takes 1 bad batch of fuel to cause damage. I definately wouldn't turn the knock sensor off in a customers car thats for sure.

I wish it where possible to tune the knock senistivity of nissans but its just not possible using PFC or factory management. I've found the nissan sensors fairly consistent in the topend at high load however there have been a few that I wish I could have desensitised. If he is happy enough that there is no detonation then be happy that its a safe tune. Get him to read the plugs after 1000k's to determine if there is need for a tidy up of the timing map. I've found that you have to be very progressive with your timing numbers throught the map as large variations in timing can give you a knock also.

[paulr33]

the 9 referes to the flasing sequence it uses to run when the level is reached, 9 means flashe 3 times at 0.1 second intervals

i would be trusting the logic of the knock sensors and not ignoring them

[The Mafia]

i would be trusting the logic of the knock sensors and not ignoring them

they are too sensitive.

I've getting readings at 40+ and not hearing any detonation.

Can anyone agree with this?

[paulr33]

well you can ignore the value if you wish

not sure if it will go bang or not

[rob82]

I found points that are quite audible though a chassis ear and to well trained ear external to the car. The knock reading on the hand controller was zero. I have found this on quite a few cars now.

[Birnie]

Only had mine tuned for the first time in the last week by The Hitman.

The Power FC is set to flash at over 60 i think.

I get a small patch of flashing when at full load at about 3.5-4k revs. (hits about 80)

Hitman also said that he doubts you would be able to hear that and in the 'old' days, no one would have worried about it.

I might ring him later in the week and ask if i should do anything about it because it's always the same spot.

[Guilt-Toy]

Mine has been knocking at over 100 for the last 2 years and I have NEVER been able to get it to stop reading knock.

Every time i hammer it i will get a reading from 30 - 100 no matter who tuned my car - if i do it myself or if i get someone else to do it nothing changes.

C&V Tuned my car last and he said to ignore the knock sensor readings because its not knocking on the dyno but it is reading high knock.

I would really like to get this fixed and get some kind of readings happening again so if it does actually knock I will know about it.

I noticed that my knock sensors started to read high knocks after i got over 300rwhp - when i had less then 300rwhp it was not sooo sensitive.

[Robo's]

I too get some hi knocks, sometimes in the 90's but cannot hear it ping at all like the old days. If i put some optimax extreme this comes down to 60. I live with it, this is only on hi boost, low boost gives me around 30. Starting up gives me knock of 40.

[Guilt-Toy]

Start up knock of 40 ? woah mine goes up to 10 on startup.

I did hear that if your knock sensors are screwed in too tight it can be very sensitive. I put mine on pretty much finger tight and it made no difference.

Anyone have any ideas how to get knock sensors working properly???

I too get some hi knocks, sometimes in the 90's but cannot hear it ping at all like the old days. If i put some optimax extreme this comes down to 60. I live with it, this is only on hi boost, low boost gives me around 30. Starting up gives me knock of 40.

[GTR1993]

Iv had experience the other way on my GTR, when i got it and was retuning it up top there was a big knock (at only 17 deg ignition advance) clearly could head it and the power fc didnt pick it up at all.

[Cristian]

Ive had a knock reading of 23 and was able to hear it, but on the other hand i have had a few knock readings of 200 odd and havent been able to hear a thing.

I cant work it out!

[Guilt-Toy]

I have seen mine read 150 or even 211 once...

Be nice to fix it....

[Sydneykid]

Based on my experience the PFC knock sensor numbers are a combination of loudness and frequency. If you have a loud knock, that doesn’t occur very frequently, you can get the same reading as a soft knock that occurs often.

For example, if you have one cylinder knocking loudly you can get the same display as if you have all 6 cylinders knocking softly. Obviously a soft knock at 6,000 rpm may give a similar reading to a louder knock at 3,000 rpm.

So saying stuff like I get “100 knock sometimes” is not at all useful for your tuner. You need to be able to tell him at what rpm, what throttle position and what sort of load. If you have a Datalogit this is obviously very easy to do from the log. If you don’t have a Datalogit, then the best method I have found is to set the Commander for 4 displays. Being knock, rpm, TPS and AFM voltage. When the dash warning flashes, I can see the knock reading and remember what the other outputs are at that time. This is obviously easier with a passenger or a video camera (the poor mans data logger) pointed at the Commander display.

It is so much better to say to your tuner, I get 80 knock at 5,500 rpm with 100% throttle and an AFM load showing 4.5 volts. That tells him where on the fuel and ignition maps to start looking.

cheers

PS; if you get reduced knock when you use 100 ron (compared to 98 ron) then chances are that is REAL knock and should be attended to.

[Chris32]

I have had this problem for over 2 years now

I have had it tuned and tweaked so many times, and its still the same

I believe, along with my tuner, that my knock sensors are indeed playing up. Ever since pulgging in the FC-Logit stuff, the knock sensors have played havoc. Doesn't matter what we do, 10* or 18* timing at full noise, it knocks to about 80 at WOT at around 5400rpm

No noise, no puff out the exhaust, just on the hand controller. The rest of the run is at around 25-40

To the point now where I don't even drive with the hand controller plugged in!

I reckon its something to do with FC-logit, but what I have no idea

[Sydneykid]

I have had this problem for over 2 years now

I have had it tuned and tweaked so many times, and its still the same

I believe, along with my tuner, that my knock sensors are indeed playing up. Ever since pulgging in the FC-Logit stuff, the knock sensors have played havoc. Doesn't matter what we do, 10* or 18* timing at full noise, it knocks to about 80 at WOT at around 5400rpm

No noise, no puff out the exhaust, just on the hand controller. The rest of the run is at around 25-40

To the point now where I don't even drive with the hand controller plugged in!

I reckon its something to do with FC-logit, but what I have no idea

Only once I have had a similar problem, that was at 5,250 rpm in an RB30. What I did was set the ignition timing from 4,500 rpm to 6,000 rpm at zero and richened up the A/F ratios to 10.5 to 1. That totally eliminated any chance of real knock. 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.

Every other time I thought I had phantom knock, it went away with the extreme rich and retarded settings. So it was real knock, and needed to be tuned out.

The answer is there, you just have to be prepared to spend the time looking for it.

cheers

[paulr33]

tops, will add to faq tonight re: knock and debugging it