jef57

hI

MY PFC READ 143 KNOCK (max), 0.9 bar ( 5 gear)

I running with octane 100

everything is ok?

Gorilla RE

iTrader: (1)

NO! but your knock sensor is prob just bad. check your sensor and see what kind of condition its in, if its good then YES you have another issue. i dont see knock above 20-30 under boost...if that!

jef57

MY PFC FLASH HWL (exhaust temperature sensor) on commander

HOW COULD IT BE BAD ?

KNOCK SENSOR LOCALISATION?

thanks

jef57

pfc base map (fd3S4)

alexdimen

iTrader: (13)

The knock sensor is located on the left side of the engine block above the spark plugs. Download a copy of the workshop manual.

clayne

At idle in my garage.

clayne

One thing I will say is that KS readings are typically bogus and/or inaccurate. But I'll also say this, in the OPs case, 0.9 bar in 5th gear means a steady hard pull - the type of situation I would be most likely to trust knock sensor output.

Gorilla RE

iTrader: (1)

Engine braces, solid motor mounts, trans braces and diff braces can and do cause inaccurate knock readings. If you have none of these then it is most likely a bad sensor.

rynberg

What does it read at idle and steady-state cruise? What does it read at lower boost continuous throttle?

I would be very worried. 0.9 bar on the Commander is more like 1 bar in reality.....14 psi on stock fuel system and PFC base map is NOT a good idea.

jef57

idle knock is 0 - 20
Cruise 60- 100

O.87 WOT
O.9 WOT 5 GEAR

so i need to tune my pfc
and about fuel pump?

batmuk

id do the 12volt mod to the fuel pump man.
then get a wide band o2 into it.

and also a fc datalogit.

SPICcnmGT

^you don't need to do anything to the fuel pump until you figure out why it is knocking so high. 60-100 for cuise is odd.

Not having a WB 02 and datalogit, I personally would start by adding fuel to the PIM voltage/rpms and try that. If that doesn't do anything then I would try taking some timing out, or maybe do both at the same time. Probably want to try the cruise area first, and go WOT until you figure it out. If you can find someone near by that is knowledgable that would be your best bet.

Is it that high all the time, or does it just go that high when you let off and it backfires??

rynberg

Your sensor is bad/loose or you have something else making drivetrain noise if you are getting idle/cruise readings that high.

Gorilla RE

iTrader: (1)

IMO a knock reading of a over 100 while using 100 octane fuel during cruising is more likely to be something else i.e. bad sensor or to much engine noise (as i stated before). i am in no way saying that it is not a fuel or timing map issue because it very well could be. but i would look into those thing first and DONT drive hard or much at all for that matter. also i have to say, even if youre not going to tune your car yourself i still highly recommend getting a WB just so you can monitor it.

-J

Gorilla RE

iTrader: (1)

ha damn i walked away from the computer while typing and you beat me to it.
-J

jef57

Pfc Timing Going WRONG With Hks Twin Power?
So High Knock?

SPICcnmGT

I agree it is probably bad, I'm trying to state possible safe ways to test it some. I would say 100 with a backfire is not to bad, but 100 cruising is.

SPICcnmGT

HKS will not effect timing.

jef57

Since power fc base map run rich my car with my mods,

it seems to be a bad sensor, strange because my car only have 25 000 Miles...

Gorilla RE

iTrader: (1)

I've got a "new" bad sensor from mazda....rare but it can happen. besides its time not milage.

rynberg

I don't know why you keep saying that because it is not really true and you are pushing the limits of how much boost to run on stock fuel system. I told you in your other thread(s) that you should lower your boost level.

The knock sensor is just a microphone, they can go bad over time.

clayne

Knock sensor output is meant to be taken relative to it's normal level of noise.

A hard pull with a huge spike out of the blue with nothing else going on (i.e. not shifting, not slamming into road inconsistencies, etc.) is most likely something actual and not an error.

tdazmansFD

iTrader: (1)

When I first got my car back from getting a Rebuild, I had a used PFC installed with a safe tune with the commander, for break in only.
I noticed my knock readings would spike near 200 with light engine revs(4k maybe) and on Decelleration.
Even at idle it was reading knock of 20-30. It would increase as the RPM's increased slowly too.
After my 1000 miles, I had the car Tuned by Steve Kan. Nothing changed. Except in runs like an Animal!! lol

This is with fresh 91 Octane.

I did some searching on the forum for acceptable knock levels, and it seems that many people have the same problem as I do and have never figured it out completely. Even after replacing with a new KS. And they have been running around on these readings for thousands of miles with no issues at all.

9Sec7

the wire that goes to the knock sensor is very sensitive which is why it wont read right

RotaryEvolution

iTrader: (30)

i tend to ignore the OEM knock sensor, if you are worried then pick up a real knock sensing device.