I am chasing rather significant Knock Retards. For example, I have made two test drives using the exact same SA table. Basically the same course. One drive had no knock counts and no KR. The other was full of them. For the most part, not under severe MAP load. I am thinking vibration, but still checking. May try to de-sensitize the KS.

But, in sorting the logs, I came across something I don't understand. I have the base timing on the ZZ502 set at 10 degrees. Both at the distributor and in the tune. When I sort the log on SA-TDC, the low end for a rather large number of samples is ten or so, meaning SA Ref is below the base of ten degrees.

What causes SA Ref to be driven below the pre-set amount

Mask 8$d

Don
Williamsburg

 

What do you mean by "or so"?

When I look up my base timing in the tune, it says 9.8 (even though I had entered 10).

For actual timing in the log, there are two timing columns.
SA (Rel REF)

SA (TDC Actual)

I think you have to look at the actual. The actual is the REF + your base timing. When I subtract Actual - REF, I get my base timing of 9.8 (as it appears in the tune).

 

SA Ref should equal (SA Tdc - base - knock retard). Knock retard will reduce SA Ref below SA Tdc - base.

I like to set my base timing to zero, so what you see (on SA Ref) is what you get. This also allows my distributor body to sit squarely which makes it easy to set and see if timing has slipped.

 

Here's an example of a CSV log. It's sorted on some column, but you can see the SA Ref dropping below the 9.8 degrees (set for 10 at the distributor). Corresponding, the SA TDC is dropped by the reduction in the SA-ref. Note that the car is locked and at highway speed.

Looking at the log, Tequila hit it. The drop in the SA Ref is consistent with a change in the Knock Counts. Not necessarily Knock Retards, but any change in Knock Counts drops the SA Ref and the SA TDC. I don't think it's detonation as the MAP and RPM are moderate.

Is there anything in the Tune that would desensitize the Knock Sensor?


.

 

Closer Look DFCO I think

 

Example log with base timing (initial advance) set to zero: https://datazap.me/u/tequilaboy/roll...4834-4704-4724

In this case, what you see is what you get (SA Ref).

The deviation between the SA Tdc and SA Ref is knock retard. SA Ref is not the base! It will be offset from tdc by the base and knock retard if present.

Note: Knock retard signal itself is improperly scaled (in the adx) in this data, so I chose not to display it here to avoid confusion.
2nd note: The Camaro (4th gen) couldn't keep up despite my being in the wrong gear for the situation (4+3 car with O/D active above the kick-down prevent rpm threshold-ha ha).

 

What has not yet been mentioned, is the range of SA that the distributor can handle. This is what is really going on here.

That is, the minimum SA, and the maximum SA parameters in the calibration. Which varies according to the actual distributor used (small cap, big cap, 6/8 cylinder, ...)

Which is independent of the at-crank SA (timing). A distributor can only handle so much advance, and only so much retard, without cross firing. So there are calibration parameters for this, that the ECM takes into account.

There are threads on this.

RBob.

 

2's complement of 0xFFF5 = 0x0B or 11 (really -11). 11*90/256 = 3.87. I believe this is the correct limit value for Max Spk Retard (Rel to Ref) and not 3.5 degrees as often commented. So the (decimal/integer) adjustment range is 130 (from -11 to 119) or 45.70 degrees (from -3.87 to 41.8 degrees).

If adjusting the base to zero, the limits should also be adjusted in order to maintain the same adjustment range. Therefore the range should be shifted by 5.98 degrees (or + 17) to 2.11-47.81 degrees (or 6 to 136) in order to account for the increased SA Ref. Hopefully my math is correct. Will give it a whirl.

Relevant original parameters from $32B:

LC01C: FCB 17 ; Spk Advance Ref, (5.9 Deg), (Val/2.844) ; Initial advance -- 6 deg
LC01D FDB $0077 ; 41.8 DEG Max S.A., (Rel to Ref.) ; (2's comp)
LC01F: FDB $FFF5 ; 3.5 3.87 Deg Max Spk.Retard (Rel to Ref.) ; (2's comp) (or -3.87 Deg Min SpkAdvance (Rel to Ref.))

