Granatelli mass airflow sensor
09-20-2009, 10:03 PM
#5
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On our trucks the computer uses the MAF signal to determine shift points. The aftermarket MAFs are not calibrated the same as the stock MAF. So, for a given volume of air, the aftermarket MAF will underreport that volume, this causes the PCM to increase ignition timing slightly, which is the resulting increase in power and cause different shifting patterns thus ruining a transmission overtime.
When tuning for an aftermarket MAF, the PCM will be recalibrated so that the MAF reports correctly (or close to correctly), thus leaving no real benefit to the aftermarket MAF. Descreening has the same effect as an aftermarket, and has no benefit other than underreporting the incoming air.
When tuning for an aftermarket MAF, the PCM will be recalibrated so that the MAF reports correctly (or close to correctly), thus leaving no real benefit to the aftermarket MAF. Descreening has the same effect as an aftermarket, and has no benefit other than underreporting the incoming air.
09-21-2009, 04:13 PM
#6
Actually, descreening is meant to remove the airflow restriction that the screen causes. The computer measures voltage draw to maintain a wire temp at 212* above ambient. That voltage draw allows the computer to determine incoming air volume. The aftermarkets have two flaws...1, all the different brands use there own formula for temp reporting. It makes it very difficult to tune when you don't know what the MAF is reporting compared to what it should be reporting. Also, some companies "reporting curve" may be more aggressive than others, which can have adverse effects on your tranny. 2, some companies make their own maf from scratch, some use recalibrated GM units. With this, the airflow is unpredictable.
09-23-2009, 03:07 AM
#7
TECH Veteran
The maf doesn't determin shift points. It does however have an effect on shift firmness as well as tcc lockup. Here's the deal with the maf. With a completely stock truck you can get a pretty decent gain out of it by simply bolting it on until you actually drive the truck around. The Granateli maf isn't calibrated as they say since the calibration comes in the tuning, not the unit itself. Anyone who as tuned a vehicle with an aftermarket maf can attest to this. You could do the same thing by descreening your own. The reason for this is the stock calibrations for trucks are very rich and fooling the maf readings for the computer will temporarily lean it out as well as cause the pcm to read a lower dynamic cylinder air number causing it to give more timing by a natural defalut. After driving it around some though the fuel trims will put the truck back to rich again and any gains will be negated. This mod is a big waste of money. The only reason to descreen the stock maf is if you are getting readings of 11,000hz or higher with the screen still in it. You can descreen it and lower the hz reading since the maf readings become unstable at airflow/hz readings of that high a number. Recalibrating the maf and descreening it will help only in situations like this. We've actually tested maf numbers at work. My best example is one we did on a Camaro. The car still had the stock maf (75mm vs. a truck's 85mm) with screen in it and an SLP airlid with K&N filter. This car had a 430" LSx block motor with 235 TFS heads and a decent hydralic roller cam with full street trim exhaust, etc. The engine put down 530RWHP through a badly slipping trans. Either way we were tuning the car in Speed Density and for amusement we ran pulls to test the air intake. With no air intake on it, just the 92mm throttle body feeding the Fast intake we gained 3RWHP over having the full air intake on with a maf still retaining the screen, accordian style intake bellow, and sealed airlid through the air filter. The most gain I've ever seen by descreening a maf (properly calibrated) was 2RWHP on a well modded GTO I was working on/tuning. I'd be willing to sell you a descreened stock maf with a sticker if that's all you are looking for.
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09-25-2009, 05:44 AM
#10
TECH Apprentice
Don't know that descreening is harmful as such (although the screen is supposed to be there to 'stabilize' airflow) but there is nothing to be gained by descreening the MAF.
You want to remove 'restriction'....go OLSD (MAFless).
You want to remove 'restriction'....go OLSD (MAFless).