MAF curves with larger injectors

QWKSNKE · 05-12-2005, 02:41 PM

Can I run 60's in my car with the 42# Maf and tune the curve with the tweecer or will I have to change MAF's to?

Italian LX · 05-12-2005, 02:47 PM

In theory, you could do it, but only up to a certain flow-rate. You would likely end up pegging the MAF if you tried it that way. However, you can go the other way though.

Sendero · 05-12-2005, 03:14 PM

Aren't there guys running 55lb injectors with Lightning MAF's? I was under the impression that the MAF curve was just a measurement of incoming "metered" air and that the injector slopes were responsible for sizing the pulsewidth.

The only reason you had a MAF "calibrated" for X size injector was due to many people not having access to tuners with the ability to change fuel parameters? That way when a Mass Air Meter was calibrated for 42lbs could be installed on a car with 24lb injectors originally. Like the C&L meters with different sized flow tubes. Its the same meter, you just change out the flow tube to trick the ECU into thinking its flowing less air so you'll get less fuel from the bigger injectors.

It makes sense, but I could be wrong...

Italian LX · 05-12-2005, 03:51 PM

Quote:

Originally Posted by Sendero

Like the C&L meters with different sized flow tubes. Its the same meter, you just change out the flow tube to trick the ECU into thinking its flowing less air so you'll get less fuel from the bigger injectors.

There is a difference between tricking the computer mechanically and tricking it electronically.

The reason the C&L tubes work is because the different size tube allows the MAF element to cool less at the same flow-rate and, therefore, give off a lower voltage at that same flow-rate. (Keep in mind that this only works if your computer still thinks you are running the stock injector size.)

As far as tricking the computer electronically, you would have to give it the wrong injector slopes in order to use a MAF for smaller injectors. However, this only works up to the point that the meter peggs out. You must remember that when you increase injector size, it has to be because you are increasing your airflow; if you change nothing in the MAF, then you will reach 5v very quickly.

Perfect example is my car. I am running 24# injectors. If I attempt to put my stock MAF back on, there is absolutely no amount of programming I can do to keep me from pegging 5v before it even gets anywhere near my current shift point.

Think about this and then tell me if it makes sense.

.

Wicked · 05-12-2005, 04:10 PM

Factory MAFs are all open curves, meaning they output based on airflow. The injector tuning is all in the ECU programming.

Aftermarket MAF's are tuned to be setup for specific size injectors to trick the computer to believe the stock 24's(or whatever is stock in your vehicle) are still in place.

If you have a 42# calibrated MAF and go to 60# injectors you could tune it in just like every other tuner does. You are not changing your airflow so it will not be a problem for the MAF(pegging).

Its the same as a MAFExtender, multiply your hi and lo fuel slopes, and displacement by the 60/42 factor to shorten the injectors pulses.

Wicked · 05-12-2005, 04:13 PM

Quote:

Originally Posted by Italian LX

However, this only works up to the point that the meter peggs out. .

If he's only changing injectors, not the MAF, he will not peg the MAF if it wasn't pegging before.

Italian LX · 05-12-2005, 04:32 PM

Quote:

Originally Posted by Wicked

If he's only changing injectors, not the MAF, he will not peg the MAF if it wasn't pegging before.

You right in that aspect, but he would be limiting any chance of using the 60# injectors to their potential. If he dicded to pulley up the blower, his injectors may be capable, but he will likely hit the max of the MAF.

Wicked · 05-12-2005, 04:39 PM

Quote:

Originally Posted by Italian LX

You right in that aspect, but he would be limiting any chance of using the 60# injectors to their potential. If he dicded to pulley up the blower, his injectors may be capable, but he will likely hit the max of the MAF.

I totally agree.

Sendero · 05-12-2005, 04:51 PM

Quote:

Originally Posted by Italian LX

You right in that aspect, but he would be limiting any chance of using the 60# injectors to their potential. If he dicded to pulley up the blower, his injectors may be capable, but he will likely hit the max of the MAF.

