Granatelli MAF issues

jwalker · January 8, 2006

Hello.

I've serched this whole site regarding the Granatelli MAF & haven't found the answer I'm looking for. I put on the new MAF yesterday & have had nothing but problems. If seen others on this forums with simular problems but no info on how to rectify them.

I installed a K&N cold air intake, Gibson exhaust, & the Granatelli MAF yesterday afternoon. After reconnecting the battery, I turned the key on & off 3 times to let the computer cycle properly. I then started the truck & took it for a test drive, stop & go traffic, even shut it off 3 times. No problems.

I then went back to the shop & cleaned up my mess & headed for home, about 70 miles.

On the way, my check engine light came on. I stopped at the local Autozone & had them hook up the computer. Sure enough, a Mass Air Flow sensor, low voltage code was logged. So I went home, disconnected the battery for 1 minute & reconnected, hoping this would reset things & fix the issue. I then started the truck, only to have it die & wouldn't restart.

So I decided to reconnect the stock MAF. After the re-install of the stocker, the truck started right up. Ran smooth as before this journey started.

My couriosity got the best of me, so I removed the stocker & put the Grantelli MAF back in, just to see what would happened. After the re-install, I started the truck & it died immediatly. This happened 2 times. On the 3rd try, it started but chugged like a tractor. I shut the truck off, waited 1 minute, & restarted. It started but again ran rough for 30 seconds, then the idle smoothed out & it ran just fine.

So I started & restarted 3 more times, no problems, drove into my parking spot & called it a day, thinking I outsmarted the d**n thing.

This morning I get into the truck to go back to the Autozone to have the check engine light reset. Truck starts right up, runs great, I head of to the store.

The guy at Autozone resets the computer, I thank him, he leaves. I hit the key to start the truck & it stalls. 2 more times, 2 more stalls. On the 3rd time, it starts. I drive home, no lights, no problems, shut it off go inside. Roughly 1 hour later, I start the truck & my old friend the check engine light is on again, but the truck continues to run great with no problems.

I have a call in to GMS, hopefully I'll have the info tomorrow. Has anyone that had problems with the GMS MAF experienced this at all & if so, how did you fix it? If the d**n thing isn't going to work I woud assume it would work at all, not just when it feels the need to piss me off.

Any info would be great.

Thanks.

redvett · January 8, 2006

If your truck is stock displacement take it off and get a refund. The stock on flows more than the engine will require. The 04 MAFS is big enough to support 6.0L and more. Get a tune for better performance.

asilverblazer · January 9, 2006

Oil from the new K&N might have soiled it try cleaning it first. Lots have issues with overoiling the air filter and the oil gets sucked onto the sensor causing issues. Sense it worked welll right at first then quit suggests that it got dirty after a little use.

facn8me · January 9, 2006

Most all the opinions I have seen on the GMS is they are more trouble than they are worth. Get a refund cause it's not gonna gain you anything but down time.

TonyMazz · January 9, 2006

Granitelli MAF is more trouble than it's worth. Get a refund

The K&N filter will introduce more air AND dirt. More flow equals more dirt...take a sample of your oil and send to blackstone...you will be surprised at what is in there ....the K&N introduces more horsepower...bunk..introduces more air, hence more fuel to keep the ratio at 14:1 hence worse economy to increase the potential of more horsepower.

Exhaust may not be a bad idea to get the gasses out...but keep in mind that your truck was designed and tested extensively...and by you experimenting all you are doing as changing the delicate balance that has been tested and true.

...all at the expense of your wallet , your time, and your hassle....

I'd leave the truck operations stock for the best comprise of economy and power....but that's just me....

jwalker · January 9, 2006

After talking to the tech guys at Granatelli & the info on this forum, I've decided to return the MAF. I've already noticed a better throttle response with the original MAF in place. After replacing the stock air intake, I can see why you get better fuel milage & power with the K&N system.

Thanks everyone who responded to my question.

redvett · January 9, 2006

Un-hooking the battery on an OBD-2 vehicle will do nothing you must have it cleared.

hcvone · January 11, 2006

We have tested 6 GMS MAF's on the dyno on 3 different C5 Corvette's, we have never seen any power increases, the stock MAF's always worked better.

vhato · January 14, 2006

The MAF by design is there to tell the computer the volume of air flowing through it. The Computer in your truck is calibrated by GM to be within 10% of the actual flow. The Granatelli MAF is built with this knowledge and plans to correct the factory programming into a 2% correction by misrepresenting the acutal flow values (Low/High voltages). Power and economy wise, this *CAN* be a substantial gain. Custom programmers like Nelson, Westers, etc, calibrate the PCM to be within 5% of the stock MAF which is why so many people report improved part throttle driving and much faster throttle response.

The problem with Granatelli's thinking is vehicles are sold in different parts of the country, with different air pressures. Not every engine is exactly the same, and people mod their vehicles with new Intakes, Exhaust, Filters, Programming, etc. All of these issues are at the extreme end of GM's 10% Calibration for the MAF. Granatelli MAF's assumption it is forcing a 2% Calibration may make your engine run too lean or too rich, especially if the truck has any mods to it.

If you have diagnostic software you can watch what are called Long Term Fuel Trims to see how wacky things get. The computer will be constantly fighting BOTH extreme rich and extreme lean conditions (one after the other), resulting in poor idle, poor acceleration and poor fuel economy.

Granatelli had the right idea, but next to impossible to solve without custom programming.

Hope this is the explanation you were looking for.

VortecMax · January 14, 2006

After talking to the tech guys at Granatelli & the info on this forum, I've decided to return the MAF. I've already noticed a better throttle response with the original MAF in place. After replacing the stock air intake, I can see why you get better fuel milage & power with the K&N system.

Thanks everyone who responded to my question.

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I also installed a Granitelli MAF sensor and it seemed to work but with very little increase in any performance. I returned it and exchanged for a Hypertec programer, thats a much better investment in performance.