Spark Tables vs Datalog SA

Hi All, I'm hoping someone can help me with this question or point me in the right direction. There seems to be a disconnect between what I set my SA to in the main spark table and what I'm actually data logging. I've looked at some of the modifier tables and they all seem to be adding spark. But for some reason I'm seeing close to 10's less spark in the data log than I have in my tables. Is this a data log issue or is something else lowering the SA?

Thanks for any help or suggestions.

10 degrees is about what most old gm calibrations subtract for a knock sensor failure. do you have a knock sensor failure?

failing that it must be an ADX issue or something

Quote:

---

Originally Posted by steveo

10 degrees is about what most old gm calibrations subtract for a knock sensor failure. do you have a knock sensor failure?

failing that it must be an ADX issue or something

---

Not that I'm aware of. It's a band new sensor, I'm not getting any codes and I get occasional Knock detected. I do have all the EGR stuff turned off for purposes of data logging not sure if that could affect it.

Does the logged advance match a timing light? Is it times at zero without computer control timing?

Quote:

---

Originally Posted by IamBrad

Not that I'm aware of. It's a band new sensor, I'm not getting any codes and I get occasional Knock detected. I do have all the EGR stuff turned off for purposes of data logging not sure if that could affect it.

---

for the hell of it run the factory cal to see if you broke something

Quote:

---

Originally Posted by ralmo94

Does the logged advance match a timing light? Is it times at zero without computer control timing?

---

It's pretty close up to 10's which is as high as the markings go on timing marker.

Quote:

---

Originally Posted by steveo

for the hell of it run the factory cal to see if you broke something

---

It does not like the factory cal much now that it's got the new cam and heads. I'm thinking it might be the "Main Spark Bias" or "Coolant spark Bias" which are both set to 9.8'. When I have some more time to mess with it I might try and set those to 0 and see if that makes a difference.

If I remember correctly the bias is a computation from other adders and if you zero them they won't compute. When I tried setting them to zero it didn't work for me. I'd look at altitude and octane retard. I think that's what they were called in $OD

Quote:

---

Originally Posted by ralmo94

If I remember correctly the bias is a computation from other adders and if you zero them they won't compute. When I tried setting them to zero it didn't work for me. I'd look at altitude and octane retard. I think that's what they were called in $OD

---

I did some more playing with it and it seems to have something to do with turning off the EGR etc for Datalogging. When I run the normal tune with the same VE and Spark tables it seems to come out a lot closer to what the main spark table is supposed to be. I tried to set the EGR spark bias to 0 but that still did not seem to make much of a difference.

is this for tbi/tpi? if so have you verified your initial timing is set the same as what is in the calibration?

Quote:

---

Originally Posted by tayto

is this for tbi/tpi? if so have you verified your initial timing is set the same as what is in the calibration?

---

It's a TBI and yes, the initial timing is correct. It seems to have something to do with when I disable the EGR functionality to data log. I'm just not sure what setting is causing the timing to be off when the EGR is disabled.

how are you disabling egr?

Quote:

---

Originally Posted by tayto

how are you disabling egr?

---

I used the method laid out in the XDF file