Knock With Pfc

[bish33]

hey all recently had a pfc installed in my 33 gtst, now wen my car is at full boost and usually around 6200rpm the engine light will flash on and off which i kno is the power fc sensing a knock over 60, it doesnt always do it tho. I took it back to the tuner and he said that he has done a real safe tune (191rwkw) and did a couple more power runs to make sure, and sed coz my car has done round the 170,oookm that is prob just something elses knockin/loose in engine and engine is not at detenation. oh and i hav seen the knock go over 100. Car mods: pfc, fmic, 3.5cat back, walbro pump, pod filter, platnium plugs. Any help would be appreciated cheers jarad

[paulr33]

read the PFC FAQ in my sig - it tells you how to fix knocking etc

it will knock differently on the street, it happens to every tune

the dyno is great, but the street load is every so slightly different

either take the tuner for a trash on the street and make him fix it while he is in the car

or speak to another tuner and ask for the same thing or learn how to fix it yourself (its easy)

the faq will help you

[tridentt150v]

But first you have to find out if it is knock or noise??? [i'm going through this atm]

[bnr#@]

Would like to know this to, trying to figure out where my high knock readings are coming from... get it up into the 100's

[tridentt150v]

You, like me need someone to use a Gizzmo k-mon or some such......do a search on the gizzmo and have a read.

[paulr33]

it will be knock

i guarantee it

almost every time

1) guy goes to get ECU tuned

2) tuner tunes on dyno and sorts out the tune.

good power. good AFR's. no knocking nice and safc

3) owner trashes it on the street

4) it knocks

its becuase the load axis it touches are ever so slightly different

than to how the dyno simualtes it

also be sure to note the owner ALWAYS trashes the flamin mongrel out of it differentlyt

to how the tuner plonks it on the dyno etc

if it was me, and it was my workshop part of the tuner would an on-road tune

sure it might add more cost, but it would cut out the knocking on street problems we see

[bnr#@]

Mine is something else other then the tune as I can take 5 deg timing out of the map all round and still get the exact same knock readings

[bish33]

wher bouts are the knock microphone's located on the block? would like to see if ther is anything loose that could cause the knock reading. My car seems to not to bad on smooths roads like sometimes i wont get knock at all but wen i go over bumps boosting thats wen i seem to get high knock reading

[jay1]

will be knock

[zebra]

if you have a slight miss it will register as knock on the pfc, happens to me all the time, spark breaks down and knock levels go through the roof.

[45ULT]

mine just started having massive readings even when free reving the engine, it would flicker over a 100. even on base map with stock rb25. u can't tell me its knocking. also is there any way of updating the software on the actual power fc unit?

[bish33]

if you have a slight miss it will register as knock on the pfc, happens to me all the time, spark breaks down and knock levels go through the roof.

Well thats interesting to kno, that could well be the cause of my knock readings goin so high

[Sheng]

i thought 150 was bad

[bnr#@]

Im still chasing mine, knock levels dont go down even when i lift of the throttle, just hover there until revs drop. Also sometimes its all good and the knock level is fine so its an intermitent thing... Ideas? Knock sensors themselves are new btw

[Bennett]

If your not on throttle then it cant be knock

[bnr#@]

If your not on throttle then it cant be knock

Thats pretty much my thoughts, but what can it be?

[Guilt-Toy]

for $150, i will use a Gizzmo Knock Monitor on your car and do a few runs on the dyno and send you some graph's of the the real noise your engine is making.

A screen shot something like this,

Then you know that your engine is running fine. The only way to get a decent tune from your engine is to turn the knock sensors off and tune it with torque read outs. Tuning a engine with a k-mon monitoring knock and not the power fc knock sensors allways see's extra power.

In my car i was making 30kw more on the same boost levels because I was getting knock spikes of 80 with the pfc knock sensors and only 35 with the K-MON.

Sad to say, but 70% of you guys are running around on de-tuned engines.

[Bennett]

I read a short while ago about some guy who's oil filter relocation kit i think it was, was vibrating against the chassis and it was vibrating at the same frequency that the knock sensor is designed to detect. So something in your engine bay could be loose causing the knock sensor to jump only in a certain rev range.

Is your car missfiring? I went through a stage of extremely bad missfire and knock would reach over 100.

Otherwise could just be engine noise but if its a quick spike to over 100 then i doubt it very much.

[bnr#@]

Mine is almost always between the 2500 to 3000rpm range, and 70 to 80 knock is common to see 100 sometimes

[barnoon]

Ive had these constant knock issues ever since I got a PFC back in 06, NEVER knocks on the dyno, take it on street knocks all the time around 6k, take it back to tuner they throw it on dyno say nothings wrong, take them for a drive and show them, they blame it on my pod sucking too much hot air. So I then put a stock airbox on with a cold air feed, still friggin knocks.

Went to a new tuner and got a new tune, again same problem, no knock on dyno knocking on street, he made some adjsutments, still knocks.

Went to a 3rd tuner, STILL SAME PROBLEM. Ive never had a knock free car for almost 3 years now and it shits me like crazy.

Im thinking of takin my bigger tturbo / injectors etc off and just going back to a stock ecu its annoying me that much.

If anyone on here from Sydney can GUARENTEE they can make my car knock free with a road tune, PM me and ill give you some business.

Edited November 26, 2008 by Dave69001