Maf question
Thread Starter
Melting Slicks
Joined: Nov 2003
Posts: 3,011
Likes: 9
From: Dublin GA
Maf question
Well; Due to the feedback I got here and another thread, I swapped out my "heavily ported" MAF for a stock, descreened one. Now; I haven't had any issues with the ported one, but because of feedback that the stock ones would be better for part throttle, I swapped back.
The car was dyno turned with the ported MAF, once after new heads, and again after my cam and a few more mods. The problem is, since I have swapped back, the car just won't idle. It "hunts" from 600 to 1500 rpm, and shuts off when I put it in gear. I have probably only put 50 miles on it since I swapped, and was getting no better. Since I'm leaving tonight (Friday) going to the Mountains (In the car
) I swapped back, and now it idles PERFECT
)
Question; Is this because the tuner somehow matched the new airflow during the tune? I have HPTuners (Still learning) but there is no time to make adjustments before I leave, so when I return, what should I do?
The car was dyno turned with the ported MAF, once after new heads, and again after my cam and a few more mods. The problem is, since I have swapped back, the car just won't idle. It "hunts" from 600 to 1500 rpm, and shuts off when I put it in gear. I have probably only put 50 miles on it since I swapped, and was getting no better. Since I'm leaving tonight (Friday) going to the Mountains (In the car
) I swapped back, and now it idles PERFECT)Question; Is this because the tuner somehow matched the new airflow during the tune? I have HPTuners (Still learning) but there is no time to make adjustments before I leave, so when I return, what should I do?
Tech Contributor
Joined: Apr 2007
Posts: 10,924
Likes: 78
From: Forney Texas
Yes. The measured airflow and resulting output frequency is affected by the removal of the screens and porting. It's not necessarily flowing more air, but the calibration has been compromised with the MAF modifications. It would require tuning with the other MAF for it to work. Anytime you swap out your MAF, you're going to have this issue I'm sure. It will be this way unless you swap stock for stock in a PCM tuned for stock.
Team Owner
Joined: May 2001
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From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
Yes. The measured airflow and resulting output frequency is affected by the removal of the screens and porting. It's not necessarily flowing more air, but the calibration has been compromised with the MAF modifications. It would require tuning with the other MAF for it to work. Anytime you swap out your MAF, you're going to have this issue I'm sure. It will be this way unless you swap stock for stock in a PCM tuned for stock.
If the tuner did a speed-density tune, even that "little" of a change can have noticeable effects.
Team Owner
Joined: May 2001
Posts: 36,836
Likes: 244
From: Dear Karma, I have a list of people you missed.
St. Jude Donor '08-'09-'10-'11-'12-'13-'14-'15-'16
Melting Slicks
Joined: Aug 2006
Posts: 2,167
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From: Powell TN
Cruise-In VIII Veteran
Usually because in the '01 and up, the IAT was part of the MAF. It's easier to leave it in than rewire for the intake air temp.
You tune the VE for any/all tunes. He is referring to a speed density tune. Speed density means that you don't use readings from the MAF, so if you don't need it to hold your intake piping together, and it doesn't have the IAT integrated into it, then it is just a restriction, so yea, you can just toss it.
You tune the VE for any/all tunes. He is referring to a speed density tune. Speed density means that you don't use readings from the MAF, so if you don't need it to hold your intake piping together, and it doesn't have the IAT integrated into it, then it is just a restriction, so yea, you can just toss it.
Drifting
Joined: Mar 2005
Posts: 1,737
Likes: 0
From: Northern VA
You tune the VE for any/all tunes. He is referring to a speed density tune. Speed density means that you don't use readings from the MAF, so if you don't need it to hold your intake piping together, and it doesn't have the IAT integrated into it, then it is just a restriction, so yea, you can just toss it.
Just because you tune in speed density mode (i.e. MAP), doesn't mean you run in speed density mode.
A MAF tune should be a LOT cheaper than a properly done speed density tune since it takes much more time.
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Melting Slicks
Joined: Aug 2006
Posts: 2,167
Likes: 11
From: Powell TN
Cruise-In VIII Veteran
Actually, MOST tunes are MAF tunes. The VE isn't touched. Speed density tunes aren't required for headers, or a vararam...or a Centri on a stock engine.
Just because you tune in speed density mode (i.e. MAP), doesn't mean you run in speed density mode.
A MAF tune should be a LOT cheaper than a properly done speed density tune since it takes much more time.
Just because you tune in speed density mode (i.e. MAP), doesn't mean you run in speed density mode.
A MAF tune should be a LOT cheaper than a properly done speed density tune since it takes much more time.