Simple MAF/DYNAIR pid question.

[joecar]

...
The only method that I know to change the LTFT's in a MAF system is using IFR.
...

S,

You can also change the MAF table itself.

[redhardsupra]

Its that second assumption that is not necessarily correct. The DYNCYLAIR (SD) does not take into account all the temperature modifiers.

Don't know if that is what you are asking, but I ran into that reality lately. Are we talking about the same PID(S)?

All this has been beaten to death 3-4yrs ago:

http://forum.efilive.com/showthread.php?t=9204

http://forum.efilive.com/showthread.php?t=4709

http://forum.efilive.com/showthread.php?t=3017

May the search force be with you

[WeathermanShawn]

Marcin I have read all that.

It is not current. A week ago you told me dynamic and cylinder airflow should match.

You were wrong.

[redhardsupra]

RHS,

I'm using SSpdDmon's method of leaving the MAF cal stock. The only method that I know to change the LTFT's in a MAF system is using IFR. There was a considerable change (10%) from factory IFR as an initial hack. With original trim(6%) and timing changes(another 2%), plus 2% to put the trims in the ~-2% range. I have only done preliminary changes, now the real tuning can take place.

here's how the discussion between me and Jeff went:
Jeff: SD/MAF is too troublesome, i'm going pure MAF
Jeff, 2 days later: well, maybe MAF alone cannot account for every change that occurs in the airflow or fuelflow, so I'll start changing IFR to make up for it!
me: so you're adjusting IFR to make up for the MAP/MANVAC based changes. Why don't you also add RPM based changes to it, and just call it the VE table?

usually it's just easier to work with the system, not against it...

[redhardsupra]

Marcin I have read all that.

It is not current. A week ago you told me dynamic and cylinder airflow should match.

You were wrong.

hmm? have old OS's changed since then?

How am I wrong? If you're measuring the same physical entity two different ways, shouldn't you get the same result?

If you get different results depending on which method of measurement you're using, I'd be willing to bet a good amount of money that it's your measurement methodology that's flawed.

[WeathermanShawn]

hmm? have old OS's changed since then?

How am I wrong? If you're measuring the same physical entity two different ways, shouldn't you get the same result?

If you get different results depending on which method of measurement you're using, I'd be willing to be a good amount of money that it's your measurement methodology that's flawed.

What I am saying is that GM.DYNCYLAIR does not take into account all the temperature biases you always preach. Matching DYNCYLAIR and CYLAIR is not accurate (you said it was).

[redhardsupra]

I have not seen any proof of what you speak of. Link me, please.

[WeathermanShawn]

Marcin quote:

I absolutely agree that no matter what airflow model you're using, the airflows need to be identical. I will go even further with this statement, and say that they need to agree across the full range of airflows.

Marcin 2007 Quote:

what's the difference between DYNAIRTMP_DMA vs CHRGTEMP_DMA?

I'm looking for a PID that would give me aircharge temp, blended accordingly to airflow and B0115 (newer) or B4901 (older)

also, does anyone know how to add *Kelvin to the general selection so I dont have to make extra custom PIDs for it

Originally Posted by redhardsupra
Here's a longer list of PIDs, could someone please enlighten me as to which ones do exactly what, what platforms they occur on, etc... I have an idea about most of them, but i'd like to hear others' take on some of them.

GM.DYNAIRTMP_DMA - I would guess this is the IAT used at a given instant during SD calculations????
GM.CHRGTEMP_DMA - Calculated charge temperature based on IAT, ECT, Charge Temp Blending, and Charge Temp Filter.

GM.DYNCYLAIR - The PCM's predicted airflow values...maybe based on changes observed in short-term histories and observed/filtered changes? In other words, I believe this pid is designed around transitional throttle.
GM.DYNCYLAIR_DMA - The current grams/cyl. value being used in SD fueling calculations. If the MAF is active, GM.CYLAIR_DMA is the pid to use.
CALC.CYLAIR - EFI Live's calculated grams/cyl. based on MAF flow and RPM.

Sounds like you were pretty confused as a 'newbie'.

If you are saying that GM.DYNCYLAIR.DMA is the airflow after these calculations you need to do some logging. Matching DYNCYLAIR and CYLAIR is easy. But that DYNCYLAIR does not calculate the charge temperature and biases. I can provide numerous logs indicating that.

I have had several people verify that.

VE*MAP/charge temperature

273.15+IAT+((ECT-IAT)*factor) where factor is obtained from this calibration.

Its a myth..

[acomp917]

joecar,
Of course the MAF cal could be adjusted. I'm currently subscribing to the SSpdDmon method. After weighing all(that I know) the cause/effect, I think it is the best 90 percentile approach. I hate going for that last 10%, the returns are not good.

I have not calc'd GM.MAF/GM.DYNAIR yet.

RHS,
I would not say that this has been beaten to death. I think due to limited understanding of exact pid specs, most people are measuring what exits the system with a known sensor(WBO2). I'm not saying that doing so is wrong. In light of missing specs, it might be the only method.

ScarabEpic22,
If I did not need EPA cert. and I had to go to that $$$, I would use an Accel(might like to try BS3).

Shawn,
There is very little conclusive data about the inner workings of this PCM. If you include the human variable, you might find yourself to be better off proofing the data yourself.

To All,
I think I have a semi-plugged injector. After I had to change the IFR 10%(might have gone ~2% too far), I began to think... Then I noticed an occasional knock where there should not be one. I just used DVT to shut off injectors and found I do have a weak cylinder. Just another hassle!

S

[WeathermanShawn]

I have done SSpdDmon's IFR method.

It is fast and the easiest method to correct Fuel Trims. You are left with a pretty lousy VE Table though..it might not bite you unless your MAF fails. My wife's Monte Carlo's MAF just failed..so of course it happens.

When you change those IFR settings, all your airflow calculations must be also adjusted. I agree with your general observation. I have correct IFR settings, correct MAF, and to this day no one can perfectly describe how the VE Table is used. Otherwise it could be done simply. And 4 years later we all still argue over it.

Part of is that you can arrive at a differing calculation in the event of MAF failure than a VE/MAF blend.

If you are MAF, closed-loop you can get away with a lot. As long as your transient fueling, cruise, and WOT match..well then your only concern is MAF failure..but in all honesty you don't have to get it perfect.