I just got my car running since I put the new motor in, and it has no knock and yet 5 degrees of knock retardation at idle. I was just wondering what in the ECM controls this.

 

There are tables with the eprom that you can control the "Attack Rate" (the speed at which the ecm pulls timing out), the "Recovery Rate" (the rate the ECM lets the Retard decay/let's the ECM go back to full timing), and "MAX Retard" for WOT vs RPM and Kpa vs RPM (MAP).

When the Knock Sensor is detecting "noise" of the frequency of the KS, it sends the signal to the ECM and the eprom then starts to pull timing until the noise goes away (or it hit's the retard limits).

That's the simple version. In reality, it is far more complex.

 

Well that helps some. Another question for you: If Code 43 is stored, will the ECM pull out timing even though the KS is not detecting knock. Thats what my Auto X Ray said it was doing. If anybody has Auto X Ray, they can see what I'm talking about.

 

If you have a code 43, then the eprom may very well run off "pre-set" values in the eporm (Safe Mode). Clear the Code 43. If the Code 43 returns, then you have to address that.

 

I just went driving around, and after 5-10 minutes of driving, the SES light went out, and it drove normal. I had the dist. base timing set at 3 degrees BTDC to be on the safe side. It felt it could use a little more timing though. I'll try 4 degrees tomorrow.

 

I might add that if you are getting knock counts at idle you may have something else wrong.... Such as incorrect scantool results, improperly tightened knock sensor, or some sort of loose component making 'noise' that the KS is picking up (ie false knock)... But if all you get is 5 counts and it stops logging counts after that, the sensor might just be picking up 'noise' from the starter or something when it first starts up. Base timing should be set at 6* for a stock engine and PROM combo..... And, as Glenn stated, if you have any kind of DTC stored, it will need to be addressed before any kind of tuning is performed.

Hope that helps some,
Good Luck!
Matt

 

That is not clearing the SES code. The ECM just stopped reporting it, but it is most probably still in the ECM.

 

The ECM always does a test of the KS when first started and will always report SOME knock counts (should be less than 10) when first started and then stop. This is normal.

 

That sounds logical...But, what does the ESC module do???