New Tuning Tutorial: WeathermanShawn

[y2k2z28]

Shawn,

I am not high and dry, I am still playing with it a little, trying to see if there are capatible PID's for the E38. Then I will change the calc PID's and see what happens. You never know it might work.

If nothing else I have learned a ton about the program and how to change different this.

[5.7ute]

One thing I believe people should be aware of, is that B0120 isnt an absolute switchpoint between a predicted & measured cylinder airmass. With increasing rpm, B0120 is where the pcm transfers from Speed density(predicted) to maf (measured). However, once enabled the rpm has to drop x rpm below B0120 to return to the predicted airmass tables. In the Holden OS 12202088 & 12220574 this value is set at 100rpm.
So when filtering the data, it may be wise to exclude this rpm band.

[WeathermanShawn]

Good point.

One thing I have been working on, is whether B4107 is controlling when MAF is enabled (just like B5913).

If that is the case (big if), then B4106 the LTFT Update Filter will be totally controlled by MAF.

If that is the case, then any Airflow correction is being ignored by MAF unless it exceeds the amount dictated in C2911 (MAF Rationality Test).

At this point, I have no way of proving it. Except for the fact that you can load up a lot of bogus VE Tables B0101, and the effects on Trims seems very negligible.

While I know there is a lot more to tuning..it really makes you wonder if anybody really knows the exact MAF/VE blending. How much of the VE Table is 'just in case of MAF failure.???

Proving this is the challenge!

[TAQuickness]

One thing I believe people should be aware of, is that B0120 isnt an absolute switchpoint between a predicted & measured cylinder airmass. With increasing rpm, B0120 is where the pcm transfers from Speed density(predicted) to maf (measured). However, once enabled the rpm has to drop x rpm below B0120 to return to the predicted airmass tables. In the Holden OS 12202088 & 12220574 this value is set at 100rpm.
So when filtering the data, it may be wise to exclude this rpm band.

The PCM doesn't measure anything. It looks up the air mass data from a table respective of the input signals. Both cases, VE and MAF, would be better described as predicted or interpolated.

[5.7ute]

B4107???
The LTFT will be stored in a seperate part of the pcm & added to the final Airmass?/fuelmass? (not sure which but it will work out the same). So it wont matter what model it is using at the time, Sd or maf.

[5.7ute]

The PCM doesn't measure anything. It looks up the air mass data from a table respective of the input signals. Both cases, VE and MAF, would be better described as predicted or interpolated.

I agree. It is just that the maf measures the airflow, where SD is a predicted best guess. I find it easier to comprehend when using this terminology.

[WeathermanShawn]

Its just something to think about (B4107).

I did not start thinking about it until I did two separate logs..one where I added +15% to the VE Table, and another where I subtracted -15% from the VE Table..(still keeping MAF Enabled-Closed-Loop).

The LTFT Trims were so identical, that I started hypothesizing that just like cylinder air (when MAF enabled) dictates spark, perhaps when MAF is enabled it also dictates Trims. I mean 100% of the time..just like spark is controlled by MAF (when enabled).

In no case does it dictate that your VE Table does not need to be accurate, but I think the PCM may act differently in airmass and fueling computation when MAF is enabled, vs MAF failure.

It almost is like when MAF is enabled it is close to 100% determining airflow. Again, I can not prove it..just am amazed that a +/- 15% VE Airflow change would have almost a negligible effect on Trims.

We need a PID that tells you have much MAF, and how much VE Table is being used... (I know you have a PID that comes close!)...

[5.7ute]

What I mean by B4107??? is I cant find that table. Is it a typo?

[WeathermanShawn]

B4107:

Mick, on my OP..2002 Camaro-Z28..It is the Table that determines what Closed-Loop-Mode you are in.

Interestedly, it is referenced by SAE.MAF (g/s)..I know if you go SDCL it is DYNAIR.DMA, but the Table for MAF users..does say SAE.MAF.

Just makes you wonder? I know you can do loop-up Tables to reference what Closed-Loop Mode you are in, but it might explain how Trims are applied when MAF enabled..I..E..B4106 LTFT Update Filter.

Sorry, I know every OP is different..but may be an important distinction.

[mr.prick]

I used GM.DYNCYLAIR_DMA as it is in g/cyl and {B4107} used to be linked like this:

;Closed Loop Mode
B4107.ROW=GM.DYNCYLAIR_DMA,GM.CYLAIR_DMA,GM.DYNCYLAIR,CALC.CYLAIR 

Check out this thread:
{B4105} how do i link this table?