Knock In Low Load

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hi guys and girls,

i was wondering if anyone has experience the high knock (20-30 on PFC) in low load (ie. less than 3000rpm) straight after replacing my 40000km old iridium plugs with copper plugs? never have knocks above 10 with the iridium plugs...

thanks

[89CAL]

what heat range did you use? maybe try going to a cooler plug or double check you put the right gap in them?

[The Dan]

Does it ever go over 30?

If not, then stop worrying

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Does it ever go over 30?

If not, then stop worrying

NO, but this is at low load (below 3000rpm), shouldn't it be less than 10 counts.

I replaced the plugs with the same heat range.

[STATUS]

its fine unless you fitted the wrong plugs.

[paulr33]

its fine

remember you can have too high knocking, and too low knocking, ie if its too low aka zero, its not tuned hard enough

[Dale FZ1]

you can have too high knocking, and too low knocking, ie if its too low aka zero, its not tuned hard enough

Got to disagree with you there Paul. If it's knocking, it's bad. Full stop. Knock kills engines.

The issue is if a sensor output of 30 is actually knock, or "general noise". Use of a proper stethoscope and comparing against observed readings is the way to really determine that.

However I would look to keep those readings less than 30, and less than 20 under high load areas.

Edit: reading the OP, you need to identify if it is high LOAD, or high RPM. They are different axes on the map. And if you are reading off the hand controller there is no way of readily identifying which cells are the offenders.

Has anything else changed, including a fresh batch of fuel just after the plug change that might be of questionable quality? Sometimes the cause of things you observe isn't always evident immediately.

Edited January 3, 2010 by Dale FZ1

[Kwyjibo]

No matter how much timing I pull out I always get knock up to about 35. I've had people listen to it on the dyno and we weren't able to hear any pinging when it would get up to this level. On full throttle it usually only gets to 25. The time it jumps up to 30 or above is when I back off the throttle. It has done this for quite awhile and I still haven't melted any pistons.

[Dale FZ1]

Hence my comments above. The sensors are just a microphone that converts vibrations to an analogue signal. There will be variance between sensors as to what output signal is thrown to the ECU is associated with actual knock.

However, common consensus seems to be that numbers at 20 and lower are distractors. If the OP was concerned, he should be having some action taken with a stethoscope.

[JonnoHR31]

i always get knock reading at the exact point i back off, unless they're huge numbers, ignore them.

OP: try taking a couple of degrees out accross the board in the temp adjustment, if it still does it then it can be ignored, if not then it probably needs 1 or 2 degrees dropped out in 1 or 2 cells. 20-30 is probably fine but it might be lightly pinging, which isnt desireable

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thanks for all you help.

i have replaced the plugs with BCPR6ES. The knock counts jumped to from 8 to 23counts in the first 10 cells low rpm and low loads.

The high loads knock count was 19 max. ie not the fuel problem.

Since then i have got myself a datalogit and i have reduced the timing by as high as 8 degrees to see the knock count dropped to 8counts...

From some of your comments in the low loads/rpm the knock count can go as high as 20... Could you please confirm?... i have read somewhere saying the the first 10 cells loads/rpm should keep the knock count less than 10... i could be wrong... My high loads have never gone pass 20 ever.

once again thanks.

[JonnoHR31]

if you had to take 8 degrees out then its unlikely it was pinging. use the graph function to go through and see exactly what knock readings your getting and where, its useful for sorting out random spikes from proper knock

[R31Nismoid]

Got to disagree with you there Paul. If it's knocking, it's bad. Full stop. Knock kills engines.

Gotta disagree with you on that one

Not often I disagree with you either…

Paul’s point was there must be “some” noise on the knock sensor. If there isn’t there it is clearly fubar and not reporting correctly.

You have to have noise, that is what combustion is.

What is “normal” for a RB knock sensor is anything from 10-30 @ any part of load/rpm/map.

Much more than 30 and you probably need a cell or two that needs attending too…

OR… one of the other two options.

1. Your knock sensor is fubar

2. Your knock sensor is picking up other noise, ie a loose starter motor or something rattling around, or thats just 'how it is'. Sometimes they just pickup 40 no matter what!

[The Dan]

Low load knock levels up to 100 won't hurt anything.

And like was said above, knock can be caused by many different things so make sure it's not just interference. If you have 20 knock below 3000rpm, that is the best place to have it if you've gotta have it somewhere. At those engine loads it can simply not be doing any damage.

Drive ANY new manual car and put a knock box on. You'd freak out if you saw the knock levels when you stand on the accel or take off from the lights. But because it's at low load, it's fine.

[The Dan]

Gotta disagree with you on that one

Not often I disagree with you either…

Paul’s point was there must be “some” noise on the knock sensor. If there isn’t there it is clearly fubar and not reporting correctly.

You have to have noise, that is what combustion is.

What is “normal” for a RB knock sensor is anything from 10-30 @ any part of load/rpm/map.

Much more than 30 and you probably need a cell or two that needs attending too…

OR… one of the other two options.

1. Your knock sensor is fubar

2. Your knock sensor is picking up other noise, ie a loose start motor or something rattling around, or thats just 'how it is'. Sometimes they just pickup 40 no matter what!

+1

tap a spanner on your intake runner gently and watch it go through the roof.

Rattling clutch, alternator, timing belt bearing, water pump can all be causes for 'noise'.

And so can the beginnings of a spun bearing.

OP: Don't treat it as nothing, just don't be overly concerned about it. And take it somewhere that has an electronic steth they can hook up or a knock box to put your mind at ease. Every engine is slightly different in frequency so your ECU might read worse on a different engine, it might read better, but the point is the readings are normal.

[Mangune]

Whats a safe KnK reading? I got a SAFCII an it varies i can run on 0-5 (generally on cooler day) an up to 40 on hot days.

I dont kno much about the whole Knk thing can anyone enlight me?

Cheers

[.WILKO.]

I started getting a slight high count on my r34, 25-30, then one day i got a random 150 on my power fc!!! but the car was running sweet no pinging at all (and at 150 the car would hardely run).

i took it straight to my tuner and he took out a shit load of timing as a saftey precaution. he had the thing for a week checking different things done so many power runs it wasnt funny. out of every 5 runs he would get a wierd 100+ count but he had his own knock detection set up and heard nothing i was even there!

the motor has forged internals so should withstand higher than normal knock but no knock is the best, car runs sweet tho...

but any ideas faulty sensors etc?

[JonnoHR31]

were u on limiter when it was giving you high knock readings?

[.WILKO.]

nope around 5500-6000, but in sayying that i have had it on the limiter and had a high reading.

[JonnoHR31]

could be anything rattling in the engine bay near the knock sensors, or could just be a rooted sensor.

knock readings on limiter are almost always false, if its been tuned properly it should have a touch less timing on limiter for safety, not like you need lots of power up there anyway