Granatelli MAF question

[AaronGTR]

I have been dealing with these POS MAF sensors for years with the f-body's. I am quite sure they are exactly the same as these units. In simple terms, They send a lean reading to the PCM so in turn the PCM will richen the A/F ratio. (Adding more fuel)


This is due to the false reading the MAF is sending as I stated above

I'm sure you have been dealing with these on F-bodies for a long time... but F-bodies aren't N-bodies now are they. It's apples and oranges. You're talking about one car already with an LT1 or LS1 MAF and another car going from a smaller MAF to a larger LT1 MAF. The way the aftermarket company has to calibrate them so they put out the correct signal is different. If you get a lean or rich signal and whether it's intentional or not is irrelevant. The fact is that you can't get the signal close enough to reporting the actual air flow just by tweaking the guts of the MAF. You need to be able to adjust the values in the pcm.

[prophiseer]

The pcm doesn't react as fast though to O2 readings as it does to MAF readings. You'd be surprised how long it can take between the O2 sensor reading rich or lean before you see the correction in short term fuel trims. And no, you won't see a DTC from that. There are many factors that can cause a rich or lean condition and the pcm doesn't automatically blame the MAF if the O2 sensor reads a lean condition for a certain MAF value. I've seen people have this idle problem time and again with these MAFs. Bottom line is you shouldn't buy one unless you plan on tuning the pcm too.

Oh, I thoroughly understand all that, most of the time you'll see a DTC for 'P0171/P0174 - sys too lean' or some kind of 02 code. And besides, the rearward 02's have to come up to temp before the PCM starts comparing the values front and back. Around this region here, usual suspects of a lean condition rolling into the shop are the MAF or the fuel pump (still gotta verify it, though ). But it's all no major concern at this point, she's en-route back to it's shelf !! My whole initial concern was if anyone else experienced the same problems or not. I thought it kind of odd for the motor to continue with that rough of an idle, surge, and get stupid at WOT without ever kicking the MIL. Just wanted to see if anyone else ever had similar issues (considering customer service at Granatelli told me that was normal <*coughs*> bullshit!, bullshit!).

[ProjectMM]

Sense everyone is saying that there all bad, I've had one in my 02 GT1 for almost 2 years. never had a problem. i got one pretty cheep, so i thought i'd try it out. She runs grate from idle to WOT! sounds like i might have gotten lucky!

[torq455]

I had the same problem when I removed the screen in the stock MAF. After a little cool down it just couldn't find an idle , would end up dying, and had a hell of a time getting it restarted. put the screen back in, it's fine! I figure you can only tune the computer so much. then adding a diff MAF will screw things up. my dad did a tune on his car, then put the Granni in and it ran worse. might have worked if he hadn't tuned the computer...

[IsaacHayes]

projectMM does yours have a screen?

I've heard from teh GTP guys that some guys can remove the screen and be ok, others cant. Just depends I guess on the motor/MAF/ECM and probably more importantly, the turbulance going to the MAF from your air intake tubing...

[ProjectMM]

no it didn't have a screen, strate through, and infront of that I'm running a factory K&N air filter. I clean it every oil change!

[ProjectMM]

no it didn't have a screen, strate through, and infront of that I'm running a factory K&N air filter. I clean it every oil change!

PS. Seems weard to me that taking the screen of made it run worse? I've done it to a lot of different vehicles and didn't afect driveablty at all. I even tested it on a dyno and saw 2hp after removing the screen. but that could have just been the dyno. or maybe the car cooled off a little. but it ran just fine is all i'm saying

[AaronGTR]

Yeah, I think it depends on your intake design and how much turbulence there is going into the MAF. The screen is just there to make sure the air is going straight because a lot of the stock intakes have bends right before or after the MAF and use those rubber flex tubes with all the ribs in them.

[IsaacHayes]

Yup what Aaron said.