Are we talking about just changing the injector slopes and not the MAF curve itself?

QWKSNKE · 05-12-2005, 04:55 PM

Any difference if I use a 55# MAF

05-12-2005, 02:41 PM	#1
QWKSNKE 3v's are slow Join Date: Dec 2004 Location: Here and There Posts: 17,152	MAF curves with larger injectors Can I run 60's in my car with the 42# Maf and tune the curve with the tweecer or will I have to change MAF's to? __________________ 2009 Porsche Carrera S 2008 ///AMG C63.. Eurocharge Tune. RIP 2019 AMG GLC43..wife's 03 F250 SD.. Edge Evo, AFE Stage 1 CAI 08 GT. JBA axle back, FRPP springs, FRPP swaybars.. daughter's 01 Cobra vert... wife's I need a new toy

05-12-2005, 02:47 PM	#2
Italian LX Daddy x4 ...we're done Join Date: Dec 2004 Location: Oxford, AL Posts: 11,551	Re: MAF curves with larger injectors In theory, you could do it, but only up to a certain flow-rate. You would likely end up pegging the MAF if you tried it that way. However, you can go the other way though. __________________ -Brian '86 Mustang GT Convertible '88 Mustang LX coupe '11 Odyssey TE '21 Insight Touring

05-12-2005, 03:14 PM	#3
Sendero Im gonna show her my... Join Date: Dec 2004 Location: Somewhere providing FREE tech support. Posts: 4,269	Re: MAF curves with larger injectors Aren't there guys running 55lb injectors with Lightning MAF's? I was under the impression that the MAF curve was just a measurement of incoming "metered" air and that the injector slopes were responsible for sizing the pulsewidth. The only reason you had a MAF "calibrated" for X size injector was due to many people not having access to tuners with the ability to change fuel parameters? That way when a Mass Air Meter was calibrated for 42lbs could be installed on a car with 24lb injectors originally. Like the C&L meters with different sized flow tubes. Its the same meter, you just change out the flow tube to trick the ECU into thinking its flowing less air so you'll get less fuel from the bigger injectors. It makes sense, but I could be wrong... __________________ I heard it on the internet, so it must be true. "I believe that a person's moral compass can be determined by how he references free men the right to defend themselves." T. Nugent "An armed society is a polite society. Manners are good when one may have to back up his acts with his life." R. Heinlein "Never argue with an idiot. They drag you down to their level, then beat you with experience." -Unknown

05-12-2005, 04:10 PM	#5
Wicked Friends Join Date: Dec 2004 Location: Pell City, AL Posts: 1,371	Re: MAF curves with larger injectors Factory MAFs are all open curves, meaning they output based on airflow. The injector tuning is all in the ECU programming. Aftermarket MAF's are tuned to be setup for specific size injectors to trick the computer to believe the stock 24's(or whatever is stock in your vehicle) are still in place. If you have a 42# calibrated MAF and go to 60# injectors you could tune it in just like every other tuner does. You are not changing your airflow so it will not be a problem for the MAF(pegging). Its the same as a MAFExtender, multiply your hi and lo fuel slopes, and displacement by the 60/42 factor to shorten the injectors pulses. __________________ 2001 Cobra 'Vert Procharged and Intercooled 455rwhp/441rwtq Work Car: 2005 Honda Odyssey 400 whp Turbo V6, 6-speed, full cage, H&R Suspension, Brembo Brakes

05-12-2005, 04:55 PM	#10
QWKSNKE 3v's are slow Join Date: Dec 2004 Location: Here and There Posts: 17,152	Re: MAF curves with larger injectors Any difference if I use a 55# MAF __________________ 2009 Porsche Carrera S 2008 ///AMG C63.. Eurocharge Tune. RIP 2019 AMG GLC43..wife's 03 F250 SD.. Edge Evo, AFE Stage 1 CAI 08 GT. JBA axle back, FRPP springs, FRPP swaybars.. daughter's 01 Cobra vert... wife's I need a new toy