I have a 03 Silverado SS with a Radix SC, I was looking thru my tune and it seems like I missed this originally, Here is a copy of my question from SilveradoSS.com:

I'm using HPtuners for my tuning needs...I was looking thru my tune tonight and came across Cylinder Charge temperature. It is under the General Airflow tab.


"Dynamic Airflow - Use Charge Temperature Model: When enabled, the VCM will use a complex charge temperature model to calculate manifold air temperature. The calculation is an airflow bias between IAT and ECT. When disabled the VCM will use just the IAT. It is useful to set this to disabled for forced induction applications where the IAT sensor is relocated."


That is the description listed on the bottom of the screen...Since I have a radix I'm gonna disable it. My IAT sensor is relocated to the manifold already, so it looks like this is what I need to do. A question I have is what all will this affect? Airflow calculations resulting in my MAF being off? Timing being pulled due to high IAT's ? If you have done this let me know how it worked out, if you haven't maybe you should look at it. I'm gonna copy this to the HPtuners board as well. I am still on the learning curve so bear with me if this is a dumb question.

Could this be throwing my comanded AFR off as well? Thanks again.

Dave

 

I have mine enabled. Dewey has his disabled. I'd leave it on. It will use both ECT and IAT to get the airmass value. You may also what to change the bias values to 1.0 so it uses both the ECT and IAT equally.

 

Older model PCM's have it disabled from the factory. You will probably have to rescale the VE table and it will throw off your trims slightly if in SD.
Before you copy paste on HPT do a search there is a good thread about 10 pages long with what different guys have done it all stems from the leaning issues with high IAT's. My bias is currently around .95 I like it crutched to the IAT side. If I remember right 0=total air mass calc off of IAT and 2=total air mass calc off of ECT with 1 being an even mix.

 

The thing is, as I understand it, since from the factory the IAT sensor is in the MAF the computer takes the IAT value and converts it to a Manifold Air Temperature (MAT) value. My IAT sensor is in the intake after the blower(radix). When you take into account the heat sink from the aluminum intake and the fact that it is measuring boosted air. I see no reason to leave dynamic airflow enabled. Thanks for the advice...I'll check HPtuners. Later

Dave

 

Tattle Tail!


I have come to this same conclusion, okay maybe a little different conclusion-not to sure about the MAT thing and if boosted air has much to do with it. I tried to make it work. I hate the lean start up issue. But that CCT really F's with the ve table. You have to rescale and rescale. Yuck! Wilde racing has his IAT right at the front of the TB and I am guessing 02sierraz71_5.3 (btw your screenname pisses me off when I try to copy it by double clicking it It only highlights part of due to the underscore, I guess my 3rd scotch for the night makes it aggrevating a little more than normal LOL) has his in the MAF. I've never read about him relocating his. WIth that said, a relocated maf to the manifold makes this a different beast IMO. The IAT temps can move a little quicker and mean a little more rather than a non-relocated one. Mine is off. And it'll stay off until I am 100% happy with my tune and I have nothing else to do for a month. Then I'll THINK about tackling it (or attempt to).

 

Who me? lol
Dewmanshu makes a very good point, where your IAT is located plays a HUGE part in what the bias should be imo.

 

good point, mine is still in the MAF and you guys know the closer it is to the intake valve the more accurate the reading. If youve relocated the IAT I personnaly dont think CCM is needed the only reasoning I can see behind it is to cover up for GM being cheap not putting the sensor close to the head runner and also using something thats cheap and gets heatsoaked.

When I build a new engine you know its gonna be behind the throttle body or closer to valve if I can figure something out.

 

My IAT sensor is within 6 inches of the intake port. Also the big thing is that boosted air is hot air, the shear act of "squeezing" the air heats it up. Once the hot air passes thru the heat exchanger it is then measured by the IAT sensor. If my sensor was in the MAF it would be way off. In essence my IAT sensor is a MAT sensor (manifold air temp) and I don't need the multipliers of the cylinder charge temp. Maybe I answered my own question? Later

Dave

 

True dat! Settled then! btw, what's that SS running in the 1/4?

 

You most likelly seen this pic, but This is were mine is.