navy-et

I know that the auto trans in the c6 cars are dependent on the ls3/7 card style maf to shift properly. My question is can I switch to the older truck maf and just rescale the table for the different diameter? What am I looking at to get this done. I'm having major issues with air turbulence from the split intercoolers. I'm dropping about 1000hz at idle. I have hp tuners with the new beta

Thanks guys

TurboLX

Is this with an APS kit? I made a 3.5" MAF housing for my LS3 and welded a MAF saddle for the stock LS3 (hitachi) element onto it at the 3 o'clock position. I trimmed the silicone "Y" about 1.5" and had a short section of straight pipe before my MAF element.

The trick is to make sure you have minimal noise on the MAF Hz. Changing to the older Delphi style element will not likely make this better. The LS3/7 MAF element is pretty much the best one on the market for stability and resistance to reversion at idle. Just make sure you position it so that it isn't subject to turbulence. Fix the mechanical issue first...

Either way, the MAF transfer function has to be pretty much right on reality for everything (fuel, spark, trans) to work as intended. Any errors in airflow measurement at the MAF will skew the calculated engine torque estimate, which in turn can screw up transmission controls. Fixing it requires that dial in the MAF curve specific to your car. I highly doubt that you will get "drop in" data for whatever MAF in whatever pipe, with whatever bends you happen to have on your car from another source that wouldn't need modification to be exact on your car.

navy-et

Ha ya its APS, the split intercoolers are causing a lot of turbulence, I have a 4" tsp maf housing right now and I think all the transitions in size are causing air turbulence, I screened the maf and it still dropping between 400hz and 1000hz at idle, even with the idle set to 800rpm. Did you use a silicone y or did you fab up a hard pipe all the way from intercoolers to the TB ? I think a lot of my issues are from that ****** y coupler that comes with the APS kit

TurboLX

The silicone Y from the kit isn't causing the turbulence, the transition up to that 4" MAF tube is. Been there, done that. Put the MAF element in a 3.5" tube (which is the same diameter as the outlet of the "Y") and you'll see the MAF signal all of a sudden get much more stable! I use the silicon "Y" on my car, but I cut about two inches off the outlet side of it to fir my straight 3.5" MAF tube (which is about 6" long) before the hump connection to the throttle body. I have a VERY stable MAF signal now.

edge04

out of curiosity why not just eliminate the maf?

navy-et

I would love to but the car is an auto trans, all the programming for the trans is directly related to the maf signals, if I went speed density is blow the trans within a week.

navy-et

Ok thanks turbo lx , I'll do that and hopefully my tuning gremlins will go away, I'd love to drive this car normally haha

tblu92

If your MAF HZ reading is low as you say like 1000HZ this is a common problem with altered MAF placement or altered intake tube diameters---
Even on my C7 with a new AFE CAI I experienced the same issue--Stock I would have a MAF reading of 2400 HZ---But after the AFE install the idle HZ went to a lower 1800 HZ
A simple MAF re-scaling will fix it---With the stock airbox at 2400 idle HZ the MAF showed like 10.60 lbs----So what I did was to rescale the MAF table so it would show 10.60 lbs at 1800 HZ---It was about a + 21% to the entire MAF table---
Same results at WOT as well--Stock airbox I would hit approx. 9400 HZ---but with the AFE intake only 8850 HZ--- Stock would show 430 Lbs at 9400HZ adding that 21% now made the MAF read 430 lbs at 8850 HZ
Altered MAF signals for whatever reason causes your engine to show less load---But by rescaling the table will make the load value closer to the stock value--My car is an auto as well---and I have experienced no problems after the resacling---Same theory goes for most any LS engine as well--
PS: on the C7's now Diablo has a special tune exclusively for a C7 with an AFE CAI--now verifying the need for a major MAF rescale

TurboLX

First, fix the mechanical concern (turbulent flow at the element), then you can proceed to calibrating the curve properly.

Here's my MAF setup on the APS kit with an LS3 slot element...



Notice how the entry into the MAF measurement section of the pipe is smooth and does not change in cross sectional area very much near the sensor? THAT is very important if you want a consistent signal.

tblu92

I DO AGREE-----You need to make the transitions in the intake tube as turbulent free as possible 1st---
The older style MAF's ( pre slot style ) that were a complete unit were a little more forgiving as to intake turbulence---Some of them had a honeycomb type screen on the intake side of the MAF unit---HOWEVER this is NOT a screen---It is a "stream straightener" placed there to combat turbulence before the air entered the MAF wires-- giving it a far more accurate reading in aftermarket intake systems