02 Z06 airflow tuning

[ChucksZ06]

Car has 250 on a 111 lca cam with fast 90 and ls2 ETB. The GM.CYLAIR_DMA is about one half ( .21 g) to GM.DYNCYLAI...speed density ( .43 g) . When I log stock cammed vehicles these two pids stay mostly the same. I have not been able to figure out what tables affect these two pids. Is the first one actual grams and the 2nd one calculated? Also engine idles at 70 kpa MAP and MAP drops to 50 or lower at say...a steady state throttle at 2000 rpms. Is this normal with a larger cam? It seems as though the ETC throttle position does not jive with the indicated?
Car runs well at higher rpms(3000 and up). It pulls hard. I am running open loop with the maf working. It idles ok at 900 but I am thinking my transition is hurting because I am not matching up the previously mentioned pids.
I have not been able to find a vacuum leak. Any suggestions would be appreciated. Thanks. Chuck

[TFZ_Z06]

Car has 250 on a 111 lca cam with fast 90 and ls2 ETB. The GM.CYLAIR_DMA is about one half ( .21 g) to GM.DYNCYLAI...speed density ( .43 g) . When I log stock cammed vehicles these two pids stay mostly the same. I have not been able to figure out what tables affect these two pids. Is the first one actual grams and the 2nd one calculated? Also engine idles at 70 kpa MAP and MAP drops to 50 or lower at say...a steady state throttle at 2000 rpms. Is this normal with a larger cam? It seems as though the ETC throttle position does not jive with the indicated?
Car runs well at higher rpms(3000 and up). It pulls hard. I am running open loop with the maf working. It idles ok at 900 but I am thinking my transition is hurting because I am not matching up the previously mentioned pids.
I have not been able to find a vacuum leak. Any suggestions would be appreciated. Thanks. Chuck

The engine in my sig is about 60kpa (112LSA) at idle and the CYLAIR and DYNCYLAIR are almost the same according to my last log. 70kpa is about what I would expect from your cam, lots of overlap and duration = vacuum loss. I would try looking at the VE table for adjustments.

[Highlander]

Chuck you have a problem in your tune... I didn't know you had a fast and an ls2 TB... I may be able to help you out a bit further but keep things in one thread...

did you try the file I sent you? What does your RAFIG look like?

[Highlander]

Nevermind, that thread was from someone else....

I can help you out with a tune if you email me your tune or post it here...

[ChucksZ06]

Thank you and I apologize for different threads...different problems that were at different times. I have to figure out how post the tune... I appreciate the offer to help. I cannot read your tune with my V7.3 software. I will get upgraded soon.

[Highlander]

your tune is different...

email it to dyno@autoxdyno.com and i'll email you back a "fix" or a partial file that might help.

[WeathermanShawn]

I always found this thread helpful.

It was posted by 'Joecar" at one point. May also be in one of the stickies.

..Quote
SAE.MAF - C.A.R.B. Mandated PID that returns airflow in grams per second. GM (and all manufacturers) are required by law to provide this PID. Also, C.A.R.B. mandated a scaling that is different from the GM.MAF version of this PID. Therefor you will see slightly different values due to different processing required to format each value.

GM.MAF - see above.

GM.DYNAIR - GM's estimated airflow in grams per second based on the VE table. This value is calculated independantly of the MAF. It is used to test MAF rationality and when the PCM is in speed density mode (i.e. MAF removed or disabled).

CALC.CYLAIR - EFILive's calculated grams/cylinder value. It is calculated as {SAE.MAF.gps}*15/{SAE.RPM}

GM.DYNCYLAIR - GM's estimated airflow in grams per cylinder based on the GM.DYNAIR value.

GM.CYLAIR_DMA - internal (DMA) PID that is used by the PCM as an index to look up various tables that are indexed on grams/second. This values is derived from the MAF signal.

GM.DYNCYLAIR_DMA - internal (DMA) PID that is used by the PCM as an index to look up various tables that are indexed on grams/second. This values is derived from the MAP, RPM, IAT and VE tables and is independant of the MAF.

We added the last two (DMA) PIDs because they give more accurate feedback of the indexes (indicies?) used by the PCM when looking up table values. We found that the non-DMA PIDs sometimes lagged actual operating conditions by a frame or two...Quote..

GM.CYLAIR.DMA is derived from the MAF signal. The GM.DYNCYLAIR.DMA is basically the value computed from your VE Table. Either your MAF is under-reporting true airflow, or your VE Table is over-reporting true airflow. If your airflow is that far off, your fueling must likewise be way off.

[Kurtomac]

question....i swapped a new cam in my z06 not too long ago....just yesterday i decided to log sae.maf....it was showing about 9grams at idle....my desired air was way higher than that...when i checked running airflow derived from the VE table gm.dynair on average it was about 3 g/s higher than SAE.MAF...made a change to my desired table and im gonna go out for a startup log here in a min...yesterdays tune had a whole lot of changes....so im gonna give this a try and see where i end up...curious as why the maf is saying 9 g/s and the other is 12g/s?

[WeathermanShawn]

The SAE.MAF data is simply a look up table based on what is inputed on Table B5001 (MAF Calibration). Change those numbers and you will change the value you see on GM.CYLAIR.DMA. The pid GM.DYNCLAIR.DMA is also a lookup table based on what the user has inputed on the VE Table and is then calculated using MAP, RPM, IAT, etc.

What you input in B5001 and B0101 has control over how those values are calculated. A lot of what you see logging is controlled by what you type into that column.

Using PID CALC.VE (uses MAF.SAE, charge temperature, and engine size), I recreated a VE Table using MAF flow exclusively. Other than a few cells in idle, it gave a VE Table that was as close to the AUTOVE SD tunes I have. GM.CYLAIR.DMA and GM.DYNCLAIR.DMA now reflect identical values.

[ChucksZ06]

Thanks weatherman that is some helpful info. I am in process of getting the calc'd airflows to match with the Maf flows. The car will only hook up in 3rd gear so the power is awsome. I disabled the LTFTs and that made a big improvement in the idle and transition throttle. I appreciate the help from you guys. Chuck