Proposed new values:

LC01C: FCB 0 ; Spk Advance Ref, (0 Deg), (Val/2.844) ; Initial advance -- 0 deg
LC01D FDB $0088 ; 47.81 DEG Max S.A., (Rel to Ref.) ; (2's comp)
LC01F: FDB $0006 ; 2.11 Deg Min Spk.Advance (Rel to Ref.) ; (2's comp)

 

I am getting more confused by what I see in the log. The log shows that when I am at highway speed and drop the TPS below 0.8 percent, the SA drops by around 18% below the SA Chart.. That doesn't jive with my Spark Advance Closed Throttle vs RPM Table. I have that table set at Idle SA (23.2*) and 16.88* above idle RPM. What I expected at highway speed was when you let of the accelerator (TPS below 0.8), the SA would drop to 16.88 degrees. Not what I am seeing. It seems more line the SA is dropping the 16.88 degrees below the SA Table.

For example: ,sample 7869 TPS = 1.2% SA is per the SA table at 30.59 degrees. Sample 7870 TPS = .8 and SA is 11.95 Degrees. RPM and MAP basically the same.
Don
Williamsburg

 

SA is calculated based on different parameters in $8D:

SA Main Table
+/-SA CT correction
+/-SA-PE
+/-SA-HWY
+/-EGR (??)
+/-SA Start-up

SA-Closed TPS
+/-SA Start-up
+/-SA Idle RPM error
+/-DE
+/-Stall Saver

DFCO

Knock Retard
Low Octane Knock Routine

UPDATE: Hot restart SA adder

 

Deleted

 

See my post #10

Looks like you are decelerating after letting go of gas pedal, so you are entering DECEL followed by DFCO. Your log doesn't show INJ BPW, so no way to know. If you have low BPW, you are in DECEL, if INJ BPW is 0 msec, you are in DFCO.

 

Deleted

 

SA Main Table
+/-SA CT correction -- Not sure what this is?
+/-SA-PE - Not in PE
+/-SA-HWY Not in HWY (disabled)
+/-EGR (??) No EGR
+/-SA Start-up_ Cruising, ten minutes into the log

SA-Closed TPS
+/-SA Start-up Cruising ten minutes into the log
+/-SA Idle RPM error _ I thought this was only applicable if in true idle (speed = zero)
+/-DE Not sure what this is
+/-Stall Saver

DFCO Not is DFCO

Knock Retard No KRs shown at this point in log, however there seems to be an association between the drastic drops in SA when TPS drops below 0.8% at cruise speed (below the DFCO speed threshold). Usually upon resumption of TPS position above 1.8%.

Low Octane Knock Routine

Cruising 45 MPH, drop the TPS below 0.8% and the SA drops to 12 degrees even though the chart "Spark Advance-Closed Throttle vs RPM" is set at 16.88 degrees. Why does this Chart not limit the SA to a minimum of 16.88 degrees?

Don

 

With hidden columns visible on BPW.

Not in DFCO. If in DECEL, do that change the SA?

 

You are in DE (Deceleration Enleanement), it pulls around 5 degs. That is based on my multiple data logs I have done over the years. I don't know why but it does. You can datalog DE status, so you'll know. Basically, closed TPS SA - DE SA correction

 

+/-SA CT correction -- Not sure what this is?
0x13B Table SPARK ADV, Temp. Correction .vs. Load .vs. Coolant Temp.

+/-SA Idle RPM error _ I thought this was only applicable if in true idle (speed = zero)
Depends what you have set up in your tune. 0x495 Idle Max speed, usually around 15mph

You can datalog Idle Mode status

 

Hope you are using S_AUJP!!!!

 

Thanks for the information. I checked that same log for events where Decel was in play. If Decel was activated and TPS was above 0.8 percent, there seems to be no impact on SA. If TPS was below 0.8 percent, then SA dropped to the low 12 degree level.

Using S_AUJP_T v7-11.XDF

 

You're welcome.
Yes and no. I have logs where it pulls timing in DE even if not in Closed TPS SA and sometimes it does not. As long as you are aware of it.

 

slightly different subject. I do not know what I did or how to get back but I went from the small chart font to the behemoth font and cannot find my way back. See attachments

 

I am reverting back to the basis of my Original Question(s), as I have not found the answer in the logs from the suggestions in this thread.

