PFC Knock readings
 

What would you say are normal reading on the POWER FC Knock sensor

My car has been tuned and raced for the past 6 years without any faults or engine rebuilts.

What I am trying to say is that if there was a problem with knock the engine would have died a long time ago.

So back on topic , I get between 85 and 105 on the PFC Knock meter. Is this right? If not could it be a faulty knock sensor?

Thanks alot

This has been covered many times in the PFC forum.

Cliffs Notes: non boost knock readings are irrelevant, cars vary considerably in their average knock levels

try it with new spark plugs

that seems high to me because my max knock reading is never above 40, and under boost its usually always below 20, it is when you let off the gas that you get the high spikes which show up as your max knock. but lots of others have reported the same as you. do some datalogging and see what exactly the knock is doing and when it spikes that high.

Best thing to do is look at the actual chart and see the pattern so that everything is in context. If you have a Datalogit post some logs.

all cars are different, for example, when my FD had stock clutch/flywheel and motor mounts knock was never over 40

fast forward to urethane mounts, ACT street/strip and prolite flywheel and it always goes to 85 or so around 3000rpms with or without boost.

I have a very stiff setup with a HKS Twin plate clutch without springs. Before that an EXEDY double plate as well.

The car has given me the same results with both new plugs and old plugs . I recently redid my wirring loom and made sure all was in place ( knock sensor , wirring etc )

Anyways there doesnt seem to be a straight forward answer so since the car is running fine I will leave it alone

Thanks

High knock in vacuum is usually noise. Full throttle under full boost it usually comes down.

thewird

"there doesnt seem to be a straight forward answer"

i mean no dis-respect but you haven't give enough info to get a proper answer.

ideally it would be good to have a chart w knock and PIM. if that is not available at least tell us where the knock is in relation to load and RPM...

as you say, your motor is motoring so probably you are O K. if i had knock in boost around
80+ i would be looking for answers. (check the plugs for signs of knock)

knock above 15 psi should be not much higher than 40. my knock in boost drops to below 10.

howard

Dear Howard

I am not being dis-respectfull either but have you tried accelerating in 3rd or 4rth gear while doing ie 125-140mph on the raod and at the same time looking over your commander to see under which load or rpm it happens??

Personally I would prefer to keep my eyes on the road. I am not a tuner or ECU programmer. The car has been professionally tuned several years ago and it has been working fine ever since

I dont have any data loging at hand. All I can see is the max values printed on the commander after ie one hard pull through all gears.

So to clarify things , my peak or max value of knock has been 85-100 but I cannot comment on which rpm. All I can say is that boost is in the area of 20-22 psi


I also send you a pm asking a few things about methanol/water injection. Have a look and reply if you can

On your commander in the monitor screen you can hit the next button once or twice and then you will have a graph/logging view, so do a pull and then if you hit the left button I think it will freeze the graph. So then you can see what the knock looks like, that might help. Or of course buy datalogit

Mine :
Idle to 4000 RPM in neutral : 60 to 160
on boost : 0
"mild" street port, single, lightweight flywheel, ACT unsprung clutch, no flexi pipe on exhaust, ... Noisy engine, for sure.
If it can gives you an idea of how high it can be at idle.