Knock Sensor Spiking On Pfc

[Suspense]

When changing gears i get a KNock spike on my PFC of about 60~80 sometimes...

Is this spike in between gear changes normal, or is something wrong?

[BHDave]

Are you letting the revs bounce off the limiter at all (~7k gear change)?

Does it do it if you short shift at say 6-6.5k?

[Cubes]

As you come off the throttle it uses load points that have most probably not been tuned, as a result slightly detonating.

This is very hard to replicate on the dyno, one good reason the car must be taken for a street run to ensure everything is a.o.k.

One easy fix is to rip out 5degree's. If it does it thenyou know she's running a little too much ign. timing in the cells above the cells that wot uses.

Edited January 7, 2006 by Cubes

[paulr33]

as cubes said when you back off the throttle and clutch in theres a brief moment where the airflow meter "load" will drop but revs will at the same range so youll be in cell area say 15 across ish and 4 or 5 down which wont be tuned. a map trace would easily show you which cells and then you could just take out a few degrees there

[Suspense]

as cubes said when you back off the throttle and clutch in theres a brief moment where the airflow meter "load" will drop but revs will at the same range so youll be in cell area say 15 across ish and 4 or 5 down which wont be tuned. a map trace would easily show you which cells and then you could just take out a few degrees there

<{POST_SNAPBACK}>

No i am not hitting rev limiter, and it is slightly rectified when i quick shift, yes.

So obviously my tuner hasnt done a proper job? He should fix this free of charge? i just got the PFC n tune on friday...

[Cubes]

As I said earlier.. its pretty hard to get it spot on unless you take it for a good road test, which many tuners don't. Even then under some rare circumstances such as brisk hills driving you may find your self using a load point that isn't usually used as a result it may have a slightly higher detonation reading.

Its hard to get it spot on. Takes time and tweaking.

[Suspense]

As I said earlier.. its pretty hard to get it spot on unless you take it for a good road test, which many tuners don't. Even then under some rare circumstances such as brisk hills driving you may find your self using a load point that isn't usually used as a result it may have a slightly higher detonation reading.

Its hard to get it spot on. Takes time and tweaking.

<{POST_SNAPBACK}>

Fair enough, we took it for a road test though with the laptop connected doing a map trace, no green highlighted sections... at one stage knock went up to 88 (not while tuning this was last night)

Edited January 8, 2006 by Suspense

[Sydneykid]

When changing gears i get a KNock spike on my PFC of about 60~80 sometimes...

Is this spike in between gear changes normal, or is something wrong?

<{POST_SNAPBACK}>

Knock with throttle closed is irrelevant, no engine damage possible. Move on.

cheers

[Cubes]

and it is slightly rectified when i quick shift, yes.

<{POST_SNAPBACK}>

Most off us roll off the throttle quickly, we don't simply jump off it having it completely closed within a couple ms, I had to drop 2 degree's from the 2 load points above the load points used at WOT, around 3000-3500rpm from memory.

If I were to change and slap the gears quick i would not experience high knock readings. At first I suspected fuel injectors but it wasn't.

Edited January 8, 2006 by Cubes

[drifterx]

take back to tuner if u unhappy, my knock went to 120 when i broke my gear box. or ur engine is getting old

[neo32]

hey got a queston simlair topic any replies appricates with my power fc when running down through the gear ie engin breaking i get quite high knock ratings ie 40 withc is much highte then even when ime on it hard i get readings of like 15 thanks guys for your replys