ChevyNo1

Just wondering . . . my PCM thinks my sensors are not working ( p0327/p0332 ) even though I've replaced both of them. I may be stuck tuning by ear until I get this figured out ( don't know what to do next ).

So if the car starts getting KR, can it be seen easily on a graph? Can you guys hear it on the dyno?

- Dug

jimmyblue

iTrader: (11)

You can hear pinging if it's bad enough. KR is supposed
to suppress it (what is the sound, of one hand clapping?)
and you would probably not see it if the dyno rolls up
slow; if the KR is applied evenly, it may in fact be holding
you at MBT and maximizing output. But KR is better at
maintaining steady-state operation at ping threshold
than it is at dealing with changing load conditions, its
time constant (on the go-away side) is pretty slow.

Ideally you would be running a logger during dyno pulls
to see what's what, and what wants tweaking. Here you
could get KR data.

ChevyNo1

Thanks . . . the only problem with trying to log it is my PCM think's they're fried, so no data . . . I had to turn them off in Edit or the PCM pulls 4 at WOT no matter what. So I'm tuning by ear . . .

Team ZR-1

Knock can be seen on a dyno if the PCM is reacting to it for timing would be effected and shows up in the graph as real wavy lines ( if smoother function of dyno software was not used)

ChevyNo1

Well, if my sensors are turned off then the PCM wouldn't really be 'reacting' to it, would it? Would it still show on the graph? I would think it still would . . .

jimmyblue

iTrader: (11)

Full time 4 degrees of KR sounds like the '98 model year
"we'll get it right later" knock sensor syndrome. Might
look into that, if you have never replaced the originals.

ChevyNo1

Yea, I have replaced them . . . didn't make any difference at all. I'm considering getting my PCM reflashed at the dealer ( never done it before ) and then putting my Edit changes back in manually. I'm at the end of my rope, I think I'm going to have to tune this thing by ear!!

- Dug

McRat

KR looks like step in the graph and it continues it's normal shape. Kinda like the printer skipped.

You WILL get more KR on the dyno than at the track from my experience. Allow 2 deg on the dyno, and you should be OK. 4 deg will show on the street slightly and intermittently.

McRat

PS - You can hear and feel real detonation. There will be no doubt in your mind something is wrong.

ChevyNo1

I've always thought I could feel it too . . . just want to make sure that it should be obvious . . . thanks!

GrannySShifting

iTrader: (10)

are you sure your getting continuity with teh knock sensors and they are plugged in? sometimes a bad tune will pop a knock sensor code, althoguh i never seen them pull much timing at all

ChevyNo1

Yep, we tested the pins on the PCM for the sensors and they return varying voltage when the heads are rapped . . . so we know they're in spec.

AZLS1

iTrader: (2)

If they are turned off you will not have any knock retard (you already knew that.)

So you will be seeing detonation on the graph which is easy to see. If your Dyno operator knows anything at all, he/she will be able to show you the detonation on the graph.

It will look like something like this in the area where the detonation is happening -> WVvVvWVWvWV

ChevyNo1

Thanks Sterling . . . yea, I chose the wrong words, I mean see detonation . . . thanks. Did you see my latest graph?