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What are the most important parameters to monitor with the accessport while driving?

OVRKILL

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I'm glad somebody finally asked this question. I've been searching and could only find Subaru guys talk about knock sensors and the octane adjust ratio. Wish somebody could explain how to interpret the different knock sensors. I've read conflicting opinions on the subject whether or not one instance of knock is to be expected or blah blah. If somebody could chime in that'd be cool.
As I understand it, it's not entirely critical as long as it's in the right context.

The sensors are very, well, sensitive, and any blip whether it's LSPI, a tiny knock, or full-on detonation, will all come up the same on that counter.

Under throttle, the ECU will gradually advance timing as RPM increases. If there's a little bit of knock from too much timing, the engine will see that count and pull some out. The knock should stop there. On a well set-up car there will be only one count or two at most. If your car keeps knocking, for more than three counts or so, or goes into negative timing at the same time, you have a real problem.

here's a graph of a minor knock event from a pull I made yesterday:
http://i.imgur.com/WHDUmZw.png

If the knock had been more severe, the knock count would continue to increment and the ign correction would pull almost all the way out. This wouldn't matter with preignition, which is why LSPI is so deadly.
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Kjewer1

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I think when it comes to all of the knock parameters, the best place to start is probably to trust the ECU programming. OAR is the long term running trim based on all of the knock feedback mechanisms and programming, so that's the only one I watch on a regular basis. You'll want to look at specific knock events and individual cylinder conditions when tuning certain things, but not on a regular basis. IMO, let the ECU do its job. This all assumes OAR hasn't been rendered ineffective by poor tuning practices.
 

acull2000

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This graph is very helpful, so thanks for that first of all.

To plot knock on cyl #2 what signal have you logged? I have knock sensor 1 and knock sensor 2, is there some processing of this required, or have I completely missed a signal?

As I understand it, it's not entirely critical as long as it's in the right context.

The sensors are very, well, sensitive, and any blip whether it's LSPI, a tiny knock, or full-on detonation, will all come up the same on that counter.

Under throttle, the ECU will gradually advance timing as RPM increases. If there's a little bit of knock from too much timing, the engine will see that count and pull some out. The knock should stop there. On a well set-up car there will be only one count or two at most. If your car keeps knocking, for more than three counts or so, or goes into negative timing at the same time, you have a real problem.

here's a graph of a minor knock event from a pull I made yesterday:
http://i.imgur.com/WHDUmZw.png

If the knock had been more severe, the knock count would continue to increment and the ign correction would pull almost all the way out. This wouldn't matter with preignition, which is why LSPI is so deadly.
 

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acull2000

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Thanks [MENTION=20641]BoostedCanadianPoney[/MENTION] - not sure if this has been posted before but it's a great article, well written.

I realised I was logging the knock detector reading itself, not the cylinder knock count.

If I had to guess, the two knock detectors manage to listen to all 4 cylinders, and the raw values (can be monitored under knock sensor #1 and knock sensor #2) are processed by the PCM which outputs the cylinder knock count.

All clever stuff, I'm learning :cheers:


 

PRG3k

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I use 4 of my 6 for the ignition timing correction on all cylinders. It can be a good indicator of somethings not right. Like I figured out my oil level was slightly overfilled once because of that.
How?
 

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apx632

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I run the following 6

Air/Fuel Ratio
Boost Gauge
Ignition Correction Cylinder 1
Ignition Correction Cylinder 3
OAR (Octane Adjustment Ratio)
Charge Temps

I may swap out the boost gauge for another Ignition correction as the AP and the boost gauge in the car read the same.
 

Wulf Titan

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My OAR always drops below -1 and I have frequent negative cyl correction with my Tune+ config. Surprised my car hasn't boomed yet.
 

stevnoof

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Probably because the tune/ecu is doing its job and pulling timing. Talk to Adam he will adjust it for ya.
 

MakStang

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I have two alternative setups on my Accessport.

I either monitor the following parameters:

Charge Air Temps
OAR
IGN CORRECTION 1
IGN CORRECTION 2
IGN CORRECTION 3
IGN CORRECTION 4

Or, alternatively, I monitor the following:

Charge Air Temps
OAR
Estimated Torque
IGN CORRECTION 2
IGN CORRECTION 3
IGN CORRECTION 4
 

Jake

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Engine:

[ ] Blown up
[X] Not blown up

If that changes, you're going to want to do something about it asap.
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