How To Check For "knocking"

[RBFIRE]

Hi,

I got some mod done to my R33, Gtst

-batml split dump

-r34 intercooler

-35 bucks boost controller,

-K&n air POD

-3.5" cat back

i boost it to 10psi, but somtime spike to 11 or 12,

I am not sure if it will hurt the engine,

i wan to check if any detonation occurs

how to tell if my engine is knocking or not? i did ecu diagnose, i got code 55, which means all good?

cheers,

darrien

[paulr33]

knock sensors work in real time, ie while you are driving they will be reading "knocking" and sending that signal to the stock ecu. the stock ecu will deal with it accordingly. theres nothing you can do about it. the stock ecu will retard some timing when it picks up knocking.

to view the current knocking you either need an aftermarket ecu that supports it, a knock sensor reader kit, or apexi safc

[RBFIRE]

is there any syphtoms or signs to tell when knocking become dangerous? without geting either a PFC, knock sensor kit, or Apexi Safc?

will get pfc but in distant future, funds not allowed.

hope i wont kill my engine by then.

[paulr33]

if you can hear detonation or pinging then its bad, it sounds like shaking an empty can of spraypaint, but more of a tingy metallic sound. if you can hear it obviously back off, the cause of pinging/detonation is generally too much timing (or heat). if its repeatedly occuring try turning the boost down if its the stock ecu.

it does have the capacity to kill your engine or cause problems if left alone, however the stock ecu has "corrections" around the factory knock sensors (assuming they are working ok) which tell it to back off some timing (i presume) when it picks up certain levels

[rob82]

  paulr33 said:

if you can hear detonation or pinging then its bad, it sounds like shaking an empty can of spraypaint, but more of a tingy metallic sound. if you can hear it obviously back off, the cause of pinging/detonation is generally too much timing (or heat). if its repeatedly occuring try turning the boost down if its the stock ecu.

it does have the capacity to kill your engine or cause problems if left alone, however the stock ecu has "corrections" around the factory knock sensors (assuming they are working ok) which tell it to back off some timing (i presume) when it picks up certain levels

There are usually 2 ignition and 2 fuel maps for hi and low octane fuel for most Japanese Cars (Nissan, subaru, mistubishi and toyota). Knock sensors in early nissans are only active up to 4000 RPM under medium to high load(not sure on r34 and above). That means that if it senses too much engine noise in this map area it will then use the lower octane fuel and ignition maps. If it still senses too much engine noise it will not retard the timing above 4000rpm!!

If you can hear detonation through the firewall then it will be doing your engine damage. A good way to check for detonation is to have a look at your spark plugs and ckeck the insulator is not cracked, also you might see some pitting on the edges of the plug - this is more common.

Edited March 7, 2006 by rob82

[RBFIRE]

:)

will wind down the boost for a peace of mind!

cheers,

Edited March 7, 2006 by RBFIRE

[paulr33]

cheers thanks, was unaware it didnt use the knock sensors past 4000rpm

[blind_elk]

If you want to be sure, get some time on a dyno (half hour should be more than enough).

Do you have proper cold air feed for the K&N? This is the biggest risk to get knocking; the engine is hauling in hot air from the engine bay, and hot air is bad air for a turbo.

The ECU diagnosis only reports faults; unless there is an actual fault in the knock sensors, the ECU will report "all clear".

[RBFIRE]

yes, i have one of MR_crust Air BOX,

And going to dyno it this sat 11th, at the SAU UAS DYNO day, Cant Wait, 2 and a half days more to GO!!!

[RBFIRE]

thank you all, for the info.

[Scooby]

  paulr33 said:

cheers thanks, was unaware it didnt use the knock sensors past 4000rpm

anyone know why it's that way? seems strange to me unless there's a reason.

[croat]

  rob82 said:

Knock sensors in early nissans are only active up to 4000 RPM under medium to high load(

My R33 gtst knock sensor shows over 4000rpm. thats a load of shit

[Beer Baron]

  croat said:

My R33 gtst knock sensor shows over 4000rpm. thats a load of shit

the knock sensor is still reading noise of course, but i believe he's saying the ecu doesnt act on the knock sensor input above 4000rpm. i would imagine this may be because the sensor is receiving lots of engine noise above 4000rpm, but i'm only speculating, i've no idea if it's true or not.

[Blitz]

If you are using a factory ECU, any knock over 60 will trigger the check engine light if im not mistaken.

[paulr33]

no that is not correct. the powerfc is the only ecu i know of to make the engine light come on when knock > 60 level (adjustable level in datalogit).

what rob said is the stock ecu won't "consider" knocking levels over 4000rpm. the sensor still operate, just the ecu ignores them. the powerfc honours the knock sensors and display it on the hand controller at all times, regardless of rpm.

[rob82]

  croat said:

My R33 gtst knock sensor shows over 4000rpm. thats a load of shit

THe knock sensor is still active however the ECU disregards any noise it may pickup above 4000rpm. I believe that nissan turn it off at that rpm as there is too much engine noise above that point.

[MattSR]

Beer Baron and rob82 are correct.

The PowerFC still logs the knock sensor reading all the time however it doesnt use it for any form of active ignition timing control.

Cheers,

Matt

[RedDrifter]

  rob82 said:

THe knock sensor is still active however the ECU disregards any noise it may pickup above 4000rpm. I believe that nissan turn it off at that rpm as there is too much engine noise above that point.

Thats not quite true.

Though u are close.

I use the stock ecu and with conzult it will pick up any detonation. It will spit out a knock sensor fault(code 34) if knock goes past the set level. I have had it spit out the code well after 5k and it will pick it up well before you will hear it too.

It will still pick up knock well into the revs.

On the ecu's ignition maps the ecu has a knock(self learn) area but this area is where it will keep increasing timing till knock then back it off a bit(self learning area). And this area is in the lower part of the revs (4000rpm and less).