Compatibility Issue with Granetelli MAF and Diablo Predator
Compatibility Issue with Granetelli MAF and Diablo Predator 
Is anyone having an issue with a lean condition when running a Granetelli MAF while having a Diablo Tune on an LS1 car? I recently put both on and ever since I started getting two heater malfunction codes and two lean condition codes. Between the Diablo and the MAF those are the only two things I've done to the car that would create a lean condtion....so if anyone has any ideas, I'm open for suggestion at this point.... 
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From: sofla
The Predator leans out the PCM properly by altering fuel trims in the PCM.
The MAF is tricking the PCM into thinking there is less airflow than ther actually is, thus the PCM delivers less fuel.
For best results, I would suggest replacing the MAF with the stock unit, as they tend to be more accurate and consistent, and will produce a proper A/F ratio with the Predator tune.
The MAF is tricking the PCM into thinking there is less airflow than ther actually is, thus the PCM delivers less fuel.
For best results, I would suggest replacing the MAF with the stock unit, as they tend to be more accurate and consistent, and will produce a proper A/F ratio with the Predator tune.
It isn't abnormal for a Granetelli to throw lean codes. Put the stocker back on or use the predator to adjust the Part Throttle fueling (add about 6%)
When you say heater codes, are you refering to the O2 sensors? If so, O2 heater codes are often caused by Long Tube headers. Did you recently install a set?
When you say heater codes, are you refering to the O2 sensors? If so, O2 heater codes are often caused by Long Tube headers. Did you recently install a set?
Personally, I never had a problem with my Granatielli MAF. They had done their 'cold air kit' calibration on mine since I had a lid. When I dyno'd my '99, it made some pretty decent numbers with a stock tune. I had a feeling the handheld I had at the time was leaning it out too much. So, I kept the MAF over the handheld. Since your handheld has a little more functionality than mine did, you could hook up to a WBO2 and adjust your WOT AFR in the PE table.
Most likely, your code problem is due to your long tubes. Yes, the combination of a handheld and a Granatelli MAF will lean out the engine. However, it won't be so lean that it throws a code. There's something else going on...
Most likely, your code problem is due to your long tubes. Yes, the combination of a handheld and a Granatelli MAF will lean out the engine. However, it won't be so lean that it throws a code. There's something else going on...
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You are using two sets of magic beans. Both Granatelli and Diablo both know that on a stock Fbody calibration the fueling is pretty fat. The MAF beans add a resistor to demand more current thus fooling the MAF into demanding less fuel with the stock MAF calibration. The Diablo leans out the PE table and adds some spark. Both sets of Magic Beans together is too much. The Heater code is from the O2's not heating up fast enough-most likely due to the new further down placement in your LT's. I would say keep the MAF but, carefully remove the added resistor from it. Ditch the Diablo, and get a real tune. OR if you have to keep the Diablo, because of lack of qualified shops/tuners in the immediate area or limit of funds, once again either swap the MAF for a stocker as mentioned before, or remove the resistor.
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