If I am at 40-50 mph and drop the TPS below 0.8 percent, the SA drops from the Table Value (around 28-30*) to 12 degrees plus or minus a bit. Base is set at 9.8 degrees. That is a drop in SA of about 16-18 degrees. The Closed Throttle SA table is set at 16.88 degrees at all RPMs over 1000 (below 1000, set at idle SA)

I am not in DFCO
Although occasionally I am in Decel, it is not consistent with the drop of 16-18 degrees when I go to TPS below 0.8% at speeds of 40ish mph. I have looked but cannot find any parameter linking Decel to a change in SA.
There are a few KR, but they seem to be when TPS increases after an event of low TPS. The KRs don't appear to be associated with the initial drop in SA



It is as if the Closed Throttle SA vs RPM table is dictating the "drop" in SA not the "floor" when in in a closed throttle position.

Why does it not drop only to 16.88 degrees per the table? Other than DFCO and Decel, what else could be happening.

See Monitor attached for example. All the wild stuff with SA on the right side (I believe) is related to RPM at the threshold between OL and CL (Open loop idle below 1000 rpm)

 

Maybe I was not clear enough earlier. My bad.

I have the same patterns and could never explain them. Pattern goes like this (manual car):

A)Cruising at 60mph = SA Main table + CT correction = it adds up
B)While cruising at 60 mph, release gas pedal, stay in gear, TPS goes to zero or near zero, but VS is 60mph going down, DE activated for around 1 sec, no idle mode = Exit SA Main table, enter closed TPS SA table = Difference of around -4*, it does not add-up
C) While decelerating from 60 mph after DE, entering DFCO = SA goes to base 12* and ignores closed TPS SA table

Sometimes if decelerating (A&B) without entering DFCO (C) or delay between DE and DFCO, SA will be off by around -4* from closed TPS SA Table. Also, if coasting in neutral at low speed, entering idle mode, no DE, no DFCO, SA will be off by around -4* from closed TPS SA Table.

Could NEVER explain it.

I have a way of tracking it after the exported data is entered into my Excel database/calculator. The database has functions to calculate SA and flags differences between calculated SA and reported SA (like you do manually). The database will tell me when the above conditions are met so I can ignore discrepancies.

I would no worry about it.

 

... basically if you have speed and closed TPS, SA is off by around -4*,except in idle mode when it'll be +4* to -8* depending on your tune

 

One more unexplained event.

TPS at zero. Coasting down to a stop. When RPM gets near idle RPM, the SA begins to cycle up and down as if in "idle" It almost appears the tables for Idle error advance and retard are kicking in. Yet the car is moving as shown by the VSS.

Again 8$D, aren't the tables "Idle Spark Advance vs RPM Error" and "Idle Spark Retard vs RPM error" limited to pure idle (TPS near zero and MPH zero?? If so, what could cause that variation

See Monitor

 

Told you before (post #17) that idle mode is entered before you reach 0mph!!! It depends on your tune. That's why it can cycle up and down. Basic AUJP v 7.0 is set at under 15 mph. Check for idle mode on when data logging

 

Everything you are describing is perfectly normal with $8D.

 

Bear with me, just trying to learn this stuff

I found these. It appears to state that Commanded Idle can be implemented at MPH below 20 MPH. The second one would indicate that Commanded Idle would be increased by 100 rpm if moving. My commanded idle is 900 rpm, bumping Commanded idle to 1000 if moving. And, if MPH is below 20, then the advance/retard correction factors would/could be implemented.

Yes?

 

If vehicle is moving in neutral, rpm will always be higher than commended idle. It takes a few seconds after stopping for idle to settle. Again all normal, not saying I can explain exactly why it's doing it, but it is.

Yes and no

"RPM Added to Commanded Idle if Moving" is supposed to add RPM to idle when moving. However when I zeroed it out it did not change anything. Idle is still higher when moving in neutral.
"IAC PID Battery Param, No Change to Commanded Idle RPM if MPH >" has nothing to do with it. It's part of a routine to adjust commended idle RPM if voltage goes too low.

I believe what you are refereeing to is:
IAC PID Enable Param, Considered Closed Throttle if <= (0x647) = 0.78%
IAC PID Enable Param, Considered Moving if > (0x649) = 0.9mph

I am referring to:

* CLOSED LOOP FUEL CNT'L PARAMS & TABLES
*****************************************
L8494: FCB 6 ; 2.3% TPS MAX FOR IDLE
L8495: FCB 48 ; 15 MPH MAX SPD FOR IDLE

Loop Closed Param, NOT in Low TPS & MPH State if MPH > (0x494) = 15mph
Loop Closed Param, NOT in Low TPS & MPH state if TPS% > (0x495) = 2.3%

That is your idle mode

 

Found them, thanks Merry Christmas