MAF curves with larger injectors

[QWKSNKE]

Originally Posted by Wicked

Well, if you can get the flow sheet for the new MAF, why couldn't you get the flow sheet for the old one. Shouldn't you already have it since you have previous tuned the car?

That doesn't really make sense.

Not sure if I understand what you are saying.

The flow #'s I had were not right for my car (which is not uncommon) but it put me in the ball park to start.

If I change to 60# injectors my current MAF transfer curve is going to go out the window. It would be easier to send it back to Pro-M, calibrate it for a 60# injectors and start over rather than just throwing injectors in with the current tune. Odds are it would do like it did last time and not crank because so much fuel is getting dumped into the cylinders during startup

[Wicked]

Originally Posted by QWKSNKE

Not sure if I understand what you are saying.

The flow #'s I had were not right for my car (which is not uncommon) but it put me in the ball park to start.

If I change to 60# injectors my current MAF transfer curve is going to go out the window. It would be easier to send it back to Pro-M, calibrate it for a 60# injectors and start over rather than just throwing injectors in with the current tune. Odds are it would do like it did last time and not crank because so much fuel is getting dumped into the cylinders during startup

Okay, so you are saying its not right to begin with.

So if you had the original flow sheet for the MAF you have, you would be okay.

[QWKSNKE]

Originally Posted by Wicked

Okay, so you are saying its not right to begin with.

So if you had the original flow sheet for the MAF you have, you would be okay.

maybe so. maybe not. Just depends. When you have a modified car it kinda a hit or miss thing. Most of the time it will be close

[Wicked]

Originally Posted by QWKSNKE

maybe so. maybe not. Just depends. When you have a modified car it kinda a hit or miss thing. Most of the time it will be close

So then it could also be hit or miss with a new MAF.

[QWKSNKE]

Originally Posted by Wicked

So then it could also be hit or miss with a new MAF.

yep and it probably would be BUT a recal would put it closer

[Italian LX]

I think you are both missing the key point here -- Lee is already pegging his MAF at the top of his pulls so he should get it recalibrated whether he changed injectors or not.

Remember that there are two issues here and two SEPERATE reasons he is swapping injestors AND the meter. He's calibrating the MAF due to the pegging issues and he's swapping injectors because he's hitting 97% duty cycle.

If he was only hitting around 85% duty cyle, all he would have to do it recalibrate the MAF and use the same injectors. On the other hand, if he was hitting the high duty cycle but not pegging his MAF, then he would only have to swap injectors. In the later situation, he would keep his same MAF tranfer function and just change the injector slopes to match his new units.

[QWKSNKE]

Originally Posted by Italian LX

I think you are both missing the key point here -- Lee is already pegging his MAF at the top of his pulls so he should get it recalibrated whether he changed injectors or not.

.

I wasn't thinking about that.

Regardless though, I would recal whether I was pegging the meter out or not

[Wicked]

Originally Posted by Italian LX

I think you are both missing the key point here -- Lee is already pegging his MAF at the top of his pulls so he should get it recalibrated whether he changed injectors or not.

Remember that there are two issues here and two SEPERATE reasons he is swapping injestors AND the meter. He's calibrating the MAF due to the pegging issues and he's swapping injectors because he's hitting 97% duty cycle.

If he was only hitting around 85% duty cyle, all he would have to do it recalibrate the MAF and use the same injectors. On the other hand, if he was hitting the high duty cycle but not pegging his MAF, then he would only have to swap injectors. In the later situation, he would keep his same MAF tranfer function and just change the injector slopes to match his new units.

Okay, I guess I missed where he said he was pegging the MAF. I only saw that he was out of injector.

So if you are pegging a factory meter, that is an open curve, and cannot be pre-calibrated for a specific injector, then your only option would be a bigger/different MAF or larger injector versus being able to recal the MAF.

[Italian LX]

Originally Posted by Wicked

Okay, I guess I missed where he said he was pegging the MAF. I only saw that he was out of injector.

http://forums.qwiksnake.com/showpost...10&postcount=9

[Italian LX]

Originally Posted by Wicked

So if you are pegging a factory meter, that is an open curve, and cannot be pre-calibrated for a specific injector, then your only option would be a bigger/different MAF or larger injector versus being able to recal the MAF.

I can't really agree or disagree with your statement because I'm not sure if I understand what you're saying.

The easiest way to understand MAF meters is to just forget about anything that has to do with calibrating them for a certain size injector. I think when people talk about meters, they make it way more complicated than it really is. The bottom line is that a MAF measures how much air is coming into your engine. At a certain CFM, the meter will return a voltage somewhere between 0-5v and that's all. Once your motor gets to the point that it's taking in more air than the meter measures at 5 volts, that is when you begin pegging the MAF.

I hope this maybe cleared it up a